Preventing Crabgrass in the Lawn
My bluegrass yard was full of crabgrass last summer. How can I keep it under control, preferably without using chemicals?
The best defense against crabgrass or any weed is a healthy lawn. Keep the grass 2 1/2 to 4 inches tall. The taller grass shades out the weed seeds preventing many from sprouting. The longer grass is also more drought tolerant and better able to compete with the drought tolerant crabgrass. Proper watering, especially during dry periods, will keep the grass actively growing as the crabgrass tries to move in.
If this does not keep the crabgrass in check you may want to use corn gluten meal to help suppress this and other weeds. The University of Iowa found corn gluten meal was effective at reducing seed germination while adding nitrogen to the soil. You won't have complete control but most reports show a 91% reduction in crabgrass and a 50% reduction in all weeds over a three year period. A spring application (when forsythia are blooming) will help reduce problems with crabgrass and other spring and summer weeds. Fall applications prevent sprouting of winter annuals and other weeds. Keep in mind these products will also prevent desirable grass seed from germinating, so wait until late summer to overseed spring treated areas. And even though this is a plant derived product, be sure to read and follow all label directions carefully.