Smart Irrigation in the Hot Summer Garden

Photo taken by: Tracey Petersen

Throughout the Sierra foothills, July is the month with the highest average rate of evapotranspiration, a measure of how much moisture plants evaporate and “breathe out.” This makes sense when you consider the recent high temperatures we’ve been having.  The Irrigation Association designates July as “Smart Irrigation Month,” with good reason.

Search the Internet for “Smart Irrigation Month” and you will find tools and calculators, resources, smart-phone controllers, brochures and elementary school lessons all designed to educate about water use and to save water and money. Adopting water-savvy habits not only helps reduce water waste, it saves money while promoting healthier lawns and landscapes. Here are some suggestions for wise water use:

Right Plant/Right Place: Add turf and landscape plants that are adapted to the climate and conditions where we live. Tuolumne County Master Gardeners have tested three varieties of buffalo grass in our demonstration garden. Buffalo grass, a North American native prairie shortgrass, has a thin, dark green blade that creates a very attractive turf, but tolerates receiving very little water and fertilizer. If given minimal fertilizer, it needs to be mowed infrequently. For a meadow look, it doesn’t need mowing; for a neater look, it can be mowed once a month.

Mulch, mulch, mulch, mulch: Apply a few inches of mulch to the soil surface around thirsty plants. Mulch cools the soil temperature, reducing evaporation, which allows water to remain in the soil for a longer period of time where plant roots can find it.  Mulch on the surface can reduce water use by up to 50%.

Inspect your irrigation system monthly; adjust sprinkler heads.  Look for leaks, broken sprinkler heads, and misaligned heads. Flush out clogged drip emitters and micro-spray heads. Often water isn’t being applied evenly; although the sprinklers are running, some areas may be getting too little water. Adjust sprinkler heads so that areas that don’t need water—asphalt, sidewalks, streets and roads—aren’t being watered.    “Urban drool is not cool!”

Consider “smart” technology or a rain shutoff switch. There are climate and soil-moisture sensor-based controllers that will evaluate and calculate a watering schedule based on conditions in your microclimate. And rain shutoff switches can be retrofitted to your current irrigation system, thus saving money and water when it rains.

Use low volume drip or micro irrigation. Gardens, trees and shrubs can all be irrigated using drip emitters, micro spray jets or bubblers. Low volume systems irrigate slowly, allowing water to be absorbed by clay soils, minimizing evaporation, runoff and overspray.

Water only when needed. A caller to the Master Gardener office described watering landscape plantings twice a day. All those shrubs and groundcovers were low water users and could probably survive the entire California summer without water.  Learn the kinds of plants in your landscape and their water needs. Water more deeply and let the soil dry between waterings to discourage weed growth, disease and fungus.

One last tip—go to https://ipm.ucanr.edu/, click on “Lawns and Turf” and browse through the “UC Guide to Healthy Lawns” to learn more about irrigating your lawn.

Rebecca Miller-Cripps is a University of California Cooperative Extension Master Gardener of Tuolumne County.