Crabgrass is a seasonal weed that can grow prolifically in a lawn. It is one of the most common weeds found in lawns and is difficult to eliminate because of its abundant seeds that become embedded in the soil when homeowners attempt to pull the grass out of the ground.
TIP: Our expert gardening advisor Kathy Bosen adds, "Unless you have a huge yard and a big crabgrass problem, hand weeding can be a simple and safe solution. Dig the crabgrass out before seeds emerge, and fill in the spots with fresh grass seed. Maintaining a healthy yard is the best way to prevent crabgrass."
Crabgrass is easy to identify in a lawn because of its distinctive “crab” appearance. Blades of the grass grow in spiky clumps and can grow as tall as 3 feet or more. The weed often grows in mats and has broad spiked leaf blades. The smooth variety grows in smaller patches, has shorter spiky leaf blades and usually only grows about 15 inches in height.
Crabgrass is usually a lighter green color than the surrounding grass and can be found where the lawn has been overly mowed, where is a bare spot and in overly moist areas.
Treating the Problem
The best time to treat crabgrass with herbicides is Spring because its growing season has just begun and it has not had a chance to establish itself in your lawn. Herbicides stop crabgrass as soon as the weather begins to turn warm. Apply the herbicide to crabgrass patches according to the package's instructions.
You will probably need to repeat the process several times throughout the growing season, including at least one application during the summer. You can apply a longer lasting herbicide that contains a grass feeder, to help promote lawn growth while killing the crabgrass.
If you prefer to avoid putting poisons like herbicides on your grass because of organic concerns or because you have children or pets that play frequently on your grass, you can try an old master gardener trick of pouring boiling water directly on the crabgrass. While this may sound strange, it is a very effective method of getting rid of crabgrass and weeds with short root systems. Within a few days the grass should turn black and die. The boiling water method can be very effective if you use it early in the season, before the crabgrass has the opportunity to establish itself in your lawn and put out seeds for the next spring.
Besides killing the seeds before they can begin to germinate, there are a few other methods to prevent crabgrass entirely. The first is to allow your grass to grow a few inches taller than usual and not mowing it extremely short. Since crabgrass needs sunshine to thrive, you will stop if from growing if you deny it sunshine.
Another method to prevent crabgrass is to continually reseed places in your lawn where the grass has grown thin or there are bare spots. Without bare spots, it will be difficult for crabgrass to become established.
While fighting crabgrass can be a constant battle for homeowners who take pride in their lawns, using good lawn maintenance methods will eventually get rid of the problem.