About Crabgrass


Found across lawn nationwide, crabgrass is one of the most common weeds. It is an annual weed that germinates in the summer when soil temperatures average about 60 degrees Fahrenheit for at least three consecutive days. Crabgrass begins to flower between late June and early July, and it dies off with the first frost of the fall season.


Crabgrass can germinate from mid spring through summer's end under the proper temperatures. Though a cooler soil temperature promotes its germination, it can germinate in temperatures as high as 95 degrees Fahrenheit. It reproduces primarily through seed germination and can create deep rooting systems.


Crabgrass has a varying bluish-green color with rough edges and margins. The edges are often pointed and can grow to be up to 6 inches long. At times, crabgrass will produce flowers. These flowers are usually a purplish color with spiked edges, also growing up to 6 inches in length. The flowering process occurs between August and September at the height of the crabgrass lifespan.

Controlling Your Crabgrass

The reproductive survival of crabgrass is quite resilient, making it very difficult to completely kill all growth. Therefore, the best way to control and reduce crabgrass is to focus on healthy grass. A healthy lawn with dense turf will compete with the crabgrass and reduce its growth. Mow your lawn frequently, irrigate deeply, and water infrequently. Water your grass so that the soil is wet deep down to the root of the grass and then do not water again until the grass shows signs of drought stress. Fertilize your lawn in the fall and after your last fall/winter mowing. This will help to create grass density. Do not fertilize in the summer, as this will improve the crabgrass' productivity.


Though natural maintenance is recommended in reducing and eliminating crabgrass, herbicides may be necessary. Herbicides are especially recommended for new or thin lawns because these lawns to not have the proper rooting and density to fight off crabgrass growth. Choose your herbicides based on the life of the crabgrass. If you are fighting crabgrass that has yet to appear, choose a pre-emergence herbicide. These herbicides are designed for crabgrass that has yet to root and should be used in the early spring, before crabgrass germination. Post-emergence herbicides are designed for use after the crabgrass has rooted. They are more difficult to use and require more grass preparation. Water your grass generously before applying the herbicides and do not water or mow your grass for at least 24 hours after application.

Garden & Plant Bed Control

Crabgrass will take over your garden or plant bed if not properly tamed. To reduce, if not eliminate crabgrass in your gardens and beds, hand pull the crabgrass from the soil, being sure to capture the root. Use mulch and compost around the areas to block the sunlight and germination of seedlings. If germination occurs in the mulched area, remove the mulch, hand-pull the crabgrass, and reapply the mulch.

Keywords: crabgrass, how to kill crabgrass, crabgrass control

About this Author

Writing professionally since 2004, Charmayne Smith focuses on corporate materials such as training manuals, business plans, grant applications and technical manuals. Smith's articles have appeared in the "Houston Chronicle" and on various websites, drawing on her extensive experience in corporate management and property/casualty insurance.