High tunel-construction

Introduction
High tunnels are becoming increasingly popular for use by small farms who often market
directly to consumers. Although they have proven to be economically advantageous to farmers
who wish to capitalize on high prices obtained either early or late in the growing season,
permanent high tunnel structures do represent a significant capital investment. The cost for a
standard size tunnel, including plastic (two layers) and all the materials required for construction
can range from $1.50-$2.50 per square foot without labor and freight charges. This represents an
initial investment of several thousand dollars, which is simply too much for some small farms.
Although most growers are able to pay for their tunnels within a few growing seasons, others
cannot justify the investment. For this reason, extension and research personnel at the University
of Kentucky have been working on developing a low cost high tunnel covered with a single layer
of plastic that can be assembled or moved in an afternoon.
This low cost high tunnel only provides about 3 oF in frost protection, compared to 7 oF for a
double poly tunnel. This tunnel design has proven to withstand 60 mph winds with little damage
in central and western KY. This tunnel will not withstand much more than a very light snow
event (<1 inch), however it is not meant to be used through the winter in parts of the country that
receive significant snowfall. The best time to use this tunnel is for a few months in early spring
and mid-fall that receive low daily temperatures and mild frosts. Demonstrations in Central and
Eastern KY have shown that growers can reach the market up to three-four weeks earlier with
tomatoes grown in this tunnel than in the field. The added income from these early tomatoes
more than offsets the initial costs.
Additional benefits from this type of design include the ability to make the tunnel as long as is
necessary. Because much of the labor is in constructing the endwalls, there is not as much
difference in labor costs for constructing a 300 foot long tunnel compared to a 100 foot long
tunnel. Obviously materials costs are more, but it allows flexibility for the grower depending on
market conditions. Another positive for organic growers in particular is the ability to easily
disassemble the tunnel and move it from one location to another. One of the central tenets of
organic agriculture is the idea of crop rotation. Unfortunately with some of the more permanent
high tunnel structures proper rotation is difficult. Often growers find themselves growing the
same crop in the same location for many years. Failure to rotate annual crops does not comply
with organic requirements, and in many cases results in high levels of soil-borne diseases.
Organic growers in particular have had to adapt to find creative ways to deal with these diseases,
including grafting of resistant rootstocks, biofumigants, and soil solarization. Being able to
quickly move a tunnel allows growers to easily rotate and avoids many of these problems. The
following are step-by-step instructions on how to assemble this type of tunnel. This design is
constantly being modified to find the most economical use of money and labor while still
providing a sturdy useful structure. Below is a detailed outline on how to construct this tunnel.
Constructing the high tunnel

In this tunnel we have already laid plastic in the field and transplanted. By assembling the tunnel
over the already formed beds we can use traditional tractor mounted bedshapers and
transplanters, saving the need for specialized equipment. Here anchors are made from one inch
diameter pieces of steel pipe 18 inches in length with a single turn of auger flight welded to the
end. Photo credit: Tim Coolong, University of Kentucky

These anchors are placed on eight foot centers the entire length of the tunnel. Generally they are
spaced 12 feet apart, which is enough to easily cover two beds made on six foot centers. Photo
credit: Tim Coolong, University of Kentucky

The anchors are then augured into the ground with a small hydraulic driven motor which can be
hooked to a tractor. Anchors are driven into the ground so that the "hook" that is welded on the
side is just at the soil level. Photo credit: Tim Coolong, University of Kentucky

Then 1.5 inch schedule 40 pvc pipe is placed over the anchors. Typically pipe can be purchased
in 20 foot lengths. A 20 foot pipe will form a tunnel 12 feet wide at the based with a center
height of just over six feet. Pipes should be painted with a latex paint. Experience has shown
that non-painted pipe may cause plastic to degrade where it comes in contact with the pipe.
Photo credit: Tim Coolong, University of Kentucky

Endwalls were constructed the previous season. These are made from 2x4 lumber and have a
number of aluminum channels attached to them for fastening plastic. They are quickly put in
place and attached to the end loops. In addition, ropes are run from either side of the door to

anchors that are sunk deep into the ground. Mobile home anchors are inexpensive and work well
for this purpose. Photo credit: Tim Coolong, University of Kentucky

A lightweight metal pipe is then attached to each bow using aluminum cross connectors. A
typical source of pipe would be the top rail for a chain link fence. This pipe is very important as
it gives the entire tunnel rigidity. Demonstration plots showed that tunnels with the center pipe
withstood very strong (60 mph) wind gusts while those without the pipe did not. The rigid pipe
also helps shed water after rains. Photo credit: Tim Coolong, University of Kentucky

Ropes are then attached to anchors at each end and attached to the first three bows on either end
in crisscross fashion. These ropes help tighten the tunnel and improve end-wall stability. Photo
credit: Tim Coolong, University of Kentucky

Plastic is then unrolled and pulled over the house. Because the plastic is meant to be removed
during the winter months, a lighter weight (4 millimeter) plastic can be used if desired.
However, 6 millimeter plastic has shown to be able to withstand wind to a much greater extent
than 4 millimeter in central KY. Once pulled over the hoops, the ends of the plastic are attached
to the endwalls using "wiggle wire" put into the pre-fastened channels (shown in the far right
photo). Photo credit: Tim Coolong, University of Kentucky

Then nylon rope is fed back and forth over the plastic attaching to the hooks that were welded on
the side of the anchors. The rope is sent down the tunnel and attached to every other hook then it
is brought back up the tunnel and attached to the remaining hooks. The rope is twisted at each
hook so that the rope can be easily tightened as needed. By using the rope to hold the plastic
cover down, one does not have to permanently affix the plastic to any base. Therefore when
warm weather strikes the plastic can be pulled up on each side easily venting the crop inside. In
fact, this type of structure was used to grow organic colored bell peppers during the summer in
Lexington, KY. It served to keep rain off of the peppers, reducing fruit rot and the spread of
bacterial spot of pepper. Photo credit: Tim Coolong, University of Kentucky

Total assembly time for a 160 foot long tunnel from start to finish can be done with 2-3 people in
about 3-6 hours, depending on experience level. The end walls would take an individual about 2
hours each to build. While these tunnels only give about 2-3 oF of frost protection alone-more if
an additional layer of plastic or remay is placed in the tunnel, they effectively increase the
number of hours above 50 oF when used in spring. Thus they promote rapid growth and early
fruit when used for tomatoes. Above is a picture taken on June 20, 2008, in the mountain region
of East KY. The plastic had been removed, but one can easily see the difference in growth and
fruit set on the tomatoes 'Mt. Crest' planted in the tunnel and those outside the tunnel. Both were
planted on the same day in late April 2008. While not for everyone, these inexpensive tunnels
can give growers a jump on the season without a large investment of capital. Photo credit: Tim
Coolong, University of Kentucky

This is an eOrganic article and was reviewed for compliance with National Organic Program
regulations by members of the eOrganic community. Always check with your organic
certification agency before adopting new practices or using new materials. For more
information, refer to eOrganic's articles on organic certification.

High Tunnels in W.Va.
By Lewis W. Jett, Horticulture Specialist, 2010

Figure 1. High tunnels are passively vented, solar greenhouse structures covered with a single or double layer of polyethylene plastic

High tunnels are passively vented, solar greenhouses that are used to lengthen the production and marketing season of vegetable and fruit crops
(Figure 1). No artificial heating/cooling or ventilation system is used within the high tunnel, and the only external connection is water for drip or micro-
irrigation. Most high tunnels are covered with a single or double layer of polyethylene plastic (6-mil; greenhouse-grade) and have a useful life of 20
years if properly constructed and maintained. Crops within high tunnels are usually grown directly in the soil rather than artificial growing media, but
soil-less substrates (perlite, compost, water) can be used for crop production within high tunnels.
High tunnels are very effective in collecting radiant energy from sunlight and using this energy to increase air and soil temperature to accelerate crop
growth. Thus, in areas with abundant sunlight, high tunnels will be very effective for early-season harvest and lengthening the growing season.
High tunnels facilitate intensive crop production on a small land area and are conducive to sustainable farming practices such as intercropping, cover
cropping, compost application and biological pest management. Crops within the high tunnels are protected from environmental stresses such as
drought, wind, hail, rain and intense sunlight. Heavy rainfall prevents soil erosion within the high tunnel. The dry environment within the high tunnel
keeps the plant canopy dry and reduces diseases and weed growth. High tunnels also physically exclude many pests from attacking the crop including
insects and wildlife. As a result, many growers use high tunnels for organic production of fruits and vegetables. High tunnels have significantly lower
investment costs and annual operating costs than standard greenhouses.

