By this week in August EVERY YEAR almost universal afflictions seem to overtake lawns: They’re either baked out brown, overrun by crabgrass, or both. Sometimes people phone us and we hear the desperation in their voices; most times they email begging for help, as if there’s a magical solution.
In a line: Don’t Fret and BE PATIENT
WITH REGARD TO THE CRABGRASS your best bet is to understand that the plant is an annual and it will be dead as soon as we have our first frost, which depending on where you live can be four to 12 weeks from now in the temperate zones of the nation. Spending time treating it with an herbicide just makes no sense.
The best thing you can do is to learn why you have so much crabgrass, or goosegrass or similar annual plants. It’s almost assuredly due to one of two reasons: your lawn mower and your watering regime. Soil has something to do with it, too, but the mowing and sprinkler are always the first things to look at.
In a nutshell, the mower should never be set below its highest setting at anytime during the mowing season until after the first frost. Mowing low opens the soil under the lawn to all kinds of sunlight, which causes the crabgrass seeds to germinate. Once that happens, look out. You’re going to get crabgrass, which just loves the heat of summer as much as the cool-season grasses (bluegrass, fescues etc.) don’t like it. Right now the crabgrass is thriving just as the lawn grasses we want are probably trying to go brown and dormant.
Secondly, your watering should be restricted to once every five to seven days depending on your soil type. Too frequent waterings will cause crabgrass to continue to germinate throughout the summer.
If you water infrequently, but deeply, the roots of the grass plants learn to grow downward to get their moisture; crabgrass roots are shallow and won’t compete as well if the moisture is 6 inches deep or more.
The simple test is to take a shovel and dig up a small patch of your lawn where lawn grass is growing; get down all the way to the bottom of the roots to see if the soil is moist. If not, water some more . . . until the soil is moist to the touch to beneath the root zone. Then don’t water again for at least five days; you’ll be able to stretch this out longer if your soil contains a lot of clay rather than sand or silt.
AS FOR DROUGHT AND BROWN LAWNS in most cases you can be assured that the lawn isn’t dead, it’s just dormant. Turning brown is a grass plant’s built-in mechanism for survival during periods of time when no natural rainfall occurs. As long as we get at least some moisture in the next six or eight weeks, the lawn will come back to green sometime in September.
If, in the worst case scenario, it is dead it still makes no sense to try to do anything about it in August. Plan a renovation for after Labor Day.