Watering Lawns

By Mary Bernard, Master Gardener


The key to watering lawns is to apply water infrequently, but thoroughly.  A lawn should be watered when the soil begins to dry out, but before the grass actually wilts.  At the wilting stage, areas of the lawn begin to change color, displaying a blue-green or a smoky tinge.  Loss of resilience can be observed when footprints on the lawn remain visible rather than bouncing right back.  The lawn should be watered before these signs of wilting are obvious.

Lawns can use one and a half inches of water per week in the summer.  A light sprinkling of the turf surface is actually more harmful than not watering at all, because it encourages root development near the soil surface.  Shallow root systems require frequent watering to keep the surface wet, which creates an ideal environment for weeds and diseases.  Encourage deep root growth by infrequent heavy irrigation.

Much of the water applied to lawns is lost to run-off and evaporation.  Monitor soil moisture and adjust irrigation schedule according to seasonal need.  Avoid runoff and puddling as much as possible by cycling irrigations.

Other steps you can take to keep your lawn looking its best and save water, whether in a drought or not, are:

·         Water early in the day - 2am to 8am is best.  Evaporation is minimal, making water use efficiency optimal.  Early evening or night watering is not recommended because wet blades and thatch are highly susceptible to disease development during the cooler nights.

·         Water your lawn separately from trees, shrubs, and ground covers, if possible.

·         Make the necessary repairs to your sprinkler system.

·         Fertilize moderately, applying the low-end amount of recommended rates.

·         Control weeds.  They compete for water, light, and nutrients.

·         Keep your lawn at the correct mowing height.  (Tall fescue 1.5 to 3", Perennial Ryegrass and Kentucky Bluegrass 1.5 to 2.5", Bermuda grass 0.5 to 1.0" )

University of California Cooperative Extension Master Gardener Volunteers can provide additional gardening information upon request.  Call the San Luis Obispo office at 781-5939 on Mondays and Thursdays from 1 to 5 PM.  You may also call the Paso Robles office at 237-3100 on Wednesdays from 8 AM to 12 PM.