Figure 2. The site for construction of a high tunnel should be accessible, well-drained with abundant sunlight. (Photo Credit: E. Coleman)

The first step in high tunnel crop production is choosing a suitable site for the structure (Figure 2). Most high tunnels are permanent structures, so the
site chosen will be the area for crop production for several seasons. Depending on location, building permits may be required. The site should have no
history of perennial weeds or diseases and be well-drained and free of large stones. A soil test should be conducted in advance of choosing the site for
the high tunnel. Since high tunnels are manually vented, they should be accessible. Water is an essential input for high tunnels, so access to water
(surface or well) is necessary. While most high tunnels do not require electrical inputs, some growers choose to have electric fans which circulate air or
inflate air between double layers of polyethylene.
High tunnels do not have to be constructed on perfectly level land, but a building pad or terrace can be made prior to constructing the high tunnel.
Slope along the length of the high tunnel will facilitate water movement but should not be greater than 3%. Slope across the width of the high tunnel
can be compensated by adjusting the height of the ground posts on either side. The construction pad can have sloping sides to channel water and
snow runoff from the high tunnel structure.
The site should have full sun and good air flow since these are essential inputs to how well a high tunnel functions. Low areas that accumulate cold air
(frost pockets) and water or sites close to a tree line or other structures which may cast a shadow on the high tunnel structure should be avoided. Also,
areas with strong wind should have a wind break to prevent excessive wind stress or snow accumulation against the structure.
Orientation or positioning of the high tunnel is site dependent. The primary criterion should be maximizing passive ventilation. Therefore, for suitable
ventilation, the high tunnel should be oriented so the length of the structure is perpendicular (i.e., at right angles) to prevailing winds at the site. In West
Virginia, a north-south orientation is optimal for cross ventilation. Above the 40° latitude, most high tunnels are oriented in an east-west direction for
maximum light interception particularly during low light months of winter. Most of West Virginia is below 40° latitude, so orientation is based on
maximizing cross ventilation. Generally, the strongest winds which can damage the structure occur from the north-northwest in West Virginia, so a
north-south orientation allows this potentially damaging wind to hit the smallest surface area of the structure (i.e., the end wall).

Figure 3. Quonset- (top) and Gothic- (bottom) shaped high tunnels.

High tunnels vary in length, width and shape. Ideally, the high tunnel should be at least tall enough to walk in with ease (> 7 ft.) or for equipment to be
taken into the structure to till the soil, apply compost or create raised beds. Most high tunnels are 15-30 feet wide; 9-15 feet high and up to 200 feet in
length (Figure 3). Optimal length for an individual structure with roll-up sides is approximately 100 feet. Many growers will start with a short, wide
structure (e.g., 30 ft x 48 ft) and add on to the length in subsequent years. A shorter, wider structure is superior to a longer, narrower structure since
the former will have less area exposed to the outside environment.
Larger high tunnel structures tend to store more heat during the day and are less likely to overheat. At night, when maintaining a stable temperature is
crucial, larger high tunnels are less likely to cool down as rapidly. In addition, a taller high tunnel allows warm, buoyant air to rise in the structure
facilitating ventilation.
There are two main structural designs for high tunnels: Quonset and Gothic. Quonset structures have a round roof with slightly shorter and curved
sidewalls (Figure 3, top), while Gothic structures has a pointed peak (A-frame) with straight sidewalls (Figure 3, bottom). Gothic structures tend to shed
snow and ice better than Quonset structures. Gothic structures also allow for a peak or gable vent to be added to the structure which facilitates air
movement and ventilation.

Figure 4. (top) Sidewalls are rolled-up to facilitate cross-ventilation within the high tunnel. (bottom) PVC-framed high tunnels are functional high
tunnels.

Sidewalls on the high tunnel structure are usually rolled-up to facilitate cross ventilation (Figure 4, top). Therefore sidewalls should be at least 5 feet in
height to maximize ventilation. During inclement weather, the sidewalls are closed.
If the site for high tunnel construction encounters significant snow or wind stress throughout the year, cross-braces (bracing of the bows) or other
supplemental bracing of the frame may be necessary to strengthen the structure. Frames for high tunnels are usually galvanized steel but other
materials can be used. Wood frames have been used as framing material for high tunnels. However, there is more blockage of sunlight from the wood
frame than by other framing materials. Polyvinyl chloride (PVC) has also been used as a framing material for high tunnels (Figure 4, bottom). Most
PVC-framed high tunnels are smaller in width than steel-framed structures. While PVC high tunnels can be lower in costs, they tend to be vulnerable to
damage from wind, snow and ice unless they are properly braced.
After the site and general design of the high tunnel has been chosen, the structure can be constructed. Both spring and fall are excellent times of the
year to build a high tunnel. The soil is amenable to construction, and the air temperature is suitable for pulling and stretching plastic over the structure.
If building on a site which is presently in sod, the sod can be tilled after most of the high tunnel has been constructed.

Figure 6. The high tunnel structure must be square at each corner post.

The next step is to place the corner ground posts of the high tunnel so that the structure is ultimately square. The Pythagorean Theorem can be used
to establish a 90° angle at each corner. The Pythagorean Theorem states the square of the hypotenuse of a 90° triangle is equal to the sum of the
squares of the other two sides. Once one corner is square, the other three corner posts can be set so that the diagonals (length from one corner post

to the opposite end corner post) are equal (Figure 6). For example, a 30 ft x 96 ft high tunnel will have a 100.5 ft length diagonal (302 + 962) if the
structure is square.

Figure 7. Corner posts can be set in cement to provide strength for the high tunnel structure. A leveling line is used to ensure each ground post is
level. (Photo credit: A. Montri)

After the corner posts have been squared, they can be backfilled with cement to provide support for the structure (Figure 7). Obviously cement makes
the structure permanent, so if there are plans to move the structure in the future, this step may be avoided. The remaining high tunnel ground posts are
driven into the soil as straight as possible to various depths (usually no less than 18 inches) with a sledge hammer or post driver. A post level will be
very useful in making sure each post is plumb. Also a leveling line (mason twine) connected to the bolt holes of each corner post can be used to drive
each post to a depth which is level. A positioning or spacing jig can be used to evenly space the ground posts. Most ground posts are placed 4, 5 or 6
feet apart, with 4 feet the recommended spacing for high tunnels in West Virginia.

Figure 8. Purlins, cross braces, base boards and hip boards are attached to each bow to provide stability to the high tunnel frame.

The bows of the structure typically are 2-3 pieces and can be loosely assembled on the ground. Each bow is then inserted into the ground post and
secured with 1-2 carriage bolts. Placing each bow in the ground post will require approximately 3 workers. After the bows are secured in place, the
purlins should be attached to the bows. Purlins are smaller diameter pipes which are bolted (or clamped) to the bows to provide stability to the structure
(Figure 8). Each high tunnel frame should have 1-3 purlins. Cross-braces can be attached to provide increased strength to the high tunnel frame.
After the purlins have been added to the structure, the baseboards and hipboards can be placed on the high tunnel. Baseboards and hip boards add
strength to the base of the frame (Figure 8). For most high tunnel frames, 2 inches x 6 inches x 10 feet wood (or recycled plastic) boards are suitable.
Pressure treated wood can be used for both hipboards and baseboards. Each section of baseboard is bolted onto the ground post or secured with a
pipe strap (Figure 9). The baseboard and hipboard must be level across the length of the high tunnel. Each joint between sections can be spliced with
a small segment of board.
Hipboards are attached 5-8 feet above the baseboards (Figure 8). Hipboards provide additional strength to the structure and are the boards in which
the plastic covering the high tunnel structure is attached. Aluminum channel lock can be secured to the hipboard to provide a location for securing the
plastic (Figure 9).

Figure 9. Pipe straps are used to secure the baseboards and hipboards to the high tunnel frame. Aluminum channel lock is used to secure the plastic
to the frame.

