Dealing With Crabgrass: Advice For Gardeners

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North American gardeners must often contend with a range of persistent garden weeds. Some of the most problematic plants can stifle your attempts to grow a healthy lawn, so determined gardeners must develop a plan of attack against the most common pests. Crabgrass is a common weed that plagues gardeners across North America, but, with the right strategy, you can rid yourself of this problematic plant. Learn more about how to spot crabgrass, and find out how you remove this weed from your lawn.

Types of crabgrass

Crabgrass can grow almost anywhere in the garden. You'll find the weed in lawns, flower beds and vegetable gardens, and larger plants can even cause problems on agricultural land. Gardeners have several names for this weed, including crowfoot grass, watergrass and summer grass.

The most common types of crabgrass are:

  • Smooth crabgrass. This weed's leaves are light green and smooth to start with, and develop into dark green plants. A fully grown leaf blade is around a third of an inch wide, and up to 5 inches long, and has a distinctive, pointed shape. The upper side of the leaf is smooth, but the lower leaf surface sometimes has a few hairs. You may sometimes see a reddish tint at the leaf base.
  • Large crabgrass. Left alone, a large crabgrass plant can grow up to two feet tall. New leaves are light green and hairy, and will grow to around three inches long. The flower stalk resembles smooth crabgrass, but this species has longer branches at the end of the stalk. According to the University of California, one plant can produce as many as 150,000 seeds.

Life cycle

Both species of crabgrass are low-growing, annual summer plants. The weeds spread by seed and from parts of the plant left in the soil. The plants will normally die when frosty weather sets in. Germination occurs early in the year where the winters are mild, and plants can produce a second crop of seed if there is no frost.

Crabgrass can damage healthy lawns, and the plant will thin out your turf during the summer when water is scarce. Once the lawn thins, the plant can quickly flourish. If your lawn is unhealthy, crabgrass can take over in one season.

Management of crabgrass

You can manage crabgrass in turf with chemical herbicides. Pre-emergent herbicides are more effective, as they will prevent the plant taking hold, but if you have a crabgrass infestation, post-emergent herbicides can help.

Pre-emergent herbicides that gardeners can buy include benefin, bensulide and trifluralin. You should apply the herbicide before the plant germinates, which is often during the first week of March. In some climates, you may need a second application, so follow the label directions carefully.

Gardeners can buy few post-emergent herbicides that can tackle crabgrass, and garden store solutions aren't always effective. Professional weed control companies are able to use more powerful herbicides, so you may need to pay an expert to help you deal with an existing crabgrass problem. That aside, herbicides that tackle crabgrass can also damage the turfs, so carefully consider your options.


Effective lawn management can significantly cut the risk of crabgrass growth. Your best defense against the weed is to cultivate healthy, thick turf, as this will make it harder for crabgrass to grow. Mulch areas where crabgrass has previously grown. This can prevent crabgrass seeds germinating. Use the mulch sparingly, as compacted areas will limit turf growth as well.

You can also pull the weeds out by hand. The quicker you get rid of the plants, the harder it is for their seeds to germinate. At the end of the season, you can then consider a pre-emergent herbicide. Regular irrigation is also vital. Overwatered turf is weak and vulnerable to the weed, but light, daily watering will also have the same effect. Aim to irrigate the lawn thoroughly once a week, making sure the water reaches every part of the turf.

Crabgrass causes problems for gardeners across the United States, but you can easily stop the weed taking hold. Develop a robust strategy against crabgrass, and enjoy a healthy, weed-free lawn. If you have questions and want to get in touch with a weed management company, try visiting


30 October 2014