August 2, 2008 in Voices

Lawns require care during heat of season

Pat Munts Staff writer

The heat of summer is upon us. We all scurry for the shade on a hot afternoon. Local beaches are crowded with folks cooling off in the water.

Our lawns aren’t so lucky. They are stuck in the heat of the day at the mercy of whatever care and water they get. A little care and a change of some habits now will help get it through the worst of the heat.

Skip the fertilizer from now until September. Most lawns grow much more slowly when the temperatures are regularly above 80 to 85 degrees so the lawn really can’t use it. They will need it in September when the weather cools and we get some rains. Then use a slow-release fertilizer blended for fall application with the numbers in a ratio of 3:1:2. This will green-up the lawn gradually and keep it from growing too fast. That means less mowing for you.

During the hot part of the summer, let the grass stay long. By leaving the grass longer, it helps shade and cool the ground which actually cuts down on water use by the lawn. Fescues and bluegrass should be cut at 3 to 3 ½ inches during the hot part of the summer. Mow often enough to remove only one-third of the grass’s height at a time. Sharpen the mower blade every six weeks. Dull blades tear the grass and open it to more water loss.

Check your sprinkler heads and drip lines for damage or plugs. The first sign you will have that there is a problem is when plants are wilted or dying, which may be too late. Try to water in the evening or early morning to cut down on water lost to evaporation.

Most lawns will need at least 1 ½ inches of water a week during the hottest part of the summer. To determine how much water you are getting on the lawn, set out some tuna or other flat containers around the yard and see how much water is collected after the sprinklers run. Then set your system accordingly to get that amount. It is better to water for longer periods to get water deep into the soil. This also means you can water less frequently.

Wait until September to do any lawn reseeding. Tiny new grass plants need to be kept moist and the afternoon heat makes that difficult unless you can set your sprinklers to come on a couple of times in the area. Sod can be laid but keep it moist until it has a chance to begin sending out roots.

Like the grass, weeds slow their growth when it’s hot. So it may be better to wait until September to do major weed control projects. Because of the slower growth, herbicides aren’t carried through the plant as efficiently, making control more difficult. Additionally, when it is above 80 degrees, herbicides can vaporize more readily and the vapors can drift, damaging other plants.

Pat Munts is a Master Gardener who has gardened the same acre in Spokane for 30 years. She can be reached at

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