After the frame has been assembled, the end walls can be constructed. End walls vary in design from a simple fabric curtain to a wood-framed
structure with doors (Figure 10). End walls provide strength to the high tunnel and should be built to provide easy access of people and machinery. End
walls can be covered with polyethylene plastic, polycarbonate or plywood. The north-facing end wall can be covered with double layer of polyethylene
plastic to provide greater protection from the north wind. Some growers will completely remove the end wall coverings during warm weather.

Figure 10. There is a diversity of end wall designs for high tunnel structures.

The plastic covering can be placed over the high tunnel structure after construction of the frame and end walls has been completed. There are many
types of greenhouse plastics, but the plastic should be a UV- (ultraviolet light) treated plastic, 6 mil in thickness, with a useful life of approximately 4
years. IR (infrared) blocking plastic is also available and will provide better heat retention. A calm day with moderate temperatures will be optimal for
covering the structure. Plastic should not be pulled over the structure if temperatures are lower than 60° F since it will be difficult to obtain a good
stretch on the plastic. Ideally, the plastic should be taut and not flap against the bows.

Figure 11. Plastic (poly) is used to cover the high tunnel structure. The plastic is pulled over the frame after securing it with rope wrapped around
tennis balls.

At least 4-5 people will be needed to pull the plastic over the high tunnel. The plastic comes in a roll which is unrolled along the length of the house
(Figure 11). After unrolling the plastic, a handful of the plastic can be folded around a tennis ball at various distances. Rope is then tied to this ball and
thrown over the frame (Figure 11). Carefully, the plastic is pulled over the structure, making sure it is square with the frame.
The plastic is attached to the frame with wiggle wire or polylock placed in each aluminum channel lock on the hip board (Figure 12, left). One side
should be completely secured first then any slack in the plastic can be pulled and the other side wired. The plastic should be as taut as possible. The
channel lock on the end bows are used to hold the plastic to the end walls of the high tunnel. The plastic is clamped on to a metal roll bar (purlin pipe)
which serves as the bar for rolling the plastic up or down on each side wall. A “T- or L”- shaped handle can be made to serve as a hand crank which
makes rolling the pipe up easier. Rope can be laced on the sidewalls to hold the plastic sidewall closer to the frame and prevent flapping in wind
(Figure 12, center).

Figure 12. (left) Plastic is secured to the frame with wiggle wire within each channel lock. (center) Rope can be laced along the sidewall for tightening
the roll-up sides. (right) Water runoff from the high tunnel can be collected and used for irrigation.

To prevent excessive water movement into the high tunnel, a drainage ditch should be dug to channel water away from the high tunnel. A woven
landscape fabric can also be used to divert excess runoff water and prevent weeds from growing close to the high tunnel. Rain gutters can also be
secured to the hipboard and used to channel water into a storage tank that can be used to irrigate crops within the high tunnel (Figure 12, right). Batten
tape can be used to secure the plastic to the end wall frame. Batten tape is applied over the plastic and stapled into place.
Additional High Tunnel Construction Resource Material:
The Hoophouse Handbook. 2003. Growing for Market. L. Byczynski (ed.).
The Winter Harvest Handbook. 2009. E. Coleman. Chelsea Green Publishing Co., White River Junction, VT

High Tunnel Production Manual. 2008. Penn State Center for Plasticulture.

Yard & Garden Line
News
Volume 6 Number 15 September
15, 2004

Features this issue:
High Hopes for High Hoops
Golden Rust on Goldenrods
West Nile Virus Cases Down
Incorporate All-America Selections into Next Year's Garden
Late September Garden Tips
Editorial Notes

High Hopes for High Hoops
Robert Olson, Regional Extension Educator, Horticulture

This summer's dismal weather has
prompted a lot of interest in garden
structures that extend the growing season.
Tops on this list are "high hoops" - also
called "high tunnels" or "hoop houses".
There names are interchangeable, and
they've become the most popular form of
greenhouse structure for many reasons.
M
a
High hoops were originally designed for j
commercial growers, but their popularity o
has lead to the development of smaller r
structures that are being utilized by
c
backyard gardeners. Regardless of size, o
the working principles are the same. m
p
What are they? o
High tunnels are unheated, plastic- n
e
covered structures that provide an n
intermediate level of environmental t
protection and control as compared to s
open field conditions and heated
greenhouses. Plantings in high tunnels are I
l
placed directly into the existing soil of l
your farm field or garden, as opposed to u
production on benches or raised platforms s
like in greenhouses. :
P
e
High tunnels are tall enough to walk in n
comfortably and to grow tall, trellised n
crops. Homeowner models that are 14 feet
wide reach an interior height of about 8 S
feet; commercial models that are typically t
a
30 feet wide reach a height of about 15 t
feet. The commercial models also have e
end panels that allow small tractors to
drive through.

Greenhouses are permanent structures that
are taxed as real property, whereas high
tunnels (being temporary, moveable
structures) are not. Greenhouses are
covered by glass, rigid panels or double-
layer plastic, but high tunnels are covered B
with a single layer of plastic. a
s
i
A critical component of high tunnels is c
their ventilation system which generally
s

consists of roll-up sidewalls that can be opened in the morning and rolled down at night or in
cold weather.

Because the entire system is enclosed, no rainfall enters the tunnel. All water is supplied by the
grower, generally via trickle tubes that are placed under plastic. The interior of the tunnel is
completely dry and relatively clean. Harvested produce is very clean, greatly reducing the
washing of produce. Research validates that fresh produce from tunnels also has enhanced shelf
life as compared to field-grown produce.

Unlike commercial greenhouses that can cost up to $20 per square foot to construct, high tunnels
can cost as little as $0.50 per square foot. This modest cost can result in a high return on
investment, and in a season like this year growers with high tunnels reported that they paid for
themselves the first season. Proponents of the tunnels see them as great income-generating
technologies that college students and enterprising high-schoolers could manage as a summer
job. One commercial-scale tunnel (30 feet X 90 feet), costing under $2000 to construct, could
gross over $6000 if planted to tomatoes that are sold at farmer markets or roadside stands.

Unexpected Benefits
Everyone expected tunnels to provide a heat advantage compared to field-grown production.
Few people, however, expected the dramatically reduced pest levels that are being realized.
Growers and researchers alike are impressed with the excellent weed, insect, and disease control
within the tunnels. Growers that have been cautious about organic production are now giving
organics another look.

Reduced disease One of the most impressive features of these systems to date is the diminished
disease pressure. The tunnel systems, by keeping the interior completely dry, result in an
environment less conducive to several of the problematic disease organisms. Think about it, the
foliage is always dry and there is no soil splashing compared to field grown systems. Add to this
the wind protection factor from blowing soil and the enhanced vigor of plants, and you have an
environment that allows crops to out-compete pests.

A critical component to managing diseases is the sidewall ventilation system. Without the open
sides, the humidity levels would lead to a rainforest environment and subsequent disease haven.
So during most days, the sidewalls are rolled open. When nighttime comes, the grower closes the
tunnel to keep the cooler evening air from condensing on the leaf surfaces, thereby keeping the
foliage completely dry. Just walk your lawn in bare feet after sundown and you'll know just how
wet foliage can become. I'm reminded about condensation every winter morning when I scrape
the ice from my car's windshield, whereas the cars parked in the garage are nice and dry. It
makes me wonder, why is it that I am the one who pays for the cars, the insurance, the mortgage,
and puts gas in the cars, yet I'm the one who has to park outside in the cold? I digress.

More Information
If your interest is piqued, you'll probably want to do a little research on the subject. My
colleague, Terry Nennich, is developing a written manual on high tunnel management based on
Minnesota research which will be designed for commercial growers. The principles will be
applicable to the backyard gardener as well. Another great source for information is Penn State,
which has a large research effort devoted to plasticulture, including high tunnels. They can be
accessed at: http://plasticulture.cas.psu.edu/.

