Letting a lawn go dormant in summer
Cool-season grasses can stop growing in a dry summer and turn the color of straw, then green up again when rain and cooler nights return. Allowing that saves water, as long as the lawn is left alone while it rests.
Published 2 min read
Lawns of Kentucky bluegrass, ryegrass and fescue grow best in spring and fall. In a long dry spell in midsummer many of them do something that looks like dying and is not: the blades stop growing and turn brown, while the crowns, the growing points at the base of each plant, stay alive. When moisture comes back, new leaves grow from those crowns. Keeping such a lawn green through July and August takes a great deal of water. Letting it go dormant takes very little.
Which grasses can do it
Not every lawn grass handles dormancy equally well. Nebraska Extension’s guide to drought effects on turf, issued in 2013, singles out Kentucky bluegrass as a species that avoids drought damage this way. Tall fescue takes a different route. Its roots can reach three feet down where soil allows, so it stays green longer on stored water. Nebraska Extension advises that a tall fescue lawn turning brown all over is more likely dying than dormant, and needs water.
In the Pacific Northwest the choice is easier. An Oregon State University Extension publication on turfgrass irrigation says that perennial ryegrass, tall fescue, fine fescues and Kentucky bluegrass can all be kept in western Oregon without any irrigation, provided the owner accepts summer dormancy and some drought-tolerant weeds such as dandelion and crabgrass.
How long it lasts
Dormancy is a survival state with limits. The Nebraska guide puts typical survival at four to five weeks, falling to three or four weeks when temperatures stay above 80 degrees Fahrenheit. A lawn that will stay dry longer than that needs a little help. Nebraska Extension suggests between 0.25 and 0.5 inch of water every two to three weeks. That amount is meant to keep the crowns hydrated without bringing the lawn back to green.
The second rule is not to start and stop. Ohio State University’s turfgrass program, writing during the Ohio drought of 2024, advised that once a dormant lawn is being watered back to green, the watering should continue on a regular schedule, since a lawn that greens up and then dries out again is stressed twice.
Feet matter more than color
Nebraska Extension’s advice for dormant bluegrass is to limit foot traffic and mowing so the crowns are not damaged. Drought-stressed grass does not spring back after it is walked on, and footprints and wheel tracks stay visible. Ohio State’s advice from September 2024 was to stop mowing dormant and drought-stressed lawns altogether, since the cut itself is a stress and the mower adds foot and tire traffic. Fertilizer can wait as well. A dormant plant takes up little water, so it cannot absorb nutrients, and the granules sit on the surface until rain comes.
A play area, a dog run or a path across the grass is the part of a dormant lawn most likely to come out of summer thin. Those spots are the place to spend water, while the rest of the lawn is left to rest.
After the rain
Green-up starts once rain returns and nights cool, though it takes time. Oregon State notes that unirrigated lawns are more open to broadleaf weeds and usually need some attention in the fall. That is the season to reseed thin patches and feed the lawn, once it is growing again.