1. Colorado Master Gardener Training
Colorado Garden Certificate Training
Cooperative Extension
Colorado State University
#I-04, January 2003
Watering Efficiently Work Sheet
1. Run Time – For the precipitation rates, calculate the run time to apply the given amount of water.
Amount of Water to Apply
Zone Precipitation Rate Run Time (minutes)
(Inches)
32
1 1 ½”/hour 0.8 inch
2 1 ¼”/ hour 0.6 inch
3 ½”/hour 1.0 inch
4 2” hour 0.8 inch
5 ¾”/hour 0.5 inch
6 1 ½”/hour 1.5 inch
2. Since pop-up heads have a precipitation rate of 1 to 2 ½ inches per hour and rotor heads have a
precipitation rate of ¼ to ¾ inches per hour, what heads in question 1 were pop-ups?
3. Observational Method – Calculate the run time for each zone applying 0.7 inch per irrigation.
Amount of Water to Apply
Zone Precipitation Rate Run Time (minutes)
(Inches)
34
1 1 ¼” /hour 0.7 inch
2 2 ¼” / hour 0.7 inch
3
3 /4” /hour 0.7 inch
4 1 ½”/hour 0.7 inch
5 2” /hour 0.7 inch
6 ½” /hour 0.7 inch

2. Historical ET Method
4. Precipitation rate of 1.5”/hour
Watering once a week
April* May June July Aug. Sept. Oct.
Inches of water per
0.9” 1.2” 1.5” 1.5” 1.3” 1.0” 0.6”
Zone week (Historical ET)
Watering days Saturday Saturday Saturday Saturday Saturday Saturday Saturday
Inches
0.9
Precipitation
to apply
1 rate
Run
1.5”/hr 36
time
5. Precipitation rate of 1.5”/hour
Watering twice a week (Thursdays and Saturdays)
April* May June July Aug. Sept. Oct.
Inches of water per
0.9” 1.2” 1.5” 1.5” 1.3” 1.0” 0.6”
Zone week (Historical ET)
Thursday Thursday Thursday Thursday Thursday Thursday Thursday
Watering days Saturday Saturday Saturday Saturday Saturday Saturday Saturday
Inches
0.45
Precipitation
to apply
1 rate
Run
1.5”/hr 18
time
6. For the scenario in questions 4 and 5 above, if 1” is the maximum amount of water to apply per
irrigation (for soil water holding capacity and rooting depth at the site) circle the better irrigation
pattern (i.e., once a week or twice a week) for each month.

3. 7. Precipitation rate of 2”/hour
Water twice a week (Thursday and Saturdays)
Soak and cycle to prevent runoff on a slope at ~1/4 inch per cycle
April* May June July Aug. Sept. Oct.
Inches of water per week
0.9” 1.2” 1.5” 1.5” 1.3” 1.0” 0.6”
Zone (Historical ET)
Thursday Thursday Thursday Thursday Thursday Thursday Thursday
Watering days Saturday Saturday Saturday Saturday Saturday Saturday Saturday
Inches to
0.45 0.55 0.70 0.75 0.65 0.45 0.3
apply per
irrigation
Precipitation Total run
14
time
2 rate
2”/hr Number of
2
cycle
Run time
7
per cycle
8. Based on soil water holding capacity and rooting depth, 1” per irrigation is the optimum to apply.
Schedule is based on applying 1” per irrigation.
April* May June July Aug. Sept. Oct.
Inches of water per
0.9” 1.2” 1.5” 1.5” 1.3” 1.0” 0.6”
Zone week (Historical ET)
Inches of water per
0.13” 0.17” 0.20” 0.21” 0.18” 0.14” 0.09”
day (Historical ET)
Days between 1”
8
irrigation
Inches
1” 1” 1” 1” 1” 1” 1”
Precipitation
to apply
3 rate
Run
3/4”/hr 80 80 80 80 80 80 80
time