Golden Rust on Goldenrods
Janna Beckerman, Extension Plant Pathologist

This year has been an interesting one for
plant pathologists. As our long, cool wet
spring, became a cool, dry summer, a
variety of diseases that are commonly
overlooked became unusually severe. One
such disease is pine needle rust. However,
the severity of this disease manifested S
itself most severely on the alternate hosts: e
Goldenrod (Solidago spp.) and Aster v T
(Aster spp.) e o
r
e m
When forest pathologists discuss pine
a
needle rust, they refer to the economically i k
important timber hosts of jack (P. n e
banksiana), Austrian (Pinus nigra), red (P. f
resinosa), ponderosa (P. ponderosa), e s
c u
mugo (P. mugo), and Scots (P. sylvestris) t r
pine. Economically speaking, the alternate i e
hosts are of little value-except to the o
homeowner whose plant is suddenly n t
orange. This disease is caused by the h
o e
fungus Coleosporium asterum. Although n
it doesn't look that way, this rust causes d
little damage on either host. In pines, g i
browning and needle death on lower o s
branches is unattractive, and may slow the l e
d a
growth of young pines. On goldenrod and e s
aster, severe infection may result in a n e
reduction or loss of flowering. r
o i
The life cycle of pine needle rust takes an d s
.
entire year to complete. Currently, on the
r
aster and golden rod, we are seeing the u
uredinia developing on the leaves and s
stems. This stage can repeat itself under t
conducive weather conditions, and render ,
the entire plant orange, as we've seen! c
h
Eventually, urediniaspores produce a new e
spore shape, the teliospore. The c
teliospores germinates to produce k
basidiospores that are windblown to pine
needles, where new infections begin. y
I o
These infections will not be seen until n u
next spring. d r
i
In the meantime, the fungus survives v h
winter in the infected pine needles. The i a
d n
u d

following spring, small yellow spots appear on infected needles that develop into columns that
split releasing orange spores. These spores are wind- dispersed and infect the underside of leaves
of the goldenrod and aster. Orange structures called uredinia develop on the leaves and produce
the characteristic orange spores that we are seeing now.

When diagnosing rust diseases, it is important to actually see spores! Plants turn orange for many
other physiological reasons (nutrient deficiency, insect feeding, herbicide damage, etc.). Finding
spores on your hands is a tell-tale sign to diagnose this disease!

Although pine needle rust rarely causes damage to mature trees, it can render plantings of asters
and goldenrod unbelievably orange. Fungicides labeled for the control of rust on perennials
contain active ingredients like sulfur, chlorothalonil, myclobutanil, and mancozeb. Replacing
plants with rust resistant asters Removal of alternative hosts from the immediate vicinity of the
trees will reduce infections of pines. Cultural practices such as thinning foliage, watering during
dry periods, mulching, and fertilizing may reduce infections. Reportedly resistant goldenrod
cultivars include: 'Baby Sun,' 'Baby Gold' and 'Goldkind.' The PREP trial in Rosemount has
found that Aster 'Alma Potshke' was very resistant to rust, but that the A. dumosas series 'Wood's
Pink' and 'Wood's Purple' were very susceptible and susceptible, respectively.

Please check out the new diagnostics web pages at
http://www.extension.umn.edu/projects/yardandgarden/diagnostics/

West Nile Virus Cases Down
Jeffrey Hahn, Assist. Extension Entomologist

Although many Minnesotans will think of
2004 as the summer that never was, we
may also remember it for the low
incidence of West Nile virus (WNV) that
we experienced. Our first detected activity
of WNV in Minnesota occurred in 2002
when we recorded 48 human cases and D
i
zero deaths. In 2003, the number of s
human cases tripled to 148 along with e
four deaths a
s
The big question was what would happen e
in 2004. Would the number of cases o
continue to increase? Unfortunately, u
entomologists and vector ecologists don't t
know enough about this disease to b
accurately predict how the disease will r
e
cycle. But fortunately instead of a
continuing to go up, the number of WNV k
cases have fallen. So far this year, there s
have been only 19 cases and one death
recorded in Minnesota (as of September I
m
14, 2004). Although more cases are likely a
to be reported before the end of the year, g
(most cases in Minnesota are reported e
during August and September) the :
majority have undoubtedly occurred. C
D
C
Interestingly, the number of horse cases
this year are also considerably down. To
date, there have only been 6 instances of horses infected with WNV. This is after 992 cases in
2002 and 74 cases last year. Although there may be several factors that help explain this, much
of this decrease is probably attributable to the increased protection of horses that owners have
given them, especially by vaccinating them.

However, there is not such an easy answer for humans to explain why the incidence of WNV has
gone down. It is natural to assume that the cooler weather had a significant effect on WNV cases.
While it is true the weather probably did slow down mosquito activity, it is unlikely the only
reason. There does seem to be a consistent trend in other states for the rates of WNV to cycle
down after a large increase of WNV has been first detected, although the exact reasons are not
clear.

It is interesting to look at New York, the first state to record WNV. In 1999 they detected 62
human cases of WNV with seven deaths. Those numbers went down in 2000 to 14 cases, zero
deaths and to 15 cases and two deaths in 2001. The number of human cases rose in 2002 to 83
(five deaths). In 2003, activity was down to 71 cases but with 10 deaths. So far in 2004 there
have been only 5 cases with no deaths. Although the incidence of WNV may go up, it always
seems to come back down to very small numbers. (Keep in mind that for a state with such a large

population as New York, 100 or fewer cases is just a small percentage of the overall population).

There isn't an easy explanation for this pattern in New York or similar cycles in other states,
including Minnesota. That makes it difficult to predict whether the current trend in Minnesota
will remain in a downward cycle or fluctuate. The disease is too new here to understand it
completely. We need to continue to learn about WNV to better understand what our potential
risk may be.

For more information, see also the Minnesota Department of Health West Nile virus web site,
http://www.health.state.mn.us/divs/idepc/diseases/westnile/index.html

Get the low down on this month's insect pests at Insects
http://www.extension.umn.edu/projects/yardandgarden/EntWeb/Ent.htm

Incorporate All-America Selections into Next Year's Garden
Deborah Brown, Extension Horticulturist

It's always fun to try new seeds, and when
the flower or vegetable is an All America
Selection winner, it's a pretty good bet
that it will perform well in your garden.
Here's a sneak preview of the All America
Selections chosen for 2005. You should T
be able to order seeds from a number of o
mailorder or Internet catalogs. Some m
winners will also be available as young a
G t
transplants in packs at local nurseries and a o
garden centers. l
l '
a S
Flowers: Gaillardia ‘Arizona Sun,' also r
known as "blanket flower," is a neat, u
d g
compact cultivar suitable for container i a
growing. Blanket flowers are usually a r
short-lived perennials in our climate. y
' '
Should you hope to over-winter it, plant it A
in the ground rather than in a container. A
r l
i l
Catharanthus ‘First Kiss Blueberry,' z P
usually called "vinca," is the bluest yet o h
n o
produced, but it's still a violet-blue rather a
than sky blue. Vincas have glossy, t
o
leathery leaves and can take sunny, hot, S s
dry conditions. They also bloom in light u :
shade, though not as well as in a sunny n A
' A
site.
S
Zinnia ‘Magellan Coral' produces double
flowers, five to six inches across! It
blooms early – only six to nine weeks
from seed – and, like other zinnias, grows
best when seeded directly into the garden.

Vegetables: ‘Fairy Tale' eggplant is pretty
enough to categorize with the flowers
V
instead of the vegetable winners. The i
petite plants produce small purple and n
white striped fruit that are tender and tasty c
when anywhere from one to four ounces a
in size.
'
F
‘Sugary' tomato produces grape-like i
clusters of ultra sweet "cherry" tomatoes r
that are oval, with a little point on the end. s
They can be harvested about sixty days t
K
i

after transplanting, and may be grown in large containers or supported, directly in the ground.

‘Bonbon' is a winter squash with an upright, semi-bush habit, requiring less garden space than
most winter squash. The boxy, four pound fruits are said to have superior eating quality – sweet,
with a creamy texture. They ripen roughly eighty-one days from planting, sometime the latter
part of August in southern Minnesota.

Late September Garden Tips
Beth Jarvis, Yard & Garden Line

Compiled from conversations with Patrick Weicherding and Bob Mugaas, Regional Extension
Educators.

These recommendation are based on Twin Cities temperatures. Adjust for northern
Minnesota.

