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HOW MUCH WATER DOES YOUR LAWN NEED???
During the hottest months (June through September), you may need to add an inch and a half to two inches of water to your lawn each week, divided into two or three applications. Apply less water during spring and fall, perhaps one-half inch to one inch per week. There is no need to water your lawn during a typical rainy winter here. Irrigate once every other week if no rain falls during the winter.
DO NOT WATER YOUR LAWN EVERY DAY!
This practice can lead to serious lawn problems, such as shallow lawn roots (making the lawn more susceptible to drought and insect damage), fungal growths and diseases.
To determine how much water your sprinklers are putting out:
Position 6 to 10 flat-bottomed, same sized containers around your lawn. Use drinking glasses, Tupperware, tuna fish or cat food cans; containers with taller sides will keep the water from splashing out. Put some in the greenest areas; put some in the areas that are struggling.
Turn on your sprinklers for 30 minutes. Then, measure the amount of water in each container. There should not be more than a quarter-inch difference among all the containers. If there is, readjust or add to your sprinklers to hit those areas that aren't getting as much water. If, on average, you are getting a half-inch of water per container during that 30 minute test, then you need to water your lawn for two hours a week in the summer, to put two inches of water on your lawn. In this example, you would water your lawn twice a week, for an hour each time.
You may need to adjust this timing if you see water streaming off the lawn. In that case, reduce the amount of time the sprinklers are on at any one time. Then, add a second cycle a few hours later.
It is best to water with rising temperatures, which in the summer, is from about 4 a.m. to 10 a.m. Earlier is better.
HOW MUCH WATER DOES YOUR GARDEN NEED???
Improper watering is the number one cause of plant failure. Knowing how wet the soil is where the plant roots are hard at work can help you determine your plants' health. Keep in mind: different plants have different watering needs. Learn those needs, then group plants together with similar watering requirements. The Sunset Western Garden Book is a good source for that information.
To determine the amount of water at the root level:
A day or two after watering, dig down 8 to 10 inches with a trowel or small shovel, near the drip line (outer canopy) of the plant. Doing this in two or three spots would be more helpful.
At that depth, grab a handful of the soil. Squeeze that handful. If it is muddy and watery, reduce your watering for plants that require regular (but not frequent) irrigation. If it is so dry you cannot form a clod in your hand (it turns to dust instead), increase your watering (for those plants that require moderate amounts of water).
If you can form a dirt clod in your hand, yet break it apart with a little effort, that is probably the correct soil moisture for your plant.
An easier, but more unreliable way to measure the water content of the soil: purchase an inexpensive (under $10) moisture meter. Test it's accuracy by putting its probe into a glass of water. If the probe does not read "wet", choose another. Expect it to function for only a year or so.
Extended, infrequent, slowly applied irrigation is the most efficient watering method. Soaker hoses or drip irrigation systems work best. Here in the Central Valley, foothills, and Bay Area, run them for 3 to 6 hours at a time, twice a week, in the summer. This is only a guideline to get you started. Adjust that timing to your particular soil type and plants.
And, don't forget: add more drip emitters and drip lines as the plant grows, especially for trees and shrubs. Make sure to get water to the outer canopy of the plant (and beyond) where the roots travel.
Listen to "Farmer Fred" Hoffman on The KFBK Garden Show on Newstalk 1530/KFBK Sundays, 8:30-10 a.m.; and, Get Growing also on Sundays, 10 a.m.-Noon, on Talk650/KSTE.
Outside the Sacramento area? Listen to the shows or download the podcasts of the shows on the websites: KFBK.com and KSTE.com