When… Where… How Much
Water is essential to all life — too little water and we die, too much and we drown. The same is true of the grass in our lawns. Water makes up 70% to 80% of the weight of our lawn grasses, and the clippings alone are nearly 90% water. While most people are concerned about not watering their lawns enough, the fact is that more lawns are damaged or destroyed by overwatering.
Newly installed turfgrass sod has very important watering needs. Proper watering immediately after installation will ensure the turf gets established, and it will also have an impact on how well the lawn flourishes in years to come.
When to water new turfgrass sod
Begin watering new turfgrass sod within a half hour after it is laid on the soil. Apply at least 1 inch of water so that the soil beneath the turf is very wet. Ideally, the soil 3 to 4 inches below the surface should be moist.
Watering tip #1
Pull back a corner of the turf and push a screwdriver or other sharp tool into the soil. It should push in easily and have moisture along the first 3 or 4 inches; otherwise you need to apply more water.
Watering tip #2
Make absolutely certain that water is getting to all areas of your new lawn. Corners and edges are easily missed by many sprinklers and are particularly vulnerable to drying out faster than the center of the lawn. Also, areas near buildings dry out faster because of reflected heat and may require more water.
Watering tip #3
Runoff may occur on some soils and sloped areas before the soil is adequately moist. To conserve water and ensure adequate soak-in, turn off the water when runoff begins, wait 30 minutes to an hour, and restart the watering on the same area, repeating the start-and-stop process until proper soil moisture is achieved.
For the next two weeks, keep the below-turf soil surface moist with daily (or more frequent) watering. Especially hot, dry or windy periods will necessitate increased watering amounts and frequency.
Watering tip #4
As the turf starts to knit its new roots into the soil, it will be difficult, impossible and/or harmful to pull back a corner to check beneath the turf (tip #1), but you can still use a sharp tool to check moisture depth by pushing it through the turf and into the soil.
Watering tip #5
Water as early in the morning as possible to take advantage of the start of the grass's normal daily growing cycle, usually lower wind speeds, and considerably less water lost to evaporation.
Watering tip #6
If the temperature approaches 100°F, or high winds are constant for more than half the day, reduce the temperature of the turf surface by lightly sprinkling (syringing) the area. This sprinkling does not replace the need for longer, deeper watering, which becomes ever more critical during adverse weather.
During the rest of the growing season most lawns will grow very well with a maximum total of 1 inch of water per week, coming either from rain or applied water. This amount, properly applied, is all that is required for the health of the grass, provided it is evenly applied and saturates the underlying soil to a depth of 6 or 7 inches.
Watering tip #7
After the grass roots are established, infrequent and deep watering is preferred to frequent and shallow watering, because roots only grow as deep as their most frequently available water supply. Deeply rooted grass has a larger "soil-water bank" to draw moisture from, which helps it survive drought and hot weather that rapidly dries out the upper soil layer.
How to water new sod
Proper watering technique is a critical aspect of lawn watering, equal in importance to when and how much to water. Here are several factors in proper technique.
Avoid hand sprinkling. It cannot provide the necessary uniformity, as most people do not have the patience, time or "eye" to adequately measure what is being applied across larger areas of lawn. The only possible exception is syringing the surface of the grass to cool it, or providing additional water near buildings or other heat-reflecting surfaces.
Understand the advantages of different sprinkler designs. Each type has its advantages and disadvantages, and its proper use will be determined by the type of sprinkler you select.
In-ground systems require professional design and installation, routine adjustment, and regular maintenance to be most effective and efficient. The greatest mistake made with most in-ground sprinklers is the "set it and forget it" philosophy, which fails to account for changing seasonal water requirements — or even lets the system run during a multi-inch rainstorm. Another frequent problem is heads getting out of alignment and watering the sidewalk, street, or house siding rather than the lawn.
Hose-end sprinklers range in complexity, cost and durability, but are highly portable and can provide uniform and consistent coverage when properly placed and adequately maintained.
Sprinklers that do not throw water high into the air are usually more efficient, because prevailing winds are less disruptive of distribution patterns, the potential for evaporation loss is reduced, and trees, shrubs and other plants do not block the pattern (or are very noticeable if they do).
Several times during the growing season, check for blocked outlets, leaking or missing gaskets, and misaligned sprinkler heads, regardless of the sprinkler design. Select sprinklers and systems for uniformity of coverage. Inexpensive hose-end sprinklers and in-ground systems can provide uniform coverage, but they can also be extremely variable and inconsistent.
Verifying watering uniformity is simple and inexpensive: you need only 4 to 6 flat-bottomed, straight-sided cans (tuna, cat food, etc.), a ruler and a watch.
Follow these steps
- Arrange the cans at random distances from the sprinkler, but all within the area you assume is being covered.
- Run the sprinkler for a specific amount of time, say a half-hour, OR run the water until a specific amount is in at least one can, say 0.5 inches.
- Measure the amount of water in each can, checking for uniformity. Some variation is expected, but a difference of 10 percent or more between any two cans must be addressed by replacing or adjusting the sprinkler or relocating the system.
This measuring method should be used across the entire lawn that has an in-ground irrigation system to ensure maximum coverage and uniformity.
Watering difficult areas such as slopes and areas under trees requires special attention to achieve maximum benefit and a beautiful lawn.
For slopes, see watering tip #3.
For areas under and near trees, you need to know the water requirement for the specific trees as well as the grass. Despite having deep "anchor" roots, trees take up moisture and nutrients from the top six inches of soil — the same area as the grass. Trees and turf will compete for water. Watering sufficiently for the grass may over-water some varieties of trees and under-water others. A common solution is to not plant grass under the drip line of trees, but rather use that area for perennial groundcovers, flower beds or mulch beds.
How much water is applied and needed
The amount of water your lawn requires and receives will determine its overall health, beauty and ability to withstand use and drought. Keep in mind that too much water can ruin a lawn just as fast as too little.
One inch per week is the standard water requirement for established lawns; however, this varies between turf species and even among cultivars within a species. Requirements also change with the seasons and with different soil types.
Look at your lawn to determine its water needs. Grass in need of water will have a grey-blue cast rather than a blue-green color. Footprints still visible after a half-hour or more mean the lawn needs water; on a well-watered lawn, footprints disappear within a few minutes. Use a soil probe, such as a screwdriver or large spike, to determine how dry your lawn is. If the probe pushes into the soil easily, it's probably still moist; if it takes lots of pressure, it's time to water.
Verify watering quantities with the same can method described above, noting the time it takes for the cans to collect a specific amount of water. For example, if 0.25 inches collects in 30 minutes, it will take one hour to apply 0.5 inches and two hours to apply 1.0 inch.
Water timers can help provide consistency and can be programmed to turn off when no one is awake or at home. Some timers measure just the amount of time water is flowing, so you have to know or calculate how long to set them. Others measure the number of gallons flowing through. Knowing that 600 gallons per 1,000 square feet equals one inch of water will help you calculate the timer setting your lawn requires.
Article source: TPI (Turfgrass Producers International)
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