Heat Stress in Lawns
Much like any other living organism, lawns can suffer symptoms of heat stress.
Heat Stress is caused by high heat and lack of rainfall. This can particularly be a problem in the Colorado environment because of our typically dry summers and lack of humidity. Watering consistently is one of the most important maintenance practices in taking care of your lawn. However, even adequate water is not always enough. Temperatures of well over ninety degrees day after day causes a slowdown in grass growth. With low humidity, the blades of grass can experience a daytime wilt which can cause a loss of color normally associated with a healthy lawn. This does not mean the lawn is dying or in serious trouble.
Eighty percent of a grass plant is comprised of water. High heat and low humidity takes some of this away, even with good watering practices. Lawns that are getting properly watered now will recover much more quickly than a drought stressed yard will when the longer nights and cooler days return.
Water at least 2 to 2 1/2 inches per week. One inch of water should re-wet the soil about 6 inches deep. To determine how much water has been applied, set a straight-sided can under the sprinkler.
Of course, without adequate water, heat stress quickly turns into drought stress.
In a drought stressed lawn, grass soon turns brown and becomes dormant. An early clue to drought stress is when grassy areas show a dark bluish-green cast. Begin applying water when the soil starts to dry out and before the grass wilts and has a chance to become brown.
A word of caution about limited watering:
A single watering during a high heat and/or drought period is likely to do more harm than good. If the grass cannot be kept actively growing with sufficient water, it is best to let the grass go dormant. Inconsistent or “light” watering during extended dry periods will slow the rate of recovery when adequate rainfall does occur. Bluegrass is very resilient and will come out of the heat and drought quickly as long as it is properly cared for and steps are taken to keep insects and weeds out of the stressed or dormant areas of the lawn.
Some things you can do when water restrictions prevent you from watering as much as the lawn really needs:
- Water only that part of the lawn where improvement is most important.
- Water only in the early morning.
- Use a sharp mower blade; the cleaner the cut the less water the grass blades will lose out of the injury done by the cutting.
- Mow regularly until growth slows, but at a higher (rather than lower) cutting height.
- Make each watering consistent and make sure enough water is being applied to moisten soil to a good depth. Remember, with humidity as low as Colorado’s tends to be, a ten minute watering of most sprinkler systems will not likely get enough water into the soil. This will force the roots to go shallow and weaken the lawn’s resistance to heat stress and drought stress/damage
We can help you manage your heat stressed lawn, click here to send us an estimate request, or call us at 303.232.0666.