By Charles Marr
Kansas State University
There is a little injustice in the world, when those of us that try to maintain our cool season lawns are "skunked" about this time of year by our neighbors who do nothing.
They now have a lush, green lawn, when our lawn is brown and dead looking. What is going on is that those non-attended lawns have become a sea of crabgrass and, for a week or so, crabgrass makes a very attractive, green lawn.
Crabgrass is an annual grass that has a broad, flat leaf and sprawls on the ground--spreading to a large clump from a single plant. It has a seedhead that protrudes upward and producers a lot of seed that will be there to plague you next year. Crabgrass starts to germinate in the early spring, when soil temperatures begin to increase in early May. However, this year, we had a very warm, dry early part of the growing season. In this case, crabgrass--that usually is close to the soil surface--did not germinate. Then, as we got some heavy rains over our area about a month ago, the crabgrass all germinated about the same time. The result is a profusion of crabgrass that is everywhere right now.
The reason crabgrass is such a problem in a cool season lawn is that it is an annual--it dies about the time of the first freeze and those dense, sprawling plants kill out other grasses, so there are large, bare spots later in the season.
Next year, the crabgrass areas won't germinate until later in the season and you are left with large, open spots in your lawn that aren't very attractive. You can't always count on crabgrass to germinate nice and evenly--all at one time, so the general appearance is a spotted, "patchwork quilt" appearance of the lawn.
Our cool season grasses tend to go dormant in summer heat and drought. Those people that have been watering or have their lawns growing in the shade still have some green grass, but others of us have a lot of brown areas over the lawn as we are dealing with hot, dry conditions over our region. When temperatures begin to break, the nights cool down and some late summer rains start to develop, the cool season grasses will start to do their thing once again and the lush, green lawn will reappear for the autumn season. Your lawn will remain green long after the crabgrass dies and will re-green early and vigorously next spring. So, you are lucky that you have a lawn after all and that you don't have to deal with crabgrass.
There have been some excellent, new developments with crabgrass preventers in recent year, with materials that last a lot longer through the spring season. However, in a year like this tone, even the best crabgrass preventers have failed a little bit and we are seeing a lot of crabgrass developing all over the central High Plains.
So, don't despair with your brown lawn this year. It is part of learning to live here, in the central U.S., with the hot, dry summers. You can have a short-term green crabgrass lawn, but the luster soon will fade and you will be a winner in the long run.