Trees and Shrubs:
Water trees, especially those 5 years old or less. Older trees, theoretically, could be damaged by
heavy watering because it could prompt new growth that can't be supported by drought-damaged
roots. However, recent substantial rains will lighten the drought stress on established trees,
especially since they're shutting down in preparation for winter. Soil moisture is an important aid
in the development of the abscission layer, so the rain will help the leaves fall. Drought stressed
trees will hold leaves well into the winter.

Water all evergreens and young trees until the ground freezes. Water deciduous trees and shrubs
as best you can until the leaves fall. Remember that lawn grass captures the vast majority of
applied moisture, so water more than an inch within the dripline of trees. The soil should be
damp at least 6-8". Plase see: http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-
Sept0103.html#water"

Early fall color is a drought response indicating that the trees can't support the leave they still
have. Poplars/cottonwood and ash are typical leaf "shedders" when stressed. Maples are another
issue--that's maple decline--when trees are so stressed they can't recover.

Pruning for cosmetic or structural purposes should wait until the dormant season. Remove
diseased trees now. Be sure all elm firewood has been de-barked before storage.

Hold off on pruning trees susceptible to fire blight right now. Wait until late winter. The most
commonly affected are: pear, apple, crabapple, mountain ash and cotoneaster. Read about it at:
http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/p223fireblight.html

Shop fall tree sales. Pick well shaped trees with wide branch angles where applicable, and
desired fall color. Plant in the ground by the middle of October.

Start thinking about rodent protection of new trees--it should go on before November 1, so shop
around for 1/4" hardware cloth to surround tender-barked young trees.

Lawns:

It's a great time for perennial broadleaf weed control.

We're coming up to the tail end of seeding, though if it stays warm and rains, the rest of
September could be suitable. Sooner rather than later is the key as grass needs to be established
before winter's cold arrives.

Sodding can be done for another month or so.

If you overseed, work up the soil so you get good soil to seed contact. Tossing seed on a thatch-
covered lawn will accomplish nothing.

You can start reducing mowing height. A 3" cut can be reduced to 2.5". This will reduce
floppiness that can help reduce future snow mold problems and increase growing points/density
of plants.

Be sure to water if we get into a dry spell, even though temperatures may be cooler.

Wait until closer to the end of October for the late season fall fertilizer application. If your grass
is a bit anemic now, a half pound of nitrogen per thousand square feet of lawn could be applied
now followed by the late fall fertilizer application of a full pound of nitrogen.

Core aerating is still possible. Dethatching should wait until spring. If you have heavy thatch, do
a a real thorough core aerating job now. Grass needs 6-8 week of recovery time.

Everything you ever wanted to know about lawn care and repair can be found at the Sustainable
Urban Landscape Information Series website at: http://www.sustland.umn.edu/maint/index.html.
Click on lawn maintenance and scroll down to the lawn care calendar for timing.

Flowers:
Plant spring flowering bulbs soon. All but tulips need to be planted early. Tulips can be planted
as late as you can dig in the ground. For more info, see Spring Flowering Bulbs
http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/h120bulbs-spring.html

As plants yellow and die back, it's ok to cut them back and compost any healthy plant tissue.

Editorial Notes

Joe Pye weed is noted for growing taller
in the wild and staying shorter in
cultivation. It could be a light issue, as
wild plants may be trying to grow into
more light. This photo, taken at Eloise
Butler Wildflower Park many years ago,
was in an opening in the woods and quite J
tall. o
e
In the next issue, Bob Mugaas, Regional P
Extension Educator, Horticulture, will be y
writing about why lawns flower and set e
seed in the spring. The process starts in
the fall. That will be published Oct. 1. I've w
e
asked a couple of grad students to write a e
piece on the physiological changes plants, d
other than turf grass, undergo in order to
flower. In the future, Patrick Weicherding, i
Regional Extension Educator, Forestry, n
will be writing about new research w
findings on the timing of pruning trees for i
disease prevention and to prevent pruning l
damage. d

P
Please feel free to cut and paste any of the h
articles for use in your own newsletters. o
All we ask is that you give our authors t
credit. o

c
Back issues Yard & Garden Line News
r
are on the Yard & Garden Line home e
page at d
www.extension.umn.edu/yardandgarden/. i
t
:
B
Deb Brown answers gardening questions e
on Minnesota Public Radio's (MPR) t
"Midmorning" program on the first h
Thursday of every month at 10 a.m. The J
program is broadcast on KNOW 91.1 FM, a
and available state-wide on the MPR news r
v
radio stations. i
s
For plant and insect questions, visit
http://www.extension.umn.edu/askmg.
Thousands of questions have been answered, so try the search option in the black bar at the top
left of the board for the fastest answer.

If you would like to receive an e-mail reminder when the next issue of the Yard & Garden Line
News is posted to the web, just send an e-mail to: listserv@lists.umn.edu (note: the second E in
listserve is omitted), leave the subject line blank, then in the body of the message, type: sub
yglnewslist or to unsubscribe, enter: unsub yglnewslist

Happy gardening!

Beth Jarvis
Yard & Garden Line Project Coordinator

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Building a High Tunnel Hoop House / Green House : Part 1
B Y ANDY, ON MARCH 21ST, 2011

Quite a while back we asked for input on Facebook from everyone to see what YOU would do if you were out here on the
farm… the question was – would you buy a JD Gator or would you buy a greenhouse? The results were split 50/50 so we
knew we needed to make both happen. As you know – the Gator transaction was completed a while back… As for the
green house / hoop house… well, construction started this weekend. The process is actually very straightforward and we
are moving through the steps at a pretty rapid pace. Basically we bend all the tubing we need for the hoops, we pound
some slightly larger diameter tubes about 4 feet into the ground, screw the arches together and slip the arches into the
tubes. We start with standard line posts for a chain link fence and cut them into 4′ lengths with a metal cutting blade on
the 12″ chop saw.

The tools for pounding the tubes into the ground are pretty simple and with the ground being so wet right now the process
is actually pretty easy. First we marked off the house with string in a 12′ x 28′ rectangle. Then using a mallet the post
gets pounded about 6″ into the ground. The level and the big post driver help get it father down and straight too. The
last 6″ takes a sledge hammer… that tends to round over the top of the pipe in the ground but as long as the 1 3/8″ pipes
for the hoops fit we are OK. If the opening gets too small, we use a bar to pry open the rolled metal. Very simple process
actually.

To bend the tubes we mounted a 3/4″ sheet of plywood on the back of our Gator and then mounted the tubing bender to
that. Then it’s a little elbow grease and a lot of back pulling to make the straight tubes that were bought at Home Depot
for chin link fencing into the curved halves of the hoop structure. Once we got the mechanics worked out I can feed and
bend and Kelli can pull and keep the tube flat. It takes about 30 seconds to bend half a hoop.

After bending the tubes Kelli removes them from the opposite end of the device and then stacks them in the barn. The
ends are painted to match the corresponding other half of the arch so when they go out to the field we know which ones
go together. To build this particular structure we need 28′ of support which is one arch every 4′… so that’s 7 arches, plus
one for the end… and 2 bars per arch… calculator says… 16 total tubes bent.

The last step is the most rewarding… inserting the ends of the arches into the tube in the ground. The arch (or hoop –
that’s why they call these a hoophouse) measures about 14′ wide when it’s not flexed so we “squeeze it” down to 12′ to

make the hoop house structure. The insertion of these hoops under tension adds a great deal of strength to the finished
structure.
As it sits now you can see we installed a single hoop mainly to feel good about our efforts… but to the left of the picture
you see a whole bunch of pipes laying in the weeds waiting to be driven into the ground so we can attach more hoops. We
still need to build the base around the hoops out of some pressure treated 2×8 lumber, install a support along the spine of

the structure, build some ends and then finally install the plastic… that’s ALL.
If you liked this post, check out these:

• Building a High Tunnel Hoop House / Green House : Part 2 - (Really Similar)
• Dampening Off! - (Interesting)
• Gators and Greenhouses and Greenbacks, ohh my! - (Interesting)

B Y ANDY, ON APRIL 10TH, 2011

Just to set the record straight before we get into this… The last post on Pigs Milk Cheese was an April Fools post (nice job
to those who caught the date). Also – if you haven’t ordered your pastured chicken yet – you should.

