Crabgrass is like a bully on a playground, pushing weaker kids out of the way and taking over the jungle gym. But those traits can come in handy if the bully grows up to be a professional football player or a doctor saving lives. It's the same with crabgrass; in the right setting, it has its purpose.
In the United States, we usually refer to crabgrass as a weed. But what does that mean exactly? Did you know there's actually no botanic or scientific classification for weeds? They're simply plants we don't want around. And they are often invasive, crowding out plants we do want around.
Crabgrass is unpopular with many home gardeners because its ungainly clumps invade and crowd out desirable grasses like Bermuda and the cheerful dichondra. Plus, the two most prevalent types, smooth crabgrass and large crabgrass, grow to 15 to 36 inches (around 38 to 89 centimeters), respectively, if not mowed. And maybe that's the real reason we don't like it: When you don't mow it, your yard looks terrible.
But these traits -- its perseverance even in poor soils and its fast and high growth -- make it ideal in some parts of the country as a summer forage grass for cows, sheep and horses. According to the University of Florida, grazing animals find crabgrass quite tasty [source: UF]. That means they eat more and thus gain more weight than when grazing on millet, sorghum or other summer grasses and grains.
One tasty species is Red River, which can yield 125 pounds (a little more than 56 kilograms) of grass per acre per day under moist, fertile conditions [source: Kansas Rural Center for Sustainable Agriculture].
Whether you want to cultivate crabgrass for your cows to chew on or get rid of it to allow your lawn to thrive, find out what you need to do to either help crabgrass thrive or make it go away.
The Lowdown on Crabgrass Pros and Cons
Even though crabgrass is invasive, it's not actually competitive. That means it won't push thick, lush, healthy grass out of the way. But if you allow your lawn to become weak and unhealthy, crabgrass is standing by to take over.
Crabgrass is a summer annual, meaning that in most climates it grows one year, produces seeds, and then dies off. The next year, the seeds sprout and the cycle continues. In temperate climates, the crabgrass will grow two years. It also spreads by putting out runners, which sprout roots where they touch the ground.
To prevent those seeds from germinating, experts at Purdue University suggest keeping a grass lawn healthy, thick and lush [source: Purdue]. That means watering deeply and infrequently, rather than sprinkling often, which produces shallow roots vulnerable to crabgrass infestation. Also, a healthy lawn should be mowed no shorter than 2 or 3 inches (5 to 8 centimeters). Shorter than that gives crabgrass an opportunity to move in and make itself at home.
You can also use chemicals to keep crabgrass seeds from sprouting. Those are called pre-emergent herbicides. Once the seeds have sprouted, your best option is to pull the crabgrass out by hand.
Because there are 235 species of crabgrass and it grows in all 48 continental states of the United States, it's probably unrealistic to think the crabgrass could ever be eradicated from one's life. But knowing how delicious it is to cows and horses might make it seem a little less vile. And the next time you dine on "grass-fed beef," consider that the grass may be a little crabby.
For lots more information on crabgrass, landscaping and related topics, dig through the links on the next page.
Related HowStuffWorks Articles
More Great Links
- Crabgrass as a Forage and Hay Crop, University of Florida Extension. http://edis.ifas.ufl.edu/AG195
- Control of Crabgrass in Home Lawns, Purdue University. http://www.agry.purdue.edu/turf/pubs/AY-10.pdf