Watering Grass: A Comprehensive Guide to Watering Your Lawn

By Karon Warren

When it comes to watering grass, many homeowners just set out a sprinkler, turn it on and let it run for a while, assuming they are doing right by their lawns.

The reality is many may be underwatering or overwatering their grass, which can do more harm than good. To help you provide the proper hydration for your lawn, it’s important to water your grass at the right time and in the right amount.

---

Grass Types and Irrigation Timing

Knowing the type of grass you have can dictate how often you should water your lawn.

Cool-season grasses

Types: Bentgrass, bluegrasses, fescues, ryegrasses
Growing pattern: Grow most actively in the spring and fall. They go dormant–stop growing–during the summer, and then again in the winter.
General watering advice: They need water only every three weeks or so if there’s been no rain. If you water more frequently, you could be watering weeds instead of grass.

Warm-season grasses

Types: Bahiagrass, Bermudagrass, Buffalograss, Carpetgrass, Centipedegrass, St. Augustinegrass, Zoysiagrass
Growing pattern: Grow most actively in the summer heat, go dormant in the chill of the fall or winter.
General watering advice: Some warm-season grasses, including Bermuda, Bahia and Zoysia, are among the most drought-tolerant turfgrass species. However, they still require regular watering to maintain a healthy root system, particularly during their midyear high-growth season.

General Lawn Irrigation Advice

Water when the grass needs it.
Most lawns require irrigation once every four to eight days to stay healthy, according to the Natural Resources Conservation Service, a division of the U.S. Department of Agriculture. In fact, the NRCS says irrigating less often and applying more water when you do irrigate results in deeper rooted plants and healthier turf.

Keep an eye on the sky. When it rains for several days, water less. Successive hot, dry days mean water more. If you’re not sure if your lawn needs water, the NRCS recommends this test: If grass doesn’t spring back after being stepped on, it’s probably time to irrigate.

Early morning watering is best.
Early watering gives the grass time to absorb the water, sending it down into the roots and into the grass plants themselves. That plumps up the grass blades with water, allowing them to better endure the heat of the day. Avoid watering during the middle of the day when water evaporates quickly. Also avoid watering on a windy day, which will dry up the water before it can be absorbed by the grass.

Although not as good as early morning, late afternoon also can be a good time for watering grass. You should not water in the evening, though, as lingering moisture can lead to fungal diseases in the grass.

During fall, as part of your regular lawn care maintenance, you should prepare your lawn for the coming winter. Per the NRCS, water through mid-September and then again in mid-October to store moisture in the soil.

Quantity is crucial

When watering grass, it’s important you don’t water too little or too much. Like Goldilocks’ porridge, you want it to be “just right.” Your goal is to moisten the soil deeply. Four inches is good, 6 inches is better. To do so, you need to apply approximately 1 inch of water if you have clay-based soil. If your soil is sandy, reduce this amount to 1/2 inch of water.

Grass Watering for Different Soil Types

Measure Your Water Use

To help you determine when you’ve applied 1 inch of water, put out some straight-sided containers around your yard. Tuna cans work well. Turn on a timer and turn on your watering system. Monitor them, and when they are filled with 1 inch of water, turn off the water. Be sure to time how long it takes to fill the containers so you’ll know how long to leave the sprinkler on each time you are watering grass. See “Keep Your Grass Healthy With a Lawn Sprinkler Audit” for more details.

As part of your lawn care routine, check regularly for signs of overwatering. After watering, walk along your lawn and look for pools of water. This is runoff — water that exceeds the amount that can be absorbed, given the volume of water and the period of watering. The effects of runoff are not good. Runoff washes away fertilizer and newly sown seed, which negatively affects your lawn, your wallet and the environment.

If you experience runoff within the time frame you determined would deliver 1 inch of water to your lawn, divide that time in half (say 15 minutes instead of 30). Water your lawn in two equal segments, allowing time in between for the grass to absorb the water.

Overwatering also can discourage root growth in grass, which, in turn, will weaken the turf, making it more susceptible to tough environmental conditions, disease and daily use, such as foot traffic, children playing and pets running around.

Don’t Panic — Your Lawn May Just Be Dormant

During summer’s hottest days, your lawn may take on a tan or brown appearance, making it look dead. However, many Northern cool-season grasses go through a dormant period not only in winter months but also in summer months. Essentially, the grass is taking a break from growing. If your lawn is in a dormant period, it will start to green up as temperatures cool off and after receiving several days of rain.

Some species of grass are quicker to perk back up than others. Kentucky bluegrass, for example, takes just three or four days to wake up.

In the event your lawn does not revive under these circumstances, it likely is too damaged to recover and will need extensive care to repair, and possibly replace, the existing grass.

Water Sensing Tools

As part of your lawn care, there are a variety of tools and automatic systems to help you in watering grass.

One of the simplest tools is a long-bladed screwdriver. If you cannot insert the screwdriver into your soil, the soil is extremely dry, and the grass should be watered. On the contrary, if the screwdriver slides into the soil with ease, the grass is hydrated and doesn’t need water.

Fancier — though still inexpensive — substitutes for the screwdriver are digital water sensor tools that can be found at any garden store. They have long spikes that you insert into the soil, and give you a readout of how moist the conditions are.

At the high end are underground sensor systems tied in with automatic sprinklers.

Types of Sprinkler Systems

Fixed sprinkler
The fixed sprinkler is simple and economical. It is a metal or plastic vessel with small holes in it that fits at the hose end. The pressure of the water forced through the small holes sprays the lawn. The pattern of spray is determined by the pattern of holes, the volume is controlled at the faucet. To change the area of coverage, you drag it around the lawn.

