WATERING ESTABLISHED LAWNS
Proper watering practices can improve the quality of your lawn, provide important environmental benefits and conserve water. It may be hard to believe, but most homeowners over-water their lawns!
The average lawn only needs about one inch (2.5 cm) of water per week, either by rainfall or in combination with irrigation. Of course, the water requirements vary between different grass varieties, but one inch per week is sufficient in most cases. Water requirements also vary with seasonal changes, sun, wind and shade factors, soil conditions and the degree of slope within a given area.
The healthiest lawns are produced when they are watered thoroughly at infrequent intervals.
The best times to water your lawn are early morning or early evening, when there is generally less wind and heat. Watering at these times allows for less evaporation into the air, greater penetration into the soil, and less run-off.
One-inch (2.5 cm) of water per week will allowing the water to reach deep into the root system.
It will usually take 10-15 minutes to water your lawn thoroughly. If puddles or run-off occur, turn your sprinkler off for a few minutes to allow water to penetrate into the soil. If your watering system is applying water faster than it can be absorbed by the soil, you will want to adjust the amount of water applied, or the timing of the application, or both.
Let the lawn completely dry out between watering intervals.
Most turf grass can tolerate dryer conditions over a reasonable period of time.
Grass in need of water will have a grey-blue cast to it. On an adequately watered lawn, footprints will completely disappear within minutes. On a lawn in need of water, footprints will still be visible after a half-hour or more suggesting the need for irrigation.
You also can use a soil probe, such as a screwdriver or large spike, to determine how dry your lawn is. If the probe can be pushed into the soil easily, the soil is probably still moist. But if it takes a lot of pressure to push in, the soil is likely too dry. Water only when the probe is difficult to push into the ground or shows that the soil is dry at a depth of 4 to 6 inches (10.16 – 15.24 cm).
Avoid hand sprinkling because it cannot provide uniformity. Each type of sprinkler design has its advantages and disadvantages. Select the type of sprinkler that best fits your needs and budget.
In-ground Irrigation Systems
In-ground irrigation systems require professional installation. They also require routine adjustments and regular maintenance to be efficient.
The greatest mistake made with most in-ground systems is the "set it and forget it" philosophy. This doesn’t account for the changing seasonal water requirements to keep grass health. Look for a system with an automatic rain sensor shutoff and make sure that water stays on the lawn, not on the sidewalk, driveway or on your house.
Above-ground, Hose-end Sprinklers
Above-ground, hose-end sprinklers range in complexity, cost and durability, but are highly portable. They can work well when properly placed on the yard and adequately maintained.
Impulse sprinklers are designed to shoot a stream of water relatively close to the ground to minimize evaporation. They deliver water in a circular pattern. Many are adjustable from full circle to partial circle configurations.
Oscillating sprinklers deliver water in a rectangular pattern. They feature a long, hollow bar, perforated with holes, that moves from side-to-side gently distributing water across the full rectangular area. Some models can be adjusted to restrict the arm movement to water a partial section of the full rectangle.
Most whirling sprinklers feature spinning arms with nozzles at the end. Each nozzle delivers a stream of water across either a circular or square pattern as the arms rotate.
An alternate whirling sprinkler design features spinning fan-like blades that channel water delivered from perforations in the base across a circular or square pattern.
Turret sprinklers feature an assortment of watering patterns that can range from full- to part-circle, to square or rectangular. They give you the flexibility to select the pattern to match the area you wish to irrigate and allow you to irrigate multiple area shapes with one sprinkler.
Spinning sprinklers are available in a variety of nozzle types to deliver water in a gentle mist, rather than a spray. They work well where low water pressure is an issue and to replace hand-watering for syringing.
Traveling sprinklers come in several types, but all will follow the path that you create across the lawn area to be irrigated. They work well for large open spaces. Most can follow curving, as well as straight paths. Most are designed with shutoffs that are automatically activated at the end of the path.
Sprinklers that do not throw the water high into the air are usually more efficient since they prevent wind and heat from evaporating the water. Either inexpensive hose-end sprinklers or in-ground irrigation systems can provide uniform coverage, but they can also be extremely variable and inconsistent in their coverage patterns.
Whichever type of sprinkler design you select, observe your system in action to identify problems.
Check for leaking pipes or hoses, blocked outlets, leaking or missing gaskets, or misaligned sprinkler heads.
Plan on routine maintenance several times during the growing/watering season.
For maximum efficiency of in-ground systems, consider an irrigation audit conducted by a certified landscape irrigation auditor (CLIA).
Verify Water Uniformity
Without uniform coverage, some areas of the lawn may receive too much water while other areas receive too little. This will result in uneven growth across the lawn and can also make the turfgrass more susceptible to weeds, insects or disease.
You can verify watering uniformity with a very simple and inexpensive method that uses only 4 to 6 flat-bottomed, straight-sided cans (tuna fish, cat food, etc.), a ruler and a watch.
Just follow these steps.
Arrange the cans at random distances away from any sprinkler, but all within the area you assume is being covered.
Run the sprinkler for a specific amount of time, or run the water until a specific amount of water is in at least one can.
Measure the amount of water in each can, checking for uniformity. Some minor variation is expected, but a noticeable difference between any two cans must be addressed by replacing or adjusting the sprinkler or relocating the sprinkler placement.
Watering Difficult Areas
Watering difficult areas requires special attention to achieve maximum benefit and a beautiful lawn. For example, sloped lawn areas can be difficult to manage. Depending on the degree of the slope, runoff may occur before the soil is adequately moist.
To conserve water and ensure even irrigation on slopped areas do the following:
Stop watering if runoff begins.
Wait 30 minutes to an hour and then restart watering.
Repeat this process as needed to soak the soil to a depth of 4 to 6 inches (10 – 15 cm).
Some sloping areas may require use of a specialized sprinkler, drip irrigation or a soaker hose. These methods of irrigation apply water slowly over a small area to reduce runoff and allow better water penetration into the soil. These methods also may be used on small areas of the lawn that are next to concrete, pavers, buildings or walkways, or otherwise difficult to irrigate without wasting water.
Watering sufficiently for the grass may over-water some varieties of trees and under-water others. A common solution is to not plant turfgrass under the drip-line of trees, instead using that area for other types of perennial groundcovers or for flower beds or simply covering it with mulch.
It can be difficult to provide adequate water to corners and edges of the lawn and areas next to buildings, which are all exposed to reflected heat. These areas are more vulnerable to drying out and are easily missed by many sprinklers.
In some situations, you may want to lightly water these areas with a garden hose or watering can.
With a little forethought you can maintain a healthy lawn and conserve water at the same time.