Water has become an important issue for many communities, and it is likely the problem will become more acute, especially during periods of little precipitation. In fact, some cities and towns have already imposed restrictions on outdoor water and irrigation use. Even if you don’t live in one of them, trying to conserve water whenever possible is always a good goal. Here are some suggestions for making the most efficient use of your watering practices.
When to irrigate
The purpose of irrigation is to help prevent lawns from suffering from drought stress which can lead to dieback if not properly addressed. Although the amount of rainfall received in New England is generally enough to sustain lawns, it is not uniformly distributed throughout the year. Therefore, it may be necessary to provide supplemental irrigation, especially during the summer months when temperatures are at their highest.
Many variables influence the amount of water used by your lawn, including, sun exposure, temperature, humidity, wind, grass species, root depth and development, and soil texture. Because so many factors impact turfgrass water use, it is difficult to give a general estimate of how often to water a lawn. The best technique for determining when to irrigate is to observe your lawn’s condition and water when needed rather than on a set calendar date. This also helps to avoid irrigating close to rain events that result in wasted water.
Detecting Wilt and Drought Stress
In order to conserve water and avoid overwatering, lawns should be watered just at the onset of “wilting” which is a precursor to drought stress. This may be difficult to determine initially, but a little knowledge and experience will make it manageable. Wilting occurs because the plants’ internal water content drops so low that the plant cannot remain turgid (a fancy scientific word for stiff). Grass undergoes a series of visible changes when they begin to wilt: development of a bluish-green color; the rolling or folding of grass blades; and footprints remain visible on the lawn for several minutes after walking on it. These initial symptoms of wilting will not cause permanent injury to the lawn. However, they do indicate that the lawn should be watered soon in order to avoid drought stress and possible plant death.
Under periods of prolonged drought, cool-season grasses common in New England have the capacity to avoid death by entering into a state of dormancy. Dormant turf appears straw-colored and does not grow, but importantly, it is not dead. When drought conditions cease, the grass is capable of resuming normal growth. Although the lawn will rebound from dormancy, it is much more susceptible to disease, insect injury, and weed invasion. If you cannot tolerate the look of dormant turf or possible repairs later in the season, timely watering is the only way to prevent drought-induced dormancy.
Effective Watering Practices
Frequent lawn watering encourages shallow rooting and may increase the potential for disease or susceptibility to stress injury. Instead, always water deeply and infrequently. While you should set irrigation based on need, a general guideline is that your lawn should get 1 inch of water per week from either rain or irrigation. If you don’t know how much water your irrigation system puts out, place empty cans (tuna or cat food cans work well) throughout your lawn before your system runs and measure the amount of water after a complete cycle. If possible, concentrating watering events in one or two sessions per week ensures that enough water is reaching deep into your lawn’s root zone.
While you can irrigate your lawn at any time, we highly recommend doing so in the early morning (eg. 3-7am). Cooler temperatures at this time ensure minimal evaporation, deep soil penetration, and any excess or pooled water will evaporate off with sunrise preventing prolonged leaf wetness. The notable exception here is when temperatures are extremely high. At these times, an additional short 5-10 minute watering at midday will help cool the lawn down quickly and reduce heat stress on hot summer days.
With these tips, you are ready to keep your lawn hardy and healthy all season long for you, your family, and your pets to enjoy!