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How do I care for my dormant cool-season lawn?
Lawns that turn brown in mid-summer may cause you needless worry and work. The cool-season turf grasses we use in Missouri, such as Kentucky bluegrass, fescue and perennial rye will naturally go dormant and turn brown in mid-summer due to lack of water or too much heat. When this happens you can maintain the lawn in its dormant state throughout the summer with a minimum amount of care.
Mow your lawn regularly with a sharp mower and water during extended dry periods. The lawn will remain brown, but alive. In fall it will green up again. When mowing, do not mow bluegrass, fescue, rye or any cool season grass lower than two and one half inches. A three inch height cut is even better.
If you wish to keep the lawn green all summer you will need to follow a regular watering routine before the lawn begins to brown as once the lawn goes dormant in mid-summer watering will not generally green it up until fall. To keep the lawn green requires about 1 inch of rain or irrigation per week. A sprinkler used on home lawns usually delivers from one-quarter to one-third inch per hour. It is better to give the lawn a good soaking (a 6-inch depth) once a week than frequent light watering. Watering should be done early in the day to reduce the occurrence of disease in your grass.
It is not necessary to fertilize in mid-summer. If broadleaf weeds are a problem on the lawn during mid-summer, wait until early fall to control them. Chemical treatments for weeds in mid-summer may further damage your desirable turf and will work much better in the fall.
The following table gives the amount of water needed to keep a lawn from going dormant and how much water is needed to keep a dormant lawn from dying.
| Table 1. Approximate water requirements for various lawns. |
| Lawn type |
Green Turf¹
inches of water per week |
Dormant Turf²
inches of water per week |
| Perennial ryegrass |
1.5 |
1.0 |
| Kentucky bluegrass |
1.2 |
0.7 |
| Tall fescue |
0.8 |
0.5 |
| Zoysia grass or Bermuda grass |
0.5 |
0.2 |
| Buffalo grass |
0.3 |
0.2 |
¹Lawn remains green and growing
²Lawn may turn brown, but will not die |
From Missouri Environment and Garden, May 23, 2012