Crabgrass is among the most stubborn of all lawn weeds, as it can come back with a vengeance year after year if the lawn isn’t treated properly.
Known for its “crab-like” appearance (i.e., growth close to the ground with a central stem and blades that resemble the legs of the crustacean), crabgrass seeds tend to germinate in the spring months unbeknownst to many property owners. Then, during the summer months when the days become hot and dry, crabgrass plants can really grow to take over what appears to be an otherwise healthy lawn.
Crabgrass will eventually die in the fall months when temperatures don’t favor its growth any longer, but often not before laying down plenty of weed seeds that are likely to restart the infestation all over again in the spring.
The good news is that if you know what to do, it’s fairly easy to prevent crabgrass and other broadleaf weeds from overtaking your lawn. In this post, we’ll take a closer look at how to identify, prevent and kill the crabgrass plant.
What is the lifecycle of Crabgrass?
Crabgrass seeds are shed from the plant every year towards the end of summer to early fall. These hearty seeds lay dormant in the soil over winter and begin to germinate when the soil temperatures reach optimal conditions in the springtime. This is usually when the soil temps are consistently 55 degrees Fahrenheit or warmer, for five consecutive days. In Massachusetts, this is usually in early April.
Identifying Crabgrass in Lawn Grass
While some may dismiss it as nothing more than a strange grass clump, crabgrass is a weed that resembles a crab. It’s characterized by a stem in the middle of the weed and blades emanating from it resembling crab legs.
Crabgrass thrives in dry, hot weather – so it tends to appear in lawn grasses in the mid to late summer months. Because of how crabgrass seed spreads, usually there’s always more than just a single crabgrass plant.
The way crabgrass seedlings spread and germinate and its designation as an annual weed underscore the importance of properly treating crabgrass to prevent it from overtaking cool-season grasses year after year.
How To Kill Crabgrass
How do you get rid of crabgrass without damaging your lawn? Prevention is key, and we’ll get into various pre-emergent herbicides and other crabgrass preventers in the next section. But there are a few ways to eliminate existing crabgrass sprouts without doing damage to your lawn. Here’s a look:
- Spot treatment: Use a good selective post emergent herbicide or crabgrass killer herbicide for spot treatment on your lawn. Chemicals will include quinclorac (Drive XLR8), mesotrione (Tenacity herbicide), or Fenoxaprop-p-ethyl (Acclaim Extra) to kill crabgrass. These are ideal to use on Bermuda grass and various other cool and warm season grasses.
- Pick it out: If it’s young crabgrass, you should be able to pick it out of your lawn and discard it. If the plant is too mature, however, this method of crabgrass control isn’t likely to be effective. Mature crabgrass plants can sprinkle seeds onto your lawn as you’re removing them.
- Best crabgrass killer: Quinclorac and Acclaim Extra
- You can also find some decent ready-to-use products in big box stores and hardware stores to kill crabgrass. But these two products in particular will begin to show visible effects in as little as 48 hours.
How To Prevent and Control Crabgrass
Prevention is key to preventing and controlling crabgrass and keeping a healthy grass lawn. Here’s the best way how to do it:
- Tend to your lawn in the early spring and know when to apply crabgrass preventer: Before soil temperatures become favorable and crabgrass seeds germinate (55 degrees Fahrenheit) is when it’s most important to act. Apply the appropriate lawn fertilizer with crabgrass preventers (Step 1 of a 4 Step lawn care program), a pre emergent herbicide, or corn gluten meal to control crabgrass naturally. Such products will work to discourage crabgrass before the weed growth has a chance to thrive. If you don’t, your crabgrass problem will only be worse next year.
- Pro tip: follow up with a second pre emergent application in the early to mid summer. This will be your best bet towards a weed-free lawn all growing season.
- Feed your lawn regularly: One of the keys to preventing crabgrass growth is to grow healthy grass. A healthy thick lawn won’t just help prevent crabgrass from growing, but other grassy weeds as well. Make sure to fertilize accordingly and apply new grass seed to fill in any bare spots on your lawn every fall, especially any thin and bare spots where crabgrass actively grew.
- Mow properly: Crabgrass weeds thrive when growing low to the ground, and taller grass blades can become a key prevention strategy. for best results, make sure to mow at a higher height. This can help shade the soil below it and help with weed control. It can also be worth it to leave grass clippings on the lawn rather than bag them.
- Aerate your lawn: Compacted soil supports crabgrass growth (not to mention growth of other weeds). Regularly having your lawn aerated can help loosen up soil, help your lawn develop deeper roots and prevent crabgrass growth.
- Best crabgrass preventer: Prodiamine or Dithiopyr. For simple 4 step plans, Scott’s Step 1 is a great option in preventing crabgrass and other weeds.
When do I apply a crabgrass preventer?
It’s always better to prevent crabgrass than to administer crabgrass killers to control it after its seeds germinate in the summer months. Prevention is best carried out during the early spring months to ensure crabgrass stays away and desirable grass flourishes – before soil temps reach 55 degrees.
What is another (generic) name for Prodiamine?
Barricade by The Andersons uses Prodiamine and is often used synonymously.
What is another (generic) name for Dithiopyr?
Dimension 2EW by Dow AgroSciences uses Dithiopyr and is often used synonymously.
What is the generic name for Pendimethalin?
Pendulum and Scotts Halts are two of the most popular pre-emergent herbicides that contain pendimethalin.