The Watering Index (%) is a simple way to represent and understand plant water needs. It is based on weather conditions, such as: solar radiation, temperature, relative humidity, wind, and other factors. Summer represents 100% of maximum water needed for plants.
Use the chart below, along with site conditions, to find the right watering index value for your yard! Maximize water savings by using the Green Drought Value as a starting point and go up from there.
Many new(er) sprinkler timers have a seasonal adjust option (or % adjust) that you can use. To do so, first program your sprinkler times for summer conditions (100% seasonal adjustment factor). You can then just use the seasonal adjust feature to adjust the watering index to the appropriate percentage. For example, if it’s October, you use a watering index of 50-60% and your sprinkler runtimes will automatically be cut by about half based on your summer (100%) schedule.