Quack grass, also known as couch grass, twitch, quitch, quick grass, scutch, and witch grass, is one of the hardest weeds to control in lawns and gardens. It is also a problem for the agricultural world, as it can reduce crop yields, contaminate grain seeds and straw, and be spread to new fields on tilling equipment and in manure spreaders. Its nightmarish ability to reproduce via root stems called rhizomes makes cultivation of mature plants with a rototiller a very bad idea. Rototilling will chop the roots up into smaller bits, and each piece has the potential to become a new plant. While control is difficult, it isn’t impossible. The agricultural world has developed many herbicides that can effectively kill quack grass if properly applied, and there are some cultural and mechanical options as well that are more appropriate for home use.
Identification of Quack grass
Quack grass (Elytrigia repens) is a perennial grass weed that can propagate via seeds and long, whitish-yellow rhizomes that spread outward under the surface of the ground. It can grow to four feet in height; its seed head ranges from three to eight inches and can contain up to 25 seeds.
Best Methods of Controlling Quack Grass
Prevent quack grass, if you can. If your property is surrounded by areas of quack grass or other weeds, it is almost inevitable that they will end up in your lawn or garden eventually, either by seeds blowing in on the wind, being pooped out by birds, or by the gradual inward creep of the rhizomes. There is little you can do about the wind or birds, short of a giant plastic dome, but you can try to maintain a border zone free from those weeds. You can also install buried plastic edging or plan your garden as a raised bed to prevent a rhizome invasion.
Use mulches to kill quack grass. Mulches are just layers of some sort of material, which, when placed on the soil surface, prevent plant growth and also retain moisture for the benefit of your garden plants. They can be organic, as in compost, grass clippings, straw, or wood chips. They can also be man-made like plastic sheeting (like this sold at Amazon), landscape fabric, newspaper, and cardboard. Some are more degradable than others; it depends on how permanent you need it to be. Be aware that quack grass rhizomes can grow under mulch and extend out to the edge. So keep your eye out for that.
Encourage healthy growth of lawn grass and garden plants. As with any crop, it is important that your desirable plant out competes the weeds in the area. If you have a well-fertilized, aerated, properly mowed lawn, most weeds won’t stand a chance. The same goes in a garden. If you can give your tomatoes, squash, corn, flowers, and other plants a head start with weeding or mulch, they can usually hold their own, or, at the very least, keep the weed stunted enough that you can remove it before it causes any harm. Weeds can leach away necessary water and nutrients if left untended.
Manual removal is always an option. This is certainly the least-fun method for controlling quack grass. Resist the temptation to chop it up into little bits with a rototiller or you will be creating a headache for yourself. Many of those little bits will come back as new plants. You’re better off sifting through sections of your soil with a gardening fork, picking out rhizomes in early spring before they start growing. You may have to do this several times, but it will be worth it, eventually. When you see new quack grass coming up from seeds, be sure to remove before it is 2‒3 months old because that’s when it will start sending out rhizomes of its own and producing seeds.
Use selective herbicides in gardens. Get it while it is young: that is the advice you will always hear. If the quack grass is a new growth from seeds, you have a window of opportunity that extends out 2‒3 months in which it doesn’t grow any rhizomes. During that period it is susceptible to grass-killing herbicides. After that period, it could still survive via dormant rhizome buds. The nice thing about grass killers, like Ortho Grass-B-Gon, is that you can use it in your gardens fairly safely and it won’t harm your garden plants too much, unless they are grass family plants themselves, such as grains and alliums. In your lawn you need to be more careful, try MSMA-based weedy grass killers.
Apply a non-selective herbicide to growing plants. This is really the salt-the-earth, leave nothing standing option. Glyphosate herbicides like Roundup will kill just about everything. However, it needs to be applied properly. In a garden situation, you might want to consider painting on the herbicide, being careful not to spray or drip on surrounding plants. Try to plan to use it on a calm windless day when there is no threat of rain. The way this stuff works is dependent upon the plant being in a growing phase. So it needs to be applied directly to green living plant tissue. After a few weeks, check back and apply again if new rhizome shoots have come back.
Chemical Quack Grass Control
Kill everything. If you are looking to kill a patch of established quack grass plants and you don’t mind killing everything around it, you should use a glyphosate non-selective herbicide like Roundup. You will need to apply multiple times, as the herbicide doesn’t affect the rhizome buds and they will sprout up again. You can pair application with a nitrogen fertilizer to trigger the buds to sprout before the herbicide wears off. Wait a couple weeks before tilling up the area or the rhizomes will still be viable.
Garden. If you have a few patches of quack grass that is surrounded by non-grass‒type plants (dicot vs. monocot), you can use Ortho Grass-B-Gon, which contains a chemical called Fluazifop-P-Butyl. Warning: This chemical will also kill plants like corn, lilies, and onions, so take care. Again, multiple applications may be necessary due to rhizome buds.
Lawn. Killing grassy weeds in your lawn poses a problem because they are all essentially grasses. There are some products out there by Acme and Greenlight that contain a chemical called MSMA (monosodium methyl arsenate) and are meant to target grassy weeds like crabgrass and quack grass.
Best Natural Quack Grass Control Methods
Grazing and plowing. If you have access to a herd of goats or any ruminant, fence them in the area of quack grass you wish to remove in the late summer. They will repeatedly eat the leaves, which will weaken the energy storage ability of the plant. Dig up the rhizomes at this point with a plow or garden fork. Allow them to dry and die in the heat of the sun or freeze over winter as they will be unprotected.
Corn gluten and other preemergents. After you have killed the quack grass from the previous year and removed as many rhizomes as possible, you will still have to deal with seeds, which can sit in the ground dormant for up to five years. Corn gluten is a natural preemergent that prevents seed growth. There are chemicals that do the same thing if you can’t find corn gluten. However, trust us…you can get a bag of Concern Weed Prevention Plus Corn Gluten Meal at Amazon.
Plant cover crops to crowd out quack grass. Plant cover crops in early spring, before quack grass rhizomes and seeds have a chance to send up new shoots. Do this in areas that you might want to use in future gardens. They will serve as an organic mulch for the area and prevent weed growth. Be sure to kill the crop, or harvest before they set seeds. Some good cover crops are oats, rye, wheat, clover, sorghum, and buckwheat.