Knowing how long to water your lawn is important for several reasons. Too much or too little water can result in a mediocre appearance with dead or dried patches that invite weeds. Overwatering can also raise your water bill significantly so it pays to have a fairly close idea of how much water your lawn requires to maintain green, good health. There are several factors to consider when deciding how often and when to water your lawn, including your soil and when the sun is most harsh in your specific hardiness zone.
How Much Water Your Lawn Needs
As a general rule, lawn grass needs about 1 inch of water per week. This figure may change, though, depending on your soil type. Proper drainage goes hand-in-hand with meeting the water requirement of a lawn. To achieve proper drainage, a balance must be struck:
- If the composition of your soil is too sandy, water will run right through it as if it were a sieve. So giving your lawn 1 inch of water per week if it is growing in this kind of soil will not keep it adequately irrigated.
- But if your soil type has too much clay, it will retain too much water. Grassroots do not like to sit in water constantly. Diseases can result from this condition.
A loamy soil strikes the ideal balance for achieving proper drainage. It has sufficient organic matter for the right amount of water retention, and will not lead to waterlogged conditions.
How Long to Water Your Lawn
The important question for lawn health is not so much how long to water your lawn at any given time as it is how much water to give your lawn.
To answer the question, it will take your sprinklers about one hour to put out the required 1 inch of water per week. Establishing a good irrigation schedule will help you achieve your lawn's water requirements.
A related question is how often to water your lawn. You do not have to provide the required 1 inch per week all at once. Instead, you can water for 30 minutes twice a week. But some experts advise against extending irrigation sessions beyond that (for example, watering for 20 minutes three different times a week). Watering too frequently keeps roots too close to the surface. Less frequent watering encourages them to reach down deeper in search of water. A deeper root system is less susceptible to heat stress and pest damage.
The type of sprinkler you use affects exactly how long it will take you to water your lawn, so, again, be prepared to adjust your irrigation schedule accordingly. It will take slightly longer with the type of oscillating sprinkler that you attach to a garden hose because you have to move it around (on large lawns) to irrigate every portion of the lawn. It will take less time if you have an automatic irrigation system because such a system is designed to cover the whole lawn all at once.
Knowing When to Water Your Lawn
The best time of day to water is early morning. When the sun is low in the sky, there will be less evaporation, giving the water a chance to seep down into the root zone. The grass blades will have all day to dry out before nightfall. The longer grass blades stay wet, the greater the chance they can succumb to fungal diseases.
Artificial irrigation should be used only to supplement rainfall. Do not water your lawn if rain is coming, it is currently raining, or it has just rained.
You will not have to supply the same amount of artificial irrigation year-round. Grass needs that 1 inch of water per week when the weather is hot, and/or the grass is actively growing.
Water Schedule for Cool vs. Warm-Season Grasses
A cool-season grass in the Northeast needs to be watered most in late spring, in summer, and in early fall, sometimes as much as three times a week in warmer weather. Continue to water throughout fall but reduce the frequency, since your grass will largely be deprived of water during the winter.
Most warm-season grasses, such as Bermudagrass, are drought-tolerant and they love the heat, which means they can survive on little water during the peak growing season. Warm-season grasses require deeper and more infrequent watering (once or twice a week) than cool-season grasses. Warm-season grasses fare best when watered in the early morning before the sun becomes too hot.
Signs Your Lawn Is Being Over-Watered or Under-Watered
Over-watering is just as detrimental to the health of your lawn as under-watering. Some issues may be caused by either extreme so it might be necessary to look at several problem areas in your lawn to determine if the grass is too wet or too dry.
Signs of Under-Watering
- The grass turns yellow.
- The grass is limp. When you walk on the grass, it fails to bounce back up afterward.
Signs of Over-Watering
- The grass turns yellow.
- Bare spots develop in the lawn.
- Mushrooms are growing on the lawn.
- The turf has a spongey feel when you tread upon it.
- There is visible runoff.
The UC Guide to Healthy Lawns. Agriculture and Natural Resources, University of California.