Here is Lesson No. 9 in our "Learn about Lawns" Series.
Many people are not sure when to water their lawn. But don't wait until it turns brown. Inadequate watering puts your lawn under severe stress, which increases its susceptibility to insects and disease. Instead, develop a regimen for regular watering.
Water before the heat of the day, in the morning, even before sunrise. Watering early gives the water a chance to soak in rather than evaporating away. Plus, if there is some excess water that cannot be absorbed, it will have a chance to evaporate. Watering in the evening allows the water to soak in, but excess water will not evaporate and will foster fungal damage.
It is important to water deeply to encourage deep root growth. Light watering results in roots that stay near the surface, because that is where the water is. The shallow ground dries out quickly and so the lawn will need more frequent watering. The deeper soil remains moist longer and so the lawn is less likely to suffer during a drought. Shallow roots are also considered to be a likely cause of thatch. The soil should be moist about 3 to 4 inches deep.
Avoid over-watering; more people over-water than under-water. You may be one of the people who feel that if a little water is good, then a lot of water is even better. That is not true. The objective is to provide enough water so that the lawn does not thirst. Too much water can carry away nutrients, foster fungal spores and disease and stress the lawn.
Most lawns require one to two inches of water a week. The best way to water, especially to conserve water or if the lawn is on a slope, is to water for 5 minutes on and 15 minutes off, until the desired amount of water is delivered. This gives the water a chance to soak in and reduces runoff.
To determine if you are delivering the proper amount of water, place a few cans around on the lawn to catch the water. Use something that has straight sides so you get an accurate measurement. Tall cans can deflect water, so it is best to use short cans like tuna or cat food cans. Measure the water in the cans and multiply by the number of times a week you water. The result is the number of inches of water being delivered every week. Each can should yield about one to two inches per week depending on temperature, shade and type of grass. Sunny and warm locations will need more water. Remember to include any water from rain in your calculations.
To recap, the best way to water is in the morning, two to four times a week, in short intervals but enough to thoroughly soak the ground. A sprinkler system is the best way to deliver the water because it consistently covers the entire lawn and it can be programmed to deliver the water when and as frequently as needed.