After the first two weeks, watering can be cut back so the top inch or so dries out for a day or two before watering. This helps ensure that the soil is getting air. Except in dry climates, good soil for growing grass and ornamental plant roots would be about one-half solids and one-half pore space that is about one-half filled with air. Areas that are watered with frequent small applications tend to have two problems. Down deep, the soil will still be dry, so few roots can grow there. And up top, the soil will be too wet, so few roots will grow there either.
After the first month, the watering should be only an inch of water every week to 10 days, applied in one or two waterings. Water that can soak down deep will allow the roots to grow into a larger volume of soil, thus preventing problems of not enough water for a longer period of time.
Every climate zone across the country has a different amount of rain and evaporation. Plants transpire water off the leaves as a method of moving water and nutrients throughout the plant. The combination of evaporation and transpiration is how water is lost from the soil that has been irrigated. The evapotranspiration rate, as it is known, is the amount of water necessary to add to a lawn to keep the plants healthy. The ET rate will change daily, monthly, and seasonally.
If not enough water is added to a soil to keep up with the ET rate, the plants will not have enough water, and they will suffer. If too much water is added, the extra water will either drain away or run off the surface. At the same time, the pores in the soil will be filled with water, and the plants will suffer by not getting enough air to the roots. Your local extension service can tell you the local ET rate. Professional turf people, such as those maintaining grass in golf courses or athletic fields as well as farmers irrigating fields, have been concerned with the ET rate for many years. Homeowners will have to become familiar with the ET rate as more places run into shortages of water available for landscape watering.
Compare your local ET rate with the actual amount of water used on your lawn, and you can see if you are using too much. Use a rain gauge or tin can to judge how much water has been applied. Use enough to soak a good soil about 8 to 12 inches, which allows the grass roots to fill this space. With this much soil, the established lawn can often go two to three weeks without watering.
The use of automated irrigation controllers has kept many people from knowing how much water their lawn actually needs and how much is actually being applied. Most people are not watering their properties for the best health of the plants or for the lowest water usage. There are several brands of irrigation equipment that now have very accurate sensors that are installed in the soil to monitor the ET rate of the actual lawn they are applying water to. The sensors allow the controllers to actually change the amount of time a specific area of lawn is watered. The plants are not overwatered or underwatered. Using less water is the proper way to water landscapes and will be the way they are irrigated in the future as water conservation becomes more important.
