Treatments for crabgrass run from more natural methods to those that involve buying herbicides and chemically treating the lawn. No matter which method, or combination of methods, is chosen, crabgrass is a persistent species, especially in areas where it has little competition. Therefore, always keep a close watch on your lawn and stop crabgrass invasion as quickly as possible. Treating a larger lawn problem is more time consuming and difficult.
Perhaps the most common method for treating crabgrass is to use a pre-emergent herbicide in the late winter or early spring. This should be done prior to the soil temperature reaching approximately 60 degrees F for several consecutive days. This method is particularly effective because crabgrass cannot survive freezing temperatures and seeds remain dormant over the winter period. Pre-emergent herbicides prevent the grass seed from germinating.
For those in warmer climates, or those who failed to treat with pre-emergent herbicides, the next option may be to use a post-emergent herbicide. This can kill grass that has already sprouted and grown, but it will also kill any other grass that it touches, so it should be used only in spot treatments or in areas where the grass is established in a widespread pattern. In general, if the crabgrass will die off in the winter, that is a better choice than using a post-emergent herbicide.
This method of treating crabgrass is a more natural method and does not rely on harsh chemicals. It involves leaving grass at a height of 2 inches or more. This will help choke out crabgrass, which is an invasive species but often not very competitive with other grass species, as long as those other species are of sufficient length.
There are a couple of different ways shading can be used to control crabgrass. Trees and shrubs are among the most scenic and natural ways to control crabgrass, because the species prefers full sunlight. This will also require finding a shade-tolerant species of grass to go around the trees and shrubs.
The other method involves utilizing newspaper, landscaping fabric or some other material to block the sun. This will kill the crabgrass and allow for a replanting. Sod can be planted, or it can be seeded a month after the crabgrass has been killed and a pre-emergent herbicide has been put down.
Crabgrass can also be pulled by hand for those who have the patience and time to do it. This is the most labor-intensive lawn care process and involves persistent monitoring, as newly germinated spots should be pulled as quickly as possible to prevent further seeding.