What Is Quackgrass and How Do I Control It?

Quackgrass can be tough to kill, thanks to its extensive root system and underground stems.

Even if you've never heard of quackgrass, chances are you've seen it. This perennial grassy weed has been plaguing gardeners in the U.S. for roughly 200 years and has, fittingly, been called everything from devil's grass to witch's grass. Read on to find out if quackgrass is the villainous weed that has invaded your landscape —then discover how to vanquish it for good.

Jump down to how to kill quackgrass.

What You Need to Know About Quackgrass

  • Cold-season perennial grassy weed
  • Blue-green blades with rough texture (can appear smooth or hairy)
  • Stems will have a little collar wrapped around them where the leaf connects (this is called an auricle)
  • Seed heads look similar to those of wheat or ryegrass
  • Extensive root system can grow 6 to 8 feet deep
  • Spread via seeds and aggressive underground stems, called rhizomes, that can create a 6-foot wide network from a single plant
  • Can grow up to 4 feet tall

Identifying Quackgrass

Although quackgrass is often mistaken for crabgrass, this weedy nuisance is truly its own beast. Like crabgrass, it’s lime green and has a thin, flat, coarse leaf blade, but it can be more challenging to control because its roots run deeper into the soil.

Quackgrass can grow up to 4 feet tall and produce up to 25 seeds per plant that can live for up to 5 years in the soil. In other words, if you don’t take action, you’ll be battling this plant for many years to come. Quackgrass also sprouts from underground stems (called rhizomes) that creep and spread, helping the plant to spread aggressively. Left unchecked, a single quackgrass plant can produce an extensive root system with rhizomes that can spread up to 5 feet in a single growing season.

How to Kill Quackgrass

  1. Just say “no” to hand-pulling.

    Don’t waste your time hand-pulling quackgrass. Even the tiniest bit of rhizome (underground stem) left behind in the soil will simply produce more of this tenacious weed.

  2. Kill it with Roundup® Weed & Grass Killer products.

    The quickest way to get rid of quackgrass in your garden and landscape beds is by spraying it with Roundup® Ready-To-Use Weed & Grass Killer III. Be prepared, though: Thanks to this plant’s hardy nature and extensive root system, it may require a second application to wipe it out completely.

  3. Smother it.

    Another way to kill quackgrass is to smother it with mulch. Adding a 2-3 inch layer of wood chips or laying down landscape fabric or black plastic can help prevent quackgrass from popping up in your garden beds. However, the rhizomes of quackgrass may continue to creep along until they finally find a spot where they can send up a shoot.

If you don't have quackgrass or have just a very small amount of it, do whatever you can to prevent it from making inroads in your yard. It’s crucial to stop this weed early, before it has a chance to mature and cast its evil spell over your yard.