Hi! I'm in really sandy soil in Ramsey, mn. I have been regular with fertilizing with a weed and feed and proper watering during dry spells this year, but did not use a pre emergent crab grass fertilizer this year and am now paying the price! In the past 3-4 weeks I have crabgrass sprouting or well established in so many places where it has never been before, I have a very large mowing area and can't treat all of it but would like to at least feel like I can get some kind of control on a good portion of it without going broke in doing so. What is the best herbicide that I can use to wipe this stuff off the map without damaging the good grasses? I know farmers if it's a specialty item only available to ag producers but would like to find something that a good nursery or garden center or co-op would carry. Thank you for your time, Jimmy
Anoka County Minnesota
It will be important to be sure you are dealing with crab grass. It is often confused with quack grass. The following explains some of the differences.
I will answer your questions assuming that you indeed have crab grass.
The following sites will provide information with respect to dealing with crabgrass:
In the above sites you will see reference to post-emergent herbicides. If you go this route, be sure to get a herbicide whose directions indicate that it is safe to use on regular grass but still kills crabgrass. As volunteer Master Gardeners associated with the University of Minnesota, it would not be appropriate for us to recommend one or more specific commercial products.
Crab grass sows its seeds in August and September. These seeds will then germinate in the following spring. Since crab grass can then appear year after year, it is easy to think of it as a perennial.
The pre-emergent herbicide should be applied as early as possible in the spring. The goal is to have this herbicide present before crab grass seeds germinate. A pre-emergent herbicide is to retard this germination.
The post-emergent herbicide could be applied now and extending into early September. The goal here is to kill the crab grass before it disperses its seeds.