Quack Grass


Quack Grass

by Rob Sproule, May 31, 2013

Normally these articles afford me the happy task of reassuring people that intimidating gardening tasks are easier than they think.   Today, unfortunately, it’s my job to tell you that Quackgrass is just as bad as you think it is.

Known also as couch grass, twitch grass, and, most aptly, devil’s grass, Quackgrass (Agropyron repens) is a scourge of both farms and gardens in every part of Canada.   It’s listed as one of our top 3 most vile weeds and is estimated to infect over 50% of farmland in the country.

Quackgrass’s Latin name (Agropyron repens), translates to “sudden field of fire”, in rueful recognition of it’s ability to quickly infest large swaths of earth.   Native to Europe and Western Asia, it’s thought to have caught a ride across the pod centuries ago with cereal crops.


Devil’s Grass 101
Quackgrass spreads by both seed and rhizome.   Each mature plant will yield about 25 seeds, which stay menacingly viable for years once on the ground.   It’s vital to pull Quackgrass before it seeds.

The rhizomes sound like some insidious invention cooked up by a comic book super villain. The white, fleshy tubers, somewhat resembling sprouts, grow rapidly until they establish a thick mat a few inches under the soil surface.

When I say they grow rapidly, I’m not kidding! In the cool spring months, when it’s most active, it’s rhizomes can sprint up to 2.5 cm per day.   New grass blades can emerge from any point on the rhizome.

The rhizomes grow from any and every tip.   If you break one in half, it suddenly has 2 new tips to grow and spread from.   The tips are strong enough to push through potato tubers and over time, even asphalt.


It’s a common mistake to roto-till the rhizomes into little pieces.   While this may work on other weeds, Quackgrass is a super-villain weed and each shredded bit of rhizome will grow into a whole new network of frustration (like a curse from a Harry Potter movie).

If there are no other plants in the area you need to control, all you’ll need is a little determination.   When the soil is moist, carefully dig up the soil and remove the white, fleshy rhizomes by hand.   Take care not to break them.

Once the rhizomes have been removed, lay down thick layer of wood mulch, with an optional layer of cardboard underneath, to smother any new growth.   Keep a close eye around the edges of the mulch, as the rhizomes will creep – quickly- to where they sense sunlight.

It’s important to pull new green growth as soon as possible.   The rhizomes feed on nutrients derived from photosynthesis, and if deprived of those they will eventually starve.   On the other hand, a patch of Quackgrass left unseen and/or un-pulled will strengthen the rhizomes.

As a last resort, spray Round-Up on an afternoon hot enough that the blades will pull the poison thirstily into their rhizomes.   Don’t spray if it’s windy or if you have pets and/or children using your yard.

If Quackgrass has infested your lawn, shrubs, or perennial beds, settle in for a war of attrition.   The rhizomes wrap around other plants’ roots making wide-scale, effective excavation impossible.

Stay diligent and keep pulling.   Stay diligent and keep pulling. Laying a thick layer of wood mulch around your existing plants will slow down emerging blades, but take care that it’s not so thick around your plants’ stems that they rot from never drying out.

As Quackgrass isn’t a broadleaf weed, it’s immune to selective herbicides like Killex, which are designed to not kill lawns. If you don’t want to kill all your other plants as well, your only chemical option is to tediously paint a glyphosphate herbicide (ex. Round-Up) on the blades themselves.


Read through our Growing Guides for tips to enrich your garden! 

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