While watering your lawn an hour a week is a good rule of thumb, other factors can influence how long to water your grass.
Time of Year
Grass may require more watering time during its growing season.
Warm-season grasses, such as centipede and St. Augustine grass, grow best during the summer, when temperatures hover between 80 and 95 degrees Fahrenheit. They could be watered up to two inches a week during the summer.
Cool-season grasses like ryegrass and fescue thrive in the fall and spring in cooler temperatures between 50 and 80 degrees Fahrenheit. You may need to water the lawn more during this time to encourage growth.
Outside of their peak growing season, you don’t need to water your lawn as much or as frequently. That could be as little as 20 minutes every two weeks, depending on the type of grass and its overall water needs.
Type of Soil
If your soil tends to drain quickly and dry out more often, you may have to water your grass longer than an hour a week.
On the other hand, if your soil is slow to drain and you notice standing water or soggy spots, you might water it for less than an hour a week.
Type of Grass
The type of grass your lawn has will also impact watering time. Warm-season grasses are often more hardy and can get by with as little as an inch of water during peak season.
Generally, cool-season grasses need about 20% more water than warm-season grasses to thrive.
Sun Exposure
If the sun shines on your lawn for most of the day, you may need to water it more often as the grass can get dried out due to evaporation. However, if your lawn is shaded or partially shaded during the day, you may find you can go longer between waterings because little moisture is lost to evaporation.
Rainfall
If it’s a particularly rainy season in your area, note the estimated rainfall for the day and subtract that from your lawn’s weekly watering needs. For example, if a 1/4 inch of rain accumulates one day, water your lawn just 3/4 of an inch the rest of the week. To be exact, measure rainfall with a rain gauge.
Age of Grass
Learning how to reseed a lawn? Freshly seeded grass or new sod will need notably more water than an established lawn. A lawn with new seed should be watered ten minutes twice a day. A freshly sodded lawn should be watered twice a day for 20 minutes at a time. Aim to water new grass on this schedule for a few weeks until roots are established.
Watering Method
The method by which you water your lawn can be more or less water efficient.
A classic hose and nozzle will get the job done quickly, but be careful with water pressure, as too much can damage roots or flood the soil. Aim to create a gentle mist or rainshower over the lawn instead of pressure washing the roots. Too much water pressure can drain nutrients from the soil and erode the root system.
A sprinkler system is very efficient with water and may mean you don’t need to water the lawn for long, depending on how much water your system emits. Set a timer to ensure the lawn’s properly hydrated and doesn’t get waterlogged.
A drip irrigation system delivers water straight to the roots of the grass, but it might need to run longer than a hose or sprinkler system because of its slow release of water.
When to Water Your Grass
In addition to understanding how long you should water your grass, it’s important to know when to water it for maximum impact. Watering your grass during the hottest time of day could mean the moisture dries up before it even reaches the roots.
When the weather is 95 degrees Fahrenheit or hotter, it’s important to water your water during the cooler times, especially in the morning or evening, when the lawn isn’t receiving direct sun. That means running the sprinkler system or getting out the hose before 9 a.m. to avoid direct sunlight and high winds, which will allow more moisture to make it to the roots and soil.
An evening watering session should be between 4 p.m. and 6 p.m. If you water later than that, you run the risk of a wet lawn overnight, which can lead to fungal growth and pests. Watering in the early evening gives the grass enough time to dry out and drain before the sun sets and cool temperatures set in.
During the cooler season, the time of day is less important when it comes to watering your lawn. Just keep in mind the lawn shouldn’t be soaking wet when the sun sets.