University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Helping Lawns Through Summer Stress

June 19, 1997

With the official arrival of summer on Saturday, it's once again time to review the basics of helping lawns thorough dry and hot conditions that could occur over the next several weeks. Typical 'dog days' of summer can put considerable stress on lawns.

The vast majority of home lawns in northern Illinois contain cool-season grasses, such as Kentucky bluegrass, which go dormant (stopped active growth, turn off-color) in response to drought conditions. Once lawns turn brown, it's actually best to leave them in that condition rather than watering heavily to cause the grass to green-up again. Breaking dormancy drains food reserves within the plant, which are hard to replace in the heat of summer.

Lawns can be watered to keep them green for the summer; but it's important to do it properly. Watch for footprinting--or footprints remaining after walking across the lawn. This indicates grasses are starting to wilt and need water. Water thoroughly to the depth of the root system and allow conditions to dry before watering again. Try to water early in the day.

In most years, lawns go dormant and resume active growth when conditions improve. But if it's very dry, how much water is enough to keep the turf alive? Applying 1/4 to 1/2 inch every 2 to 4 weeks should be enough to maintain moisture in stems and roots so the grass can survive and resume growing when conditions improve. Drawbacks of dormancy include looking at a brown lawn and the risk of problems arising on the inactive lawn, such as weed invasions.

Whether watering the lawn or not, mowing has a big impact on lawn health in summer. Mow lawns higher for the summer, to help reduce stress and keep weeds out. A range of 2.5 to 3 inches would be suggested for cool-season grasses.

Wait until the early September period for fertilizing most lawns, rather than summer. Use fertilizers providing adequate potassium, in addition to nitrogen.

Drought stress will occur faster on lawns receiving poor care or growing under adverse conditions. Mowing too short and poor soil conditions (compaction, clay fill) often are the reason a lawn declines quickly in the heat. Work on improving all areas of lawn care to help keep lawns looking good in summer. For additional lawn care information, visit Lawntalk on this website.

 

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