How can I get rid of crabgrass?

The solution to ridding your lawn of crabgrass is to attack it in two stages. First, apply corn gluten meal, an organic preemergent herbicide. Do this in the spring, when the soil is still cold and the crabgrass is weakest. (Crabgrass is an annual weed, so it starts from seed every year. The preemergent herbicide prevents the seed from germinating—and if the seed can’t sprout, it can’t grow.) Second, reseed your lawn in the fall. This will allow the new grass time to grow strong before the next summer’s attack.