How do I control quackgrass?

April 20, 2006 7:40 AM

What to do about quackgrass.

I've got a patch of quackgrass in my yard, and no prevention-type application seems to control it. I try putting something down earlier every year (to try to stop the quackgrass before it begins to grow), but nothing has worked, and it is slowly gaining space in my yard. Does anyone have any suggestions on how to control this nuisance?

posted by Todd Lokken to Home & Garden (11 answers total)

have you talked to your local nurseries about the conditions in your area and what works best? from what I know, it can be a very region-specific thing.
posted by kcm at 8:48 AM on April 20, 2006

If by prevention you mean a pre-emergent herbicide (e.g. Preen) then you're wasting your time. Pre-emergent herbicides are germination inhibitors; they work on crabgrass and other annual weeds because those need to restart every year from seed. Quackgrass, however, is a perennial, just like lawngrass, and once present doesn't need seed germination to keep going.
posted by TimeFactor at 9:04 AM on April 20, 2006

If you only have a patch, why not dig it out and re-sod?
Better than paying for 2,4-D type chemicals and applying them several times.
posted by weapons-grade pandemonium at 9:06 AM on April 20, 2006

2,4-D won't work on quackgrass either. It's a selective herbicide that only works on broad-leaved plants (like dandelions) and has no effect on grasses, like lawn grass and, unfortunately, quackgrass.
posted by TimeFactor at 9:10 AM on April 20, 2006

I would spray the area with Roundup. It may take a couple of applications. Then rake up the dead quackgrass, lay down a little topsoil and re-seed. It is very important to keep the new seed watered until it gets established. If you cover the new seeds with some straw mulch it will keep it from drying out.
posted by Ostara at 9:15 AM on April 20, 2006

Response by poster: Time...your comments are interesting, especially since the herbicides I've tried to use say they prevent quackgrass. Do you think they may be adding that in as wishful thinking?
posted by Todd Lokken at 9:16 AM on April 20, 2006

Prevention-type herbicides will prevent quackgrass seed from germinating but 1) that isn't how quackgrass is usually spread (it spreads mostly from root systems) and 2) won't help you if it's already established.

Quackgrass can have root systems that spread for many feet and can go three feet down. To get established quackgrass out of a lawn (which is what I assume you mean by yard) then you'll need to completely kill the area and start over. Just diggin it out won't do it. You can kill the area by putting down an opaque barrier like black plastic for a few weeks then sodding or reseeding or killing the entire area with a general purpose herbicide like glyphosate (e.g. Roundup) as Ostara recommends. It'll likely take more than one application to kill quackgrass though. Again, sod or reseed.

Or just live with the quackgrass. Keeping your regular grass healthy will help give it a competitive advantage over the quackgrass. Make sure it gets enough water, fertilize, lime as appropriate, cut it to the right height (3" for most grasses).
posted by TimeFactor at 9:20 AM on April 20, 2006

I don't know where you live, Todd, since it isn't in your profile, but if you life in the US, your county extension agent can give you free advice on how to deal with your quackgrass. And how to keep your lawn all healthy, so it can fight off the evil invader.
posted by QIbHom at 9:52 AM on April 20, 2006

Response by poster: Actually, it is somewhat odd...the quackgrass shows up as an eyesore in the early spring, so it stands out. Once the rains come, the regular kentucky bluegrass tends to overtake it.
posted by Todd Lokken at 9:56 AM on April 20, 2006

Response by poster: In case anyone is reading, here is a decent link:

http://gardenline.usask.ca/yards/quackgra.html
posted by Todd Lokken at 7:30 AM on April 21, 2006

Your link is mostly in agreement with what we've said here. I'd be careful about the recommendation to mow low, though. Cutting the grass very short is a little like chemotherapy: you're hoping to kill the bad stuff (quackgrass) before you kill the good stuff (lawn grass). Too-close mowing weakens your lawn and makes it more susceptible to stress (like drought and foot traffic) and to other weeds. If your lawn isn't very healthy to begin with you run the risk of mowing it into oblivion along with the quackgrass.
posted by TimeFactor at 10:14 AM on April 21, 2006