Crabgrass is a familiar frustration to many of us here in Ohio. It's a stubborn, grassy weed that can be complicated to prevent and challenging to eliminate once it's settled in. In today's post we'll go over the information you need to know to manage crabgrass effectively.
Crabgrass is an annual weed, which means that it spreads by seeding itself every spring. Although at first newly sprouting crabgrass can resemble blades of grass, don't be fooled! As it grows, the plant stalks grow outward from a central point, and the stalks take sharp turns which look like a crab's legs (hence the name!).
The best way to manage crabgrass is to prevent it before it takes root in your lawn, and this can be done in a couple of ways:
Pre-emergent herbicide. When crabgrass seeds germinate, they need a certain enzyme for the process. Pre-emergent herbicide works by inhibiting this enzyme, but it must be timed carefully to work properly. Timing the pre-emergent can be tricky: crabgrass seeds germinate when the soil temperature rises to a certain level. A good guideline to follow is that when the outside temps have been 60-70 degrees for four consecutive days, it's time for pre-emergent. Another trick: when the forsythia trees are in full bloom, the soil has warmed up enough to apply pre-emergent herbicide.
Healthy grass. Crabgrass loves direct sunlight and thrives in heat. If your lawn is thinning or has bare spots in it, they are a prime spot for crabgrass to settle in for the long haul without grass around to cramp its style or block its view of the sun. A thick, healthy lawn can help prevent crabgrass on its own by simply not giving crabgrass anywhere to squeeze its way in. Lawn aeration and overseeding are two services that can revitalize your grass. If you do any seeding, keep in mind: you will need to make sure that you are not applying pre-emergent herbicide too close to when your new seed is going down!
Even the best-timed pre-emergent can miss straggler crabgrass seeds, so if you do find yourself dealing with crabgrass afterwards you'll need to apply a post-emergent herbicide. Remember: crabgrass is an annual weed which seeds itself, so the sooner you treat crabgrass upon discovery, the better!