by Charlene Burgi
This is the time of year when water use for irrigation should be decreasing, but quite the opposite occurs. In fact, September and October are the months when people tend to overwater the most. We think this is the hottest time of year so hydration is critical. But actually, we are imposing our needs and comfort levels onto our plants!
Let’s take a closer look at the science:
- The days grow shorter and the nights are longer after June 22nd
- Evapo-transpiration (ET) begins to drop during July
- Water consumption for plants begins to decrease during July
- Plants prepare for winter dormancy after July
Evapo-transpiration (ET) is the combination of water that is lost through evaporation from the soil and through transpiration from plants (we perspire, plants transpire). This number is the inches of water a week that you need to replace to keep your plants alive.
I went back to our California Irrigation Management Information System (CIMIS) weather data to see what the peak week and water requirements were for plants:
As the table shows, ET—and your plants’ water needs—typically peak around the end of June or beginning of July.
By now, you might be asking what this mean to you. It means this is the time of year we tend to waste water and add unnecessary dollars to our water bill. While you and I need to hydrate more and stay out of the sun when the temperatures reach triple digits, we don’t need to turn up the runtimes on our irrigation systems to compensate for our own discomfort. Just because you’re thirsty doesn’t mean your plants are!
Our plants thrive in a different manner. For example, a few weeks ago I saw my Japanese Anemone flowers drooped over, but I resisted pouring water on them as it was during the heat of the day and I knew water would burn the foliage. By evening, the flowers recovered and were pretty and pert without me adding the water I thought they needed.
To save water in your garden this fall, add mulch to slow down the soil evaporation, turn down the controller’s runtimes by using our Weekly Watering Schedule or purchasing a smart controller, resist pouring water on plants if you see wilting when you know the ground is still holding moisture, and save money in the process!