With the posts in the ground (from the first post) there’s still a fair amount of work to be done,
we needed to get a wooden base around to frame up an attachment point for the double layer of plastic. We also need to
get the hoops installed, the spine installed and then some nifty wind bracing installed so we have a prayer of sustaining
those 60 MPH+ winds we get on the hill here without watching our hard work blow into the next county. So we started
with the base boards. normally people install larger treated 2x something boards – but looking at the price of lumber we
decided to go with a much less expensive treated 5/4×6 non-premium decking board. In reality, these base boards don’t
offer much more that a place to attach the plastic so there’s no need to them to be super heavy duty. They are attached
by drilling a hole through the board and the post and then attaching with a 1/4″ stainless bolt and nut.

The challenge of installing the the base boards is really all about level ground. The posts were driven in to
an approximation of “level” – but adding the base boards required a fair amount of finagling. All said and done, the lower
end of the structure has the baseboard about 4″ above the soil and te high end has the boards about 3″ into the soil. And
we picked one of the more level areas to site the greenhouse!

With 3 sides of the base completed (we left the end with the door open as it cuts through the existing low tunnel AND we
are still debating about making the end door tractor friendly as well) it was time to start to assemble the superstructure,
and all that starts with an end. So, we used the backhoe to dig a couple of 3′ deep holes and dropped some
old treated 2×4′s in. Those were then lined up with the end hoop, cut to length, notched and bolted to the hoop itself.
The spacing for the end posts we determined by the 2 tripple track storm windows that came off the barn when we
resided it. They are big and will provide LOTS of ventilation on the west end of the green house.

Once that “wall” was built, the process really takes off. It becomes an exercise in joining the 2 halves of the hoops we
bent with stainless self tapping metal screws, then inserting them into the posts that are attached to the base boards.
After all the hoops are up, the next step was to use some special (and expensive) clamps designed to attach the spine
down the top ridge line. This addition locks all the hoops into a single structure and really provides a massive amount of
rigidity to the structure. Up until this point we kinda felt like we were kids making a sandcastle at low tide… just waiting
for the wind to pick up and blow out wiggly metal structure into 100 little pieces. But with each rib being attached to the
spine (yes, I loved Moby Dick), the whale of a structure became more and more solid.
After the last section of the spine was installed and cut to length all we had left todo was install a set of diagonal wind
braces and the windows. All in all, the steps in this part of the installation only took about 5 hours over 2 days and were
the most rewarding steps. We can now stand back and look at something that resembles a green house. And the most
rewarding part has been the discovery of how strong this structure really is. The spine and the wind bracing has made the
and wall solid and we really think this structure is going to be able to take the winds. As a matter of fact we are already
thinking of LOTS of ways we can expand this design for something like a roaming pasture warmer for the chickens in the
middle of winter… At any rate, tonight we place the order for the plastic, inflator fan and various other parts. Time
marches on and our seedlings in the basement are getting ready for a nice warm “real sunlight” house!

For a few more pictures of the process – visit our Flickr Photostream to check things out.


B Y ANDY, ON MAY 3RD, 2011

Plastic cover ready!
We finally had enough of a break in the wind and weather around here to do the last of the work on the hoop house / high
tunnel. That “last of the work” would be to install the plastic. A quick search of the web on how to install greenhouse
plastic didn’t really offer a lot of suggestions or help. Further more we knew we were going to be inflating the two layers
of plastic with a greenhouse inflation blower… and that too isn’t well documented out there. So – here’s the tools,
techniques and lessons we learned in the last phase of constructing this greenhouse.

Wiggle wire
First, we decided that the easiest way to attach the plastic was using a wiggle wire system like
most commercial greenhouses. The wiggle wire is a bent piece of stainless steel wire that fits inside a specially
designed aluminum channel – the wire presses and pulls on the plastic and the channel follows the contour of the
greenhouse. The idea is to basically close the plastic over the structure on 4 sides kinda like a big 4 sided Ziplock bag then
pump air into the space between the plastic to create a layer of insulation and keep the plastic taunt so the wind can’t grab
a hold of it and rip it off. Pretty simple system that goes together pretty fast. time will tell how it handles the winds we
get up here!

How do you get plastic on a greenhouse?

The long side
That question was one we couldn’t get a really good answer on. We waited for a calm day (no wind) and then pulled the
plastic layers over the hoops. The inner layer is a infrared reflective layer to keep the heat in at night and the outer layer
is typical greenhouse plastic. Once it’s draped over the structure we picked a corner and started working from there. The
general approach is to close things up like a plastic bag… starting at one side and working our way around. By doing
things like that the plastic can shift and slide as we pull on it and we can minimize wrinkles in the final layout. So, we
started on one of the longest sides by installing the wiggle wire the entire length.
From there we then went up along the end hoop. The only place s the plastic is attached is on the long bottoms and then
along the contour of the end hoop (again – so the entire greenhouse can be inflated). The process works best with at least
2 people, we could have easily used a third. One person pulls on the plastic to ensure it’s tight and the other person
installs the wiggle wire. (Kelli will tell you the worst job is the hand cramps you get for pulling so hard on something as
slippery as plastic – I might tell you the worst job is mashing your fingertips over and over with the wiggle wire in the
channels… honestly, neither job is horrible - but also not something you look forward to repeating!)

Inflator - go!
With the plastic secured along almost the entire greenhouse, we left the corner where the inflator gets installed un
attached just enough so I could worm my way in-between the 2 layers of plastic and cut a hole through the inner layer. In
this picture you can see the white dot looking thing – that’s the diffuser that the inflator motor blows through. It sites
between the 2 layers of plastic and keeps the space pressurized. One thing I decided to do as an added precaution was to
place a piece of 4″ wide greenhouse tape over the spot where I cut the hole. That should help keep this area for
developing any stress tears over time as the wind punishes the structure.

Yup - it's inflated.
After the inflator fan was installed we finished installing the last of the wiggle wire in that corner and trimmed off the
excess plastic. We then fired up the fan and let the greenhouse puff up. It was an impressive site to see as the wrinkles
all disappeared and the plastic shell became a component of the structural support for the building. Very impressive
design. We have noticed that our blower seems to be a little “over active” and we have ordered a control switch to dial in
the perfect amount of “inflation”.
All in all without a final tally of the receipts the project came in a little more than we thought it would (don’t they all) BUT
the structure is a LOT more substantial than we expected and are pretty optimistic that it will sustain the big winds we get.
Total price tag including all the mistakes and the bender we will have for years : around $1500. So given it’s size, that’s
like $4.46 a square foot of protected, sun warmed space (not to bad) We also learned a TON in doing this, knowledge that
would have been REALLY expensive to acquire on a full fledged kit. Actually – after we finished it we both looked at the
space next to it where the bales of hay sit and discussed how long the next one will be. :) The last thing we have left to
do is attach the last little rolled up plastic that is along the hooped ends to the faces. It’s a small job (just not done).
We also learned several things we would differently next time. Big doors on both ends. Translucent panels on the ends.
Grade the area where it will be constructed first (building this OVER the low tunnel was stupid and caused things to be
much more difficult than they needed to be). Install water hydrant inside the house for easy water access. I’m sure there
will be other lessons learned too – but in the end – we are REALLY, REALLY happy with our homemade greenhouse! (for a
few more pictures visit our Flickr Photostream)
The plants that have been moved inside the new greenhouse seem to like it – but they are not very vocal anyhow… Stay
tuned for a tour of the inside…

Our first homemade greenhouse



Part I Site Planning and Construction
Article

Constructing a Simple PVC High Tunnel
by Jim Hail, Robbins Hail, Katherine Kelly, and Ted Carey

Introduction

This low-cost, 30’ long by 18’ wide high tunnel is constructed using PVC pipe for
hoops. The materials cost roughly $500 (including shade cloth for summer production) LINK:
How to Build
and we didn't shop for the best buy on materials and lumber. A slight disadvantage of a High
the design is that curvature of the hoops may allow rain to run inside the edge of the Tunnel
by Amanda
house when the sides are raised for ventilation. One person can complete most of the Ferguson,
construction, but inserting the hoops and putting on the plastic requires at least two University of
Kentucky
people. Also, it is nice to have someone to share the heavy work of driving in the
ground posts. A crew of four can easily construct a high tunnel of this design in a single
day.

