Crabgrass (Digitaria) was introduced to the U.S. in 1849 by the U.S. Patent Office as a potential forage crop. Opps! That was a mistake. Although crabgrass is highly nutritious, not many farmers in America cultivate the grass like they do in Eastern Europe, Africa and India.
Here in Iowa, we commonly see Smooth Crabgrass (Digitaria ischaemum), and Hairy or Large Crabgrass (Digitaria Sanguinalis). Hairy crabgrass has hairs on the leaves, whereas smooth crabgrass does not. (I’m very proud of my industry’s creativity when it comes to naming things). This little tropical plant is actually quite amazing. It takes just a few days of consecutive ground temperatures at 50 degrees or above for the seeds to germinate.
Crabgrass starts out small and really doesn’t start to take over until the weather gets warmer. If you have seen lime green leaves in your lawn occur around late May, chances are you have seen crabgrass. Once the weather gets warmer crabgrass starts to produce tillers and spread out, resulting in choking out our desired turf and other weeds. As our summers turn up the heat, cool season grass slows down its growth rate. This is when crabgrass grows at its best and can take over in just a short period of time. Luckily because this plant is an annual, meaning it does not overwinter, the first frost will kill it. The bad news is before it dies one plant can produce up to 150,000 seeds.
Behind dandelions, crabgrass is the weed that everyone is concerned about controlling. The most effective way of keeping this little guy out of your lawn is taking action in the spring before ground temperatures reach 50 degrees. This is why many homeowners and Lawn Care Operators (LCO’s) are busy in the early spring getting their pre-emergent down, to not miss the window of opportunity to control this invasive plant . Because this little plant is so prolific at producing seeds it won’t be long before it takes over your lawn if remained uncontrolled, especially if there are bare spots.
If your lawn is overrun by crabgrass, it’s best to call a professional you trust who can help you plan how to bring your lawn to the envy of the neighborhood.