Arrow-right Camera
The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Gardening: How to help our heat-stressed lawns

By Pat Munts For The Spokesman-Review

This historic heat means we are going to have to change our lawn maintenance practices until it cools down into the low 90-degree temperatures. We are breaking records all over the region and the humidity levels are headed in the opposite direction fast. All this means our lawns are being stressed.

First, to tell if your lawn is drought stressed, look across your lawn in the sun. If the grass has taken on a blue-green color instead of a warm green, it is water stressed. To confirm this, walk across the grass. If you leave footprints and the surface feels firm, then it’s time to change your watering schedule.

Determining how long to water your lawn in a drought and a heat wave will depend on your type of soil. Water sinks through sandy soils faster than through loam or clay. Loam and clay hold more water and for longer. In general, sandy soil will need more frequent waterings than loam or clay. Under normal conditions, most lawn experts recommend applying at least 1 inch of water each week and to apply it so that it can soak about 6 inches into the soil each time you water. In this hot weather, put down 1.5 to 2 inches a week until we get back into the low 90s.

Sprinkler run times should normally be set at about 30 minutes three to four times a week. Under our current conditions, it should be bumped to 45 minutes at every run at the same day schedule. Yes, your water bill will go up but compare that to the cost of rehabbing a lawn. That said, bluegrass lawns are going to need more water than turf type fescue or rye lawns. All our grasses tend to go dormant in the heat of summer, so some browning is to be expected.

Water in the late evening, overnight or before 10 in the morning. Our humidity here is usually under 20% when it’s hot, so we don’t see the diseases and fungal issues, people in other parts of the country have to deal with.

Do not fertilize heat-stressed lawns. They can’t use the fertilizer when they are stressed, so you are wasting your money. The old rule of thumb that said to fertilize lawns at all the major spring and summer holidays has been replaced with fertilizing in the spring and in September when summer cools off. Instead of using a high-nitrogen fertilizer, switch to a lower-nitrogen, slow-release fertilizer that releases its nutrients at a rate the grass can use it.

Set your mower to its highest setting during hot weather or don’t mow until it cools down. Lawns are not golf greens, and they need the shade cast by the leaf blades to cool the ground. If you have to cut it, leave the clippings on the lawn to provide shade. As a side benefit, they will break down and help fertilize the lawn.