The dimensions of this high tunnel design may be scaled-down if you have limited
space available for your high tunnel. At a lesser diameter, or in well-protected locations,
it may be possible to use 1” PVC for the hoops, with 1½” PVC for the posts. The length
of pipe to use for hoops may be calculated using the formula for the circumference of a LINK:
Hoop House
circle, (3.14)r, where r is half the width of your tunnel. Add 3’ to insert into the ground Construction
posts. for New
Mexico: 12ft
PVC will react with the polyethylene greenhouse covering, so in order to attain the X 40ft Hoop
House
expected 4-year life span of the plastic, measures should be taken to prevent contact
between the PVC and the polyethylene covering. This may be done by painting or
taping the side of the PVC hoops that will be in contact with the plastic. Having said
that, the oldest high tunnel at Bear Creek Farm in Osceola, Missouri, is eight years old
and is still covered by its original plastic, which is in contact with the PVC hoops.
Note: Our procedure calls for driving 3’-long PVC posts into the ground after laying
out the baseboards. We have found this to be a convenient way to proceed. However,
in shallow, tight or stony soils, it may be necessary to dig holes using an augur, and
then set the posts in concrete. If it is likely that you will need to do this, then posts
should be set before laying out the baseboards.

Materials

Material Dimension Quantity Notes
Twine & Pegs For corner and baseboard layout.
For baseboards. The boards will be in contact with
the soil, so you might consider a rot resistant wood,
Lumber 2" x 6" x 10’ 6 such as cedar or redwood. If you will be growing
food crops in the tunnel, it’s probably best not to use
treated lumber because of possible health concerns.
1" x 4" x 10’ 6 For hip boards.
Lumber for attaching baseboards, bracing end hoop,
2” x 4” x 8' 18 and framing end-walls.
Lumber for framing doors. Depending on door size,
2” x 4” x 10' 4 amount of bracing desired amount may vary. We put
a 32”-wide door on each end.
For attaching plastic to hip boards and end-walls.
Poly tape may also be used for attaching plastic to
Furring strips 1" x 2" x 10’ 12 end walls. Wiggle wire is a more costly but
convenient method for attaching plastic to hip
boards.
Schedule 40 1½” x 20’
12 For 11 hoops + purlin.
PVC pipe bell-end
10’ x 1½”
12 For 11 hoops + purlin.
straight-end
3’ pieces of
22 For ground posts. Requires 8 10' pieces
2”
Primer & Glue . . For connecting PVC pipe
For attaching hoops and posts to baseboards, and
Carriage bolts 4½” x ¼” 33 hoops to purlin – purchase bolts, washers and nuts.
Deck screws 1½” 1 lb
2½” 2 lb
3½” 2 lb
Chain link
31' 2 For roll up sides.
fence top rail
PVC fittings 1” . To make handles for roll up sides.
Self-tapping For connecting top rail pieces, and for attaching
. .
screws PVC handle to roll-up side.
For covering the house use 6 mil UV stabilized. For
Greenhouse the end walls, you may use a lighter gauge material,
30’ x 34’ 1
polyethylene since it may be taken off each summer to enhance
ventilation.
White 38% shade cloth with grommets sewn every
Shade cloth 30’ x 25’ 1 3’.

Tools

Step ladder
Level and plumb line
Stapler and staples
Sledge hammer for driving baseboard stakes and PVC ground posts
Saw for cutting lumber and PVC
Drill with screwdriver bit, and with extended ¼” wooden drill bit for drilling holes for
carriage bolts

Site Preparation and Construction

1. Site Preparation. Choose a good site for locating the tunnel with respect to light,
drainage, access, irrigation, etc. Prior to beginning construction you may wish to build a
slightly elevated, level pad, or take other measures to ensure that run-off water will not
flood the high tunnel, particularly in the winter. Orientation with respect to wind is not
critical, but we have oriented ours east west, meaning that prevailing winds are usually
from the sides.

2. High Tunnel Layout. Mark the corners of a rectangular area 18’ wide by 30’ long.
Make corners square by ensuring an equal distance between perpendicular corners
(should be 35’ between outer corners of pegs). Drive 2”x2” peg into the ground at the
corners and stretch twine around the outsides of the corner posts where baseboards
will run. It is not essential for the tunnel to be level, but this certainly helps to make
doors square. To layout a level tunnel, use a level to adjust the height of the string to be
used as a guide for baseboard placement. We have built ours on slight slopes, with the
baseboards following the slope, and hip boards parallel to the baseboards.

3. Set Baseboards. Cut 14 2’ pieces of 2”x4”, and cut points on ends for driving into
the ground. Drive in these stakes for baseboard attachment on the inside of the guide
string, orienting the broad side of the 2”x4” parallel to the string. For the long sides of
the tunnel, posts should be 10’ from each end (where the baseboards will meet) and 6”
from the ends (to allow space for PVC ground posts). Attach the 2”x6”x10’ side
baseboards to the pegs using 3½” screws, starting at one end (snug with the corner
peg). For the end walls, place a peg 10’ from the outer edge of one of the sideboards,
and 6” from each of the corners. Attach the first 2”x6”x10’ (snug against the end of the
sidewall baseboard) and cut the second one to fit.

Figure 1. Baseboards laid-out ready for ground post installation.

4. Drive in Ground Posts. Mark inside of side baseboards at 3’ spacing starting from
the end of the sidewall baseboard. Remove corner pegs and string and drive in PVC
ground posts at corners and at 3’ marks. Posts should go in roughly to the top of the
baseboard, at most. It is possible to damage the PVC by hitting it too hard with the
sledgehammer, or trying to force it through tight or stony soil. To avoid damaging PVC
with the sledgehammer, have a helper hold a length of 2”x4” over the end of the pipe,
and pound on the 2”x4”. The helper should wear gloves to protect against jolts.

Note: Our procedure calls for driving 3' PVC posts into the ground after laying out the
baseboards. However, in shallow, tight or stony soils, it may be necessary to dig hole
using an augur, and then set the posts in concrete. If it is likely that you will need to do
this, then posts should be set before laying out the baseboards.

Figure 2. Ground posts ready to be driven in.

Figure 3. Ground posts damaged during pounding. This can be prevented by pounding on a 2"x4" rather
then directly on the PVC pipe.

5. Hoop Assembly. Assemble 30’ hoops and purlin by gluing together 10’ and 20’ PVC
pipes. Use PVC primer and glue, following instructions for correct use of products.

Figure 4. Hoops being placed in ground posts.

6. Raising Hoops. Erect hoops by inserting one end into a 2” PVC ground post, and
bending the hoop to insert into the ground post opposite on the other side of the tunnel.
Make sure that ends of hoops extend well into the ground posts (at least 12”). After
inserting the posts, make minor adjustments in the height of the hoops (sight along the
top of the hoops from a ladder) so that all are at the same height. Drill through
baseboard and pipes with ¼” wooden drill bit. Attach using carriage bolts, washers and
nuts, pushing the bolt through from the outside, and tightening the hoops snug to the
baseboard

Figure 5. Drilling through baseboard, ground post and hoop. Carriage bolts will hold hoop in place.

7. Purlin Attachment. Attach purlin (30' 1½ PVC pipe) to the inside of the hoops. Drill
through purlin and hoops at 3’ spacing, and attach using carriage bolts, washers and
nuts. Head of the bolt should be up to present a smooth surface to the poly that will
cover the tunnel. We put a piece of duct tape over the top of the carriage bolt before
putting the poly on the hoops.

Figure 6. Tunnel with purlin and hip board in place.

8. Hip Board Attachment. Attach hip boards at 3’ height using 1½” screws. Mark
hoops 3’ above baseboard, and attach 1”x4”x10’s end to end, starting at one end of the
tunnel. Ends of hip boards may be secured together where they meet by screwing a
block of wood across the inside of the junction.

Figure 7. Hip board in place.

9. End wall Construction. Use 2”x4” lumber to frame in end walls. There is no hard
and fast rule for end wall design. However the attached picture shows our general
design consisting of four uprights reinforced by horizontal and diagonal bracing.
Spacing door uprights at a standard distance (32”, 34” or 36”) accommodates standard
door sizes. Cut notches in the uprights to fit the inside of the baseboard or the hoop,
and attach using 2½” or 3½” screws.

