It's hot out!
Ah, summer! Long days and mercury pushing 100°F. This is the time of year for ice cold drinks and AC on high. It's also the time of year that can cause the most stress on your lawn. Here in the Rocky Mountain Region the turf species used in lawns are predominantly cool season grasses. This means that when it gets too warm, they struggle.
Indirect heat stress is the most common problem, and will occur when prolonged daytime temperatures reach over 86°F for an extended period of time. While this does not cause immediate plant death, but can cause issues in plant growth patterns and the plant will try and compensate by going into summer dormancy.
Direct heat stress happens with a rapid increase in temperature, and while not as common, can happen in the spring when we have extreme temperature fluctuations from cool and damp to hot and dry within a week.
Symptoms of heat stress include yellowing and reduced growth. A yellow plant is not a dead plant, but it needs water right away! If you allow the plant to completely dehydrate down to the crown and root of the plant, then plant death can occur. Stressed plants are weakened and therefore more prone to disease and weed infestations.
Knowing what kind of grass you have is important. Tall fescues and native species are some of the best grasses for heat tolerance. Where not only do they handle the hotter temps better, but they root deeper and can pull on a deeper water supply in the soil. Did you know Kentucky Bluegrass is predominantly a surface rooting plant?
Treating for heat stress involves a few simple steps.
One be sure to not overapply Nitrogen in your fertilizer routine, it's for this reason we don't recommend fertilizing in the month of July. If you do fertilize, a high phosphorus fertilizer is best.
Set your mower higher, at least 3" in height, and keep those blades sharp.
Keep a regular water schedule, watering early in the morning instead of late at night.
If your grass has yellowed already, apply extra water if you can (understandably many towns and HOAs have watering restrictions) and then be patient while it recovers.