Weed of the Day No. 12 - Crabgrass

With a whole new crop of weeds and not a lot of time to investigate them, I decided to choose a familiar and annoying pest for today. This is Digitaria, or as you and I know it, crabgrass.

I couldn't begin to tell you which of the 300 species of crabgrass this is. My guess is that it's Digitaria sanguinalis or large crabgrass but the devil is in the details, as they say, and the differences in this plant lie mostly in the flowers, seeds, and subtle variation in leaves.

My scientific curiosity does not go so far that I'll let this weed fulfill its life cycle to find out what kind it is.

You can tell crabgrass in your yard or garden by its very low and spiky appearance. The leaves are 2 to 5 inches long, a quarter to a half inch wide wide and roll out of the stem like a green, annoying party favor. It spreads out to form mats which can grow quite dense and it has the ability to root itself wherever one of the nodes (those spots on a plant where a stem grows out of the main branch) touches the ground. If it does get so far as to produce flowers, they form familiar spiky fingered whorls at the ends of the plant. I remember bugging my sister with crabgrass blossoms when we were kids. They make excellent younger sister ticklers.

Crabgrass likes to grow in warm, moist, sunny environments and doesn't mind compacted soil and poor nutrients. As you can see from my little friend, it will even grow up through cracks in pavement and seems to do quite well for itself despite the harsh conditions. Imagine what it would do if I gave this guy a little bit of fertilizer.

This is the White Whale of weeds for those folks on the quest for the perfect lawn. There are three varieties are on the USDA noxious weed list and the rest are not invasive enough to be considered dangerous at this time. The only way to control its spread without the use of herbicides is to make sure the growing conditions in your yard don't encourage it to set up shop.

The first step toward a crabgrass free lawn is to grow the right kind of turfgrasses for your yard. If your turf is green and lush and healthy, it's much harder for crabgrass to get the light it needs to grow. Don't cut your lawn too short for its type. The University of Ohio Extension service has an interesting piece on lawnmowing in general which also list optimal mowing heights for some grass varieties. Finally, there is always the good ol' standby of pulling the weeds from the lawn before they go to seed. Because crabgrass grows roots where it touches the ground, make sure you get all the plant parts.

I didn't expect to find any useful properties of crabgrass but as it turns out, as with most things in life, there's a reason for it after all. A member of the Digitaria genus known as fonio is a staple food crop for West Africa. The seeds can be ground into flour and used in all manner of dishes.

If only that were the kind growing in my walkway.