Figure 8. Tunnel showing end wall design at K-State Research and Extension Center, Olathe, Kansas.

Figure 9. Tunnel showing end wall design at Full Circle Farm, Kansas City, Kansas.

10. End wall Bracing. Attach end wall bracing. Cut 2”x4” lumber to run from baseboard
close to the second hoop, and attach to end wall and baseboard.

11. Plastic Preparation. Attach furring strips end to end along the upper half to the hip
boards. Alternatively attach the channel for wiggle wire using self tapping screws.

12. Plastic Attachment. It is best to do this on a calm day. Lay out the poly lengthwise
on one side of the high tunnel. If you are cutting from a longer roll of plastic, be sure to
leave 2’ extra on each end to allow for attaching to the end walls. Pull plastic over the
tunnel. A simple way to do this is to secure a rope close to the edge of the poly at each
end of the tunnel by placing an object such as a tennis ball under the plastic and tying
the rope around it through the plastic. Then the rope is thrown over the tunnel and the
plastic pulled over the tunnel using the rope. Make sure the plastic is well centered on
the tunnel and then attach by placing furring strips over the plastic, snug against and
just below the furring strips already attached to the hip board. Attach the furring strips
with 1½” screws, placed every 2 or 3 feet. Pull the plastic tight and attach to the other
side in the same way. Finish securing the plastic by attaching to the end walls using
additional furring strips. Note, you may also use poly tack strips (commercially
available).

Figure 10. Poly attachment to hip board using one furring strip. This method is less secure than others
since poly tends to tear at the screws.

Figure 11. Picture showing the 2-furring strip method of attaching poly to the hip board.

13. Roll-up Side Installation. Attach roll-up sides. Assemble top rail pieces to roll up
sidewall plastic with. Make sure the pipe is longer than the tunnel on both ends so that
you can attach a handle to it, and to avoid difficulties with rolling up sides. Attach the
pipe to the poly. We have used duct tape for this, but a better option is to use special
clips for attaching poly to pipe, which are available from commercial sources. An
alternative is not have roll-up sides at all, but to simply tie up poly when ventilation is
required. This is easily done by placing eye-hooks in the hip board at each hoop, and
running a piece of string below the sidewall poly, around the hoop and back. Both ends
of the string are tied to the eye-hook. For roll-up sides, various options are possible,
figure 8 shows a PVC crank that we have used.

Figure 12. Poly attachment to hip board using wiggle wire.

14. Stabilize Sidewalls. Prevent sidewalls from billowing. To prevent sidewalls from
flapping in the breeze, some sort of support is needed to help keep them in check.
Pieces of used drip tape running from the hip board to the baseboard at each hoop is
effective for us. Using a fender washer along with the screw prevents screws from
tearing though the drip tape in high winds

Figure 13. A drip tape strip from hip board to base board at each hoop can keep side walls from
billowing.

15. Install plastic on the end walls. Since we take off the end wall plastic during the
summer months, we use a lower thickness end wall plastic. Either commercially For more on
suppliers go
available poly tack strip or furring strips may be used to secure a sheet of plastic to: Resources
completely over the end wall. Then a hole may be cut for the doorway.

16. Frame Door. You can make a door, or use an old door on one or both ends of the
tunnel.

17. Shade Cloth Installation. Shade cloth helps keep temperature down during the
summer in high tunnels. In hot years, we put ours on from Memorial Day to Labor Day.
Grommets sewn into the cloth every three feet allow for tying down to eye hooks fixed
into the baseboards. We skew the shade cloth toward the south in order to provide
better shading on that side.

About the Authors
Robbins and Jim Hail own and operate Bear Creek Farm in Osceola, Missouri.

Katherine Kelly owns and operates Full Circle Farm in Kansas City, Kansas.

Katherine Kelly in her newly constructed hoop house.
Ted Carey, Extension Specialist Food Crops, Kansas State Research and Extension
Center Olathe, Kansas.

Building the KSU high tunnel
High tunnels are unheated greenhouses used to extend the growing season. In Kentucky they can
allow year-round vegetable production.
In 2005-06 we erected a 30' x 40' high tunnel at the Kentucky State University research farm,
using a frame salvaged from a heated greenhouse. The following pictures show the construction
process. A table showing the cost of materials is at the bottom of the page.
Click a picture to see a larger view. Click here for a detailed examination of the effect of this
tunnel on microclimate.

September 6,
September 7, 2005
2005

Untreated 2x4s A screen door frame was built to fit inside metal hoops

were painted to salvaged from a used heated greenhouse.

protect the end wall

framing studs.

Organic standards

do not allow treated

wood to come in

contact with the soil

or crop.

September 8,
September 13, 2005
2005

End walls included Metal hoops were screwed to each end wall, then

4' x 4' window aluminum wiggle wire track was attached to the upper

frames. edge of each hoop with metal screws.

September 13,
September 13, 2005
2005

The summer cover Anchors of galvanized steel pipe, welded to angle iron,

crop of cow peas were pounded 2' into the soil to support each end wall.

was incorporated

into the soil at the

construction site.

Cowpeas were

chosen as a heat

tolerant cover crop

that would add

nitrogen and

organic matter to

the soil.

September 13, September 15, 2005

2005

End wall frame Workshop participants at the KSU farm field day attached

struts were bolted interior hoops to anchor pipes. Anchor pipes had been

to the anchor posts. pounded at an angle, with a wooden block between the

pipe and sledge hammmer to prevent the pipe end from

splaying.

September 24,
September 24, 2005
2005

Completed tunnel Frame structural details. Top: End wall struts supported

frame. by angle iron and anchor pipe. Bottom: Pipes joined by

brackets (left) and sleeves (right).

December 7, 2005 December 7, 2005

Recycled plastic 1x6 A 60 W blower fan was attached to a hoop, and through

toe boards were the inner plastic layer. Hoses were attached at the corners

attached around the of the house to allow air to pass between the side walls

house perimeter. A and end walls.

strip of 2x2 ran the

length of the house,

2' above the soil

surface. Aluminum

wiggle wire was

screwed to the end

wall toe boards and

the side wall 2x2.

Two layers of 6 mil

plastic were draped

over the frame, and

attached to the end

hoops with wiggle

wire.

December 7, 2005 December 7, 2005

Two layers of end Attaching plastic to the frame took about three hours on a

wall plastic were calm afternoon.

attached with

wiggle wire

(foreground).

January 18, 2006 January 25, 2006

An 8' wide paving Six-week-old lettuce and kale seedlings were transplanted

stone pad was laid on one-foot centers.

atop gravel and

sand at one end of

the house. An 18"

wide path was

constructed down

the center of the

house. Feather meal

fertilizer (Nature

Safe, 10-2-8) was

incorporated into

the soil with a roto-

tiller at 100 lbs N

per acre, and three

beds were formed

on each side of the

center path.

January 27, 2006 March 2, 2006

Lettuce, beets,
Right bed: Transplanted kale (foreground) and lettuce
radish, and spinach
(background). Left bed: Direct-seeded greens.
were direct-seeded.

March 21, 2006 February 2006 - June 2007

Ready for harvest! Temperatures inside and outside the high tunnel.

Left bed:

Transplanted lettuce

(foreground) and

kale (background).

Right bed: Direct-

seeded greens.

Cost of high tunnel materials

Expected life ¢ per square
Material Cost $ per year
(years) foot per year

Salvaged hoops $1,020 20 $51.00 4.3¢

(estimated value)

Wiggle wire & track $250 20 $12.50 1.0¢

Paving stones $380 20 $19.00 1.6¢

Plastic boards $300 10 $30.00 2.5¢

Screen doors $250 10 $12.50 1.0¢

Lumber $160 10 $16.00 1.3¢

Fasteners $60 10 $6.00 0.5¢

Paint $30 10 $3.00 0.3¢

Fan $100 10 $10.00 0.8¢

Plastic $660 4 $165.00 13.8¢

Total $3,210 $325.00 27.1¢

The plastic accounted for only 20% of the up-front cost, but will account for more than half of
the cost amortized over time. The value of crops harvested should exceed the up-front material
cost in the first year.

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