Gear drive sprinkler
This type of heavy-duty sprinkler is often found on golf courses or other large areas of grass where both large volume and precision in watering is needed. Their gear-driven motion usually has multiple flow controls that let you adjust the distance the water is sprayed, and the angle and force of the spray.

Hose-end spray nozzles
These simple devices are a best seller. Inexpensive and versatile, they can be made of plastic or brass, and are often controlled by a handle that turns the water on and off. The volume and pattern of spray is controlled by either twisting the nozzle or via a dial attached to the nozzle.

Impact sprinkler
With an impact (sometimes called impulse or pulsating) sprinkler, the spraying nozzle is rotated by the pressure of the water from the hose. Made in both plastic and brass; the brass impact sprinkler is more expensive but more durable. Some models are attached to the ground via a spike, others are elevated to become a tripod sprinkler.

Control collars limit the travel of the head, and a rocking arm repeatedly inserts itself into the stream of water to both drive the head and create an additional spray stream. The pulsating sprinkler was invented in 1933 and marketed under the Rain Bird brand name.

In-ground water sprinkler

In-ground water and garden sprinkler systems use a series of sprinkler heads installed at fixed locations in the yard. When properly maintained, in-ground systems give complete and efficient coverage. The most common type is constructed of a network of interconnected PVC pipes installed in trenches dug in the lawn. There are many different types of sprinkler heads to serve various needs. Some spray 360 degrees, some just 180 or 90 degrees for edges and corners. Some heads pop up and then recede to ground level. Ideally, your in-ground sprinkler system should be designed with “hydrozone separation” in mind. That is the concept of grouping plants together that have the same water consumption habits. Your grass would be on one zone, your thirsty ornamental plants on a second and drought-resistant plants on a third. That way you can adjust your spray time and pattern so that all the plants in the zone are happy.

Oscillating sprinkler
At its simplest, the oscillating sprinkler has a metal or plastic bar with holes drilled in it. Water comes out the holes as the bar rocks back and forth and sprinkles the lawn with a gentle spray. You control the size of the area at the source, by adjusting the water volume at the faucet. Great for relatively small, rectangular yards.

More-advanced models such as the turbo oscillating sprinkler allow greater control of the watering pattern and spray volume.

Traveling sprinkler
As its name implies, traveling sprinklers have wheels that let them move through the yard, dragging the hose behind them. Excellent for irregularly shaped lawns.

Other irrigation equipment to consider

Flow control meter
This device is installed between the faucet and your hose, and monitor the amount of water that goes through. Some feature an automatic shutoff control that prevents wasteful overwatering.

Automatic timer

An automatic timer shuts off the water at a designated time. Some models are hose-end, others are built into in-ground sprinkler systems to control the timing of each section of the irrigation system.

Smart irrigation controller
Your phone is now smart. Watches, thermostats and doors, too. So it's no surprise that sprinkler controllers have climbed onto the smart bandwagon. Instead of relying on a fixed timer, they use either Wifi or GSM cellular connectivity to pick up plant data and weather forecasts.

A smart controller will water grass according to environmental conditions such as evapotranspiration (water consumed by grass) rate and amount of soil moisture. In addition, make sure the system includes a shut-off switch that cuts off the sprinklers while it’s raining.

To keep them working effectively, automatic irrigation systems should be inspected and audited every two to three years by an expert to ensure it’s working properly and delivering the right amount of water to your lawn.

Basic Lawn Care Makes Watering Easier

Good lawn care practices produce a healthy lawn which needs less water, and retains what you give it.

Proper mowing height: Keeping grass to the proper mowing height for your grass species will promote deep roots and drought-resistant lawns. Taller grass also helps reduce evaporation. In addition, newly cut grass blades lose water quickly.

Leave the clippings: To help retain moisture in your lawn, do not remove grass clippings after mowing the grass. These act as a natural mulch that serves two purposes. First, mulch is a natural fertilizer, returning valuable nutrients to the grass. Second, during the period it takes for the grass clippings to break down and return to the soil, it will serve as a barrier that slows evaporation, preventing the roots from drying out too fast.

Fertilize when called for: Also, as part of your lawn care routine, properly fertilizing grass can promote deep roots and drought tolerance.

Grass varieties will vary in their fertilizer needs, but in general:
Cool-season grasses: Fertilize at least twice, in spring and fall.
Warm-season grasses: Fertilize every 4-8 weeks during the active midyear growing season.

However, don’t apply fertilizer when the lawn is dry because it will further draw moisture from the grass.

Aerate: To help lawns breathe and drink in water and nutrients, aerate it–remove cores of soil – regularly each year. For cool-season grasses, the best time to aerate is in the fall or spring. For warm-season grasses, the best time is in early summer.

If necessary, dethatch: Over time, your lawn will collect bits and pieces of grass and leaf debris into an interwoven mass called thatch, which can build up on your grass. A certain amount of thatch is both inevitable and beneficial for lawns. It gives a shady space for beneficial insects, holds moisture and is the place where clippings and other organic material break down and return valuable nutrients to the soil.

However, if it collects and doesn’t seem to be breaking down, it can form a barrier, preventing water and air from reaching the root system. When that happens, it should be removed to help promote a healthy lawn.

When doing so, the University of Missouri Extension recommends limiting thatch removal to early spring or fall. If you power rake lawns in late spring or summer, they will require excessive irrigation to remain alive.

Properly watering grass is one of the crucial components in maintaining a healthy lawn. By implementing a good watering and lawn care routine, you’ll have a gorgeous lawn you can enjoy year-round.

Freelance writer Karon Warren’s work has been seen in USA Today, USA Today 10 Best, Curbed Atlanta, Apartment Therapy, and Best Self Magazine. She also is a member of the American Society of Journalists and Authors and Society of American Travel Writers. Her porch has the best container garden on the block.