What is Crabgrass?

Mary McMahon

Crabgrass is a type of annual grass that appears in the warm season. It is native to Europe, although it has colonized much of North America as well, to the dismay of many gardeners. The stubborn rooting grass can be difficult to eradicate when it colonizes, and it tends to overwhelm native species with an aggressive seeding pattern and rapid growth habit. As a result, most gardeners try to prevent crabgrass from emerging in their gardens, and take serious steps to eradicate it when it does.

Crabgrass has a rapid growth habit and should be removed by pulling up the entire root system.
Crabgrass has a rapid growth habit and should be removed by pulling up the entire root system.

The term can actually refer to several grasses, all of which are in the genus Digitaria. The two most common problem species are Digitaria sanguinalis and Digitaria ischaemum. Both have high growing branching stems, although they can also adapt to live close to the earth in mats. These mats will spread and put out roots within a season. If allowed to flourish, crabgrass tends to choke out the grasses surrounding it, and will form depressions in a lawn that are reseeded with the invader's seeds, allowing the grass to spread even further in the next season, especially if given ample water.

Vinegar may be used to control invading grasses.
Vinegar may be used to control invading grasses.

A number of steps can be taken to eliminate crabgrass, although constant vigilance is required. The first is to grow and maintain a healthy lawn that does not allow this grass to take root. Homeowners should plan on seeding, fertilizing, and watering in the early spring, before crabgrass emerges, so that the lawn can get a head start. Seeding should be done densely to create a thick mat of grasses to keep other species from getting a foothold, and water deeply and infrequently. Also, homeowners should keep the turf relatively high when they mow, as a lawn that is around 3 inches (7.6 centimeters) high will shade the crabgrass seeds, preventing them from sprouting.

When individual outbreaks of crabgrass occur, gardeners should make sure to remove each one by hand, pulling up the entire root system. Some gardeners use herbicides to control invading grasses, applying preemergent herbicides before it appears or control herbicides when it does pop up. The use of herbicides should only be undertaken as a last resort, however, as it can have an impact on the health of the rest of the garden, along with pets and children. Application of vinegar may also help, but homeowners should be prepared to kill the entire section of the lawn to which the vinegar is applied, and reseed or sod quickly before crabgrass can root again.

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Discussion Comments


I'm a country girl turned organic gardener/urban homesteader type living in the burbs and always thought that the way people around here fuss over their lawns was ridiculous. Then my lawn came under an invasion of crabgrass and I've changed my tune. I hate the stuff. It's ugly, clumpy, hard to mow, incredibly invasive and deep rooted and it's really ticking me off.

I never thought I would give a flying leap about what kind of grass grows in my lawn and weeds never bothered me either. But this stuff has to go! I don't use any chemicals on my lawn for the safety of children, pets, chickens, and the food we grow, but I fantasize about drenching that crap with something severely nasty and dangerous.


Why do people think they need to cut their grass so short. Especially in the summer, your grass needs to be cut longer to keep it healthy. It's best to let it grow several inches and and only cut off 1/3 of the height. Usually the highest setting on the mower (or second highest) is the best for keeping a healthy lawn.


I have a crabgrass lawn. I see people trying to grow other types of grass and spending a lot of money to do so. In the summer I don't worry about foot traffic, dogs or a good kickball game on my grass. I don't water, I don't fertilize and it grows. I do have to cut it, but not as often. It grows well here in ma. I do, however, have to edge to keep it out of my vegetable garden and keep it looking neat.


crabgrass isn't native either. reading is fun.


hello, I recently recommended someone who does landscaping to a friend. He ripped up his old lawn and placed sod down. The grass grew and looked beautiful. After about a week the owner of the grass mowed it down to about 1-1/2 inches. What happened next is the lawn is now filled with crab grass. The owner of the lawn says he was ripped off, and the sod was no good, my friend the landscaper says he mowed it down too short too soon, allowing the crab grass to get through. There was only a little of it before we started, but now the 90% of the lawn turned into crab grass. Whats your opinion?


Of course, lawns are not exactly native plants, so I'm not sure why people get upset about crabgrass in that respect.

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