WATERING the LAWN
by Wes Yohey
According to recent studies, as much as 70 per cent of summer water use can be attributed to outdoor activities. This can create quite a drain on community and well water levels. This article will provide strategies to strengthen your grass’s health while maximizing the water that is available to minimize the effects of extended dry periods and drought.
Drought management begins in the fall and spring seasons. If you wait until summer not only is it too late, but you generally do more harm to the grass.
There are three main types of soil, silty, clay and sand. A fourth type, loam, is a mixture of varying degrees of the three main types. Knowing the predominant soil type in your area affects the amount of water your lawn will need to be most effective.
Loam soil is the most desirable and common in heavy agricultural areas. It has better infiltration and drainage than silty soils, easier to work than clay and has generally more nutrients than sandy soils.
Most grasses prefer at least 1” of water per week. This amount of water will moisten 4-5” of clay soil, 6-8” of loam soil and up to 12” in sandy soil.
The type of grass, or grasses, you have can impact your watering requirements. Some varieties require 25-50% less water than the popular Kentucky bluegrass. Zoysia and tall fescue grasses are two good examples.
The best defense for an extended drought is a long, dense root system. Deeper roots have a greater base from which to pull water and nutrients.
When mowing your lawn, it should never be cut lower than 2½” with clippings limited between 1-1½”. Taller grass produces longer roots, is more resilient to dry spells and reduces the probability of turf scalping, especially during fast growth periods. Maintaining proper blade sharpness, particularly on power rotary machines can greatly reduce turf scalping. Repeated scalping can reduce your lawn's root density.
Compacted soil can also retard root growth. The best way to fix this is with core aeration. Core aeration is the process where 2-4” plugs are cut from the top soil and deposited on top of the lawn. Not only does this relieve soil compaction but it also increases filtration of water and nutrients to the roots and helps reduce thatch.
Spike aerators are available as well, but while this type aerator increases nutrition to the roots, it doesn’t relieve soil compaction.
With either type aerator, only perform this during the spring or fall seasons. This is a pretty invasive operation and performing it during fast growth allows the grass to repair itself quickly and reap the benefits from the aeration. If performed during the summer months, the procedure can actually do more damage.
You can read more on lawn aeration in our Lawn Aerating article.
Water conservation isn’t just a way to save money, it’s also our ecological responsibility. And there are many ways to minimize your lawns watering requirements.
The first step is easy, let your lawn grow and green naturally through the spring. Small dry spells during this time actually promote deeper root growth. It should be late spring or early summer before your grass may need some help.
Grass will display stress signs when starting to suffer from lack of water. Most grasses will start to wilt and turn a bluish-gray color. You’ll also see evidence of “footprinting” where the grass doesn’t bounce right back up when stepped on. (If dry conditions continue, the grass will employ a survival technique of dormancy when it starts to turn brown. At a minimum, grasses need at least an inch every 2-3 weeks to prevent complete turf loss. While the grass may not green up, it should be a sufficient amount of water to maintain the lower half of the plant and increasing the recovery time when rain becomes more available.)
If a rain is due in the next day or two, it won’t hurt to wait, otherwise, when a third to half your lawn is showing these drought symptoms, it’s time to water.
How much water does the grass actually need?
When watering your lawn, the goal is a long enough watering to penetrate the soil to the extent of the roots. Too much and we’re wasting water, too little and we’re not encouraging root growth (in fact, repeated small waterings promotes weed growth). The first thing we need to establish is the root depth. As stated earlier, grasses generally need an inch of water per week. But a more effective and exact method is available.
Push a shovel blade fully in the ground (after contacting your utility company to mark incoming lines and pipes) and push and pull the shovel handle forward and back horizontal to the ground to create a few inches of separation in the soil.
Create enough separation to enable you to see the depth of your grass roots. Take a measurement of this depth. You may want to check a couple different areas, for instance, traffic areas, under trees, etc.
The second variable we need is how far the water soaks into the soil.
If, after a few days of dry weather, you are ready to water your lawn, place a container on the lawn so it catches some water. We want to measure how much water is output by the sprinkler. Second, record the amount of time you run the sprinkler, for this first exercise, we suggest 15 minutes.
Assuming it hasn’t rained, the next day, create another slit in the ground with your shovel as described above and see how deep the water penetrated. If the water level extends past the roots, we’ve watered too much. If the water reached down to half the root level, we need to water twice as much, etc.
Alternately, water probes are available to measure moisture depth.
Just as knowing how your soil will respond to certain water levels, how you water your lawn can affect your water usage.
Many experts recommend watering your lawn in the morning as best for the lawn. It’s also better for efficient water use. Between 4 and 9AM, the air is usually at its coolest and calmest so less water evaporates.
While water runoff is usually attributed to drive and walkways, your lawn can also produce runoff. Besides less absorbent soils, thatch buildup in the grass can also affect absorbency. Check your lawn while watering, if you notice puddles building up, shut the water off for 10-20 minutes and allow the water to soak in before proceeding (if it is a thatch issue, wait until fall to correct with power raking or you could damage your lawn).
Some parts of your lawn may require a little more water than others, for instance, common walk paths, unshaded areas and under trees. Water these areas either by hand or with a different style sprinkler.
A properly installed rain barrel is a great way to conserve water. A rain barrel collects water from your home’s downspouts into a large barrel. A typical outdoor water spigot is attached at the bottom of the barrel that accepts standard hose and sprinkler attachments.
Share your lawn watering experience or if you'd like more information.