Don't stress out over your lawn this summer

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Last Updated: 
February 19, 2003

CORVALLIS - Your lawn: it's underfoot, but it's not understood.

Tom Cook, lawn expert at Oregon State University, can help you understand what happens to your lawn during the long dry days of summer, and what you can do about it.

Lawns in western Oregon don't require irrigation to survive, according to Cook. If you don't mind a brown lawn and a few more dandelions most lawns will green up again in the fall when the rains return.

In an average lawn, grass starts growing vigorously in spring producing both new roots and new shoots. When the spring rains subside and the days get warmer, grass slowly uses up soil moisture and new growth slows. As drought continues, older leaf blades die back and your lawn begins to turn brown.

After a long drought there may be a few green shoots attached to especially deep roots and an expanse of apparently dead grass. Unseen are dormant buds that are very drought tolerant. These dormant buds will grow again once adequate water is applied. When fall arrives, a dose of water and fertilizer will encourage recovery.

In general, the healthier the turf is when drought stress begins, the longer the turf will stay green and the better it will weather the drought. Lawns that have lots of thatch will be more likely to die out.

"The worst that will happen if lawns are not watered is that weaker parts of the lawn or areas in hot spots will die," said Cook. "When fall returns lawns can be reseeded and will recover just fine over the winter."

There are consequences to allowing your lawn to go dormant. After a summer of drought, turf density is effectively decreased because not all individual plants in the turf survive. What was once dense turf may become a clumpy stand peppered with invading broadleaf weeds, which are better adapted than ryegrass to prolonged drought. Also, drought may encourage chinch bug activity, but will keep European cranefly populations in check.

Cook offers this advice to those faced with a drought-stressed lawn:

"I would plan on fertilizing in fall with the onset of the rainy season to maximize re-growth of dormant turf. I would consider fall dethatching and overseeding to bolster the turf. In Oregon perennial ryegrass would be my grass of choice since it is quick to establish and has better than average drought tolerance. In the spring, I would monitor my lawn for broadleaf weeds and treat as needed."

And what to do when drought stress is toasting your lawn this summer?

"I would go fishing or play golf and not worry about the lawn."

If a green lawn is what you want this summer, consider Cook's approach to strategic watering.

Decide what parts of your lawn to keep green and to what extent. You may decide to water the front yard and let the backyard go dormant. Perhaps you only want a small green patch near your deck. Water that and let the rest go dormant.

A related strategy is to water only enough to keep the lawn more green than brown. With this approach the lawn is not crispy brown and is generally comfortable underfoot. Cook says he uses a combination of prioritizing lawn areas and practicing subsistence irrigation in his yard.

If your goal is to maintain a dense, green lawn, you will need to water regularly, but certainly not every day.

In hot weather, a Willamette Valley lawn will use about a quarter inch of water per day. In cooler weather it will use as little as a 1/10 inch.

"Blindly irrigating daily generally produces lush green lawns, but invariably applies too much water and grows too much grass," said Cook.

He suggests that you watch your turf for signs of drought stress and wilting. Use a screwdriver to poke in the soil in several places to get a feel for how dry the area is. Moist soil is easy to penetrate while dry soil is as hard as concrete. If the turf looks good and the soil is easily penetrated, you can wait a day and check it again before watering.

Cook says that lawns need less water to stay green once the days get significantly shorter, about mid-August. And he says you can really reduce watering amount and frequency shortly after Labor Day.

In the event of serious drought, you have several options:

  • Do nothing but mow your lawn until it is completely dormant. Lawns throughout the Willamette Valley and the coast will recover with the first rains in fall. However, lawns in parts of central, eastern, and southwestern Oregon may not survive if water is withheld for the entire summer period.

  • Irrigate your lawn as little as once every two weeks. This will generally keep the lawn alive although not uniformly green, even in the drier parts of Oregon.
  • Prioritize the lawn areas. Water small and important areas as needed to provide acceptable turf. Apply minimal water to less important lawn areas and none at all to peripheral areas.
  • Remember that most of lawn watering is common sense. Water on days when the weather is really hot. And slack off when it is cooler. And don't forget that even if you don't water at all, your brown lawn will survive and turn green when the rains return.
Author: Peg Herring
Source: Tom Cook