The summer heat has arrived right on schedule. We normally see the hottest days and nights of the year in July when plants and trees in our gardens really begin to show signs of extreme heat stress. Approximately 70 percent of household water is used to irrigate landscapes and much of that water is wasted. Efficient watering is key to keeping plants alive during our scorching summers and to continuing to conserve water.
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In Fresno and Clovis, irrigation is on a mandated three-days-a-week schedule which includes sprinklers, drip irrigation and hand watering. That means plants, trees and lawns will have to go without water for two to three really hot days. Even established drought-tolerant plants can suffer heat stress during long hot spells.
Lawn watering times for warm-season lawns such as bermuda grass in July average 85 minutes weekly depending on sprinkler output; cool-season lawns including fescue require on average 113 minutes of weekly irrigation. Divide those minutes by three to set your automatic irrigation timer. Verify that sprinklers are not watering the driveway or the patio. Signs of drought stress in lawns begin with a change to a bluish or duller green color. Footprints will remain visible for several minutes when parched grass blades don’t rebound well.
Deep slow irrigation that thoroughly soaks the soil in root zones to a depth of at least 12 inches is best for trees. Sprinklers usually water only the top 3 to 4 inches of soil, enough for shallow-rooted lawn grasses but not deeply enough for trees and large landscape plants. Use soaker hoses, bubbler attachments or small oscillating sprinklers and let the water run slowly for three to four hours at least once a week, more often in July for citrus trees which should be deep irrigated when the top 3 to 4 inches of soil is dry.
The roots of most summer vegetables and annual flowers lie within the top 6 to 8 inches of soil. Heavy water users like tomatoes and roses need deep irrigation to encourage their root systems to extend deeper into the cooler, moister lower soil depths. Increase the amount of emitters or use bubbler sprinkler heads on plants that you’ve identified as extra thirsty or increase irrigation times in zones that contain thirstier plants.
The soil in container plants gets hotter and dries out much faster than ground soil. Move container plants into shadier sheltered spots in July and find creative ways to water them on non-mandated days-perhaps with water left over from cooking pasta or a water collection bucket in the shower.
Learn how to switch to drip
Converting your conventional sprinkler system to a water-saving drip system is easier than you might think and putting a drip irrigation system into a new landscape is even easier. The Fresno County Master Gardeners group is offering two free classes, “Irrigation for the Home Garden” on Saturday, July 7 and “The Magic of Mulch” July 21, both 9:30-11 a.m. at the Garden of the Sun, 1750 N. Winery Ave. in Fresno.
Walk-ins are welcome or sign up for Adult Education Classes online on the Fresno County Master Gardeners’ website at ucanr.org/sites/mgfresno.
Elinor Teague: firstname.lastname@example.org