Quackgrass

The coarse grass in the flower bed that grows back from white underground stems no matter what you pull. Quackgrass is identified by claw-like auricles at the leaf collar and sharp jointed rhizomes, and its defining trick is that cutting the rhizome wakes up every bud on it - which is why tilling multiplies it.

How to know it and how it moves: claw-like auricles clasping the stem, sharp white jointed rhizomes in the top two to eight inches, and a thin wheat-like seed spike. It travels as rhizome fragments in soil, mulch and nursery pots far more than it travels as seed.

You will not be planting this, so this is identification and movement.

The plant. An upright cool-season perennial grass, 1 to 3 feet if left alone, dull green to blue-green and noticeably coarser than the lawn around it. Blades are flat, tapering, often sparsely hairy on the upper surface and rough if you run a finger from tip to base. The lower leaf sheaths are usually hairy. The ligule — the little membrane where the blade leaves the stem — is very short.

The one feature to learn is at that same collar: auricles, two small, pale, claw-like or fingernail-like flaps that curl round and clasp the stem. Kentucky bluegrass, fine fescue and creeping bentgrass have none at all. Perennial ryegrass has small ones, and tall fescue has short blunt ones — but neither of those has rhizomes, so the two features together are conclusive.

Underground is the real plant. Rhizomes are whitish to straw-yellow, jointed, sheathed in brown papery scales, and sharply pointed — sharp enough to be found by piercing a potato or a carrot rather than by digging. They occupy the top two to eight inches of soil and spread aggressively in cool, moist weather. Every node carries a bud, held dormant by the rhizome tip; break the tip off and the buds all fire, which is the entire explanation for why cultivation multiplies this weed.

The seed head is a slender, erect spike, 3 to 8 inches, spikelets pressed flat against the stem in two alternating rows — a thin, sparse wheat or rye head, which is no accident: quackgrass is in the same tribe as wheat, barley and rye. Seed matters less than rhizome, but it stays viable in soil for a few years, so cutting heads before they shed is still worth a pass.

How it arrives. Overwhelmingly as rhizome fragments carried in bulk topsoil and fill, unscreened compost, straw and hay mulch, and container-grown nursery plants, plus whatever rides on tiller tines and boots from an infested part of the garden.

Lookalikes. Crabgrass is a warm-season annual that sprawls flat, roots at the stem nodes above ground, has no auricles and no rhizomes, and makes a finger-like seed head; it also appears months later in the season. Bermudagrass is warm-season, finer, grey-green, runs on visible above-ground stolons as well as rhizomes, goes tan and dormant in winter, and has a digitate seed head. Tall fescue is a coarse clump with a glossy strongly veined blade and a branched open panicle — and no rhizomes, so it stays a clump. Native wheatgrasses in the West are the serious confusion: western wheatgrass and its relatives are also rhizomatous with wheat-like spikes, but are markedly blue and stiff, and they belong there. Look before you treat.

Control, not care, and the method depends on where it is. In beds, a full-season opaque cover is the reliable answer, with fork-and-sift digging for small patches. In a cool-season lawn there is no selective fix at all - the honest options are spot-kill and reseed, or live with it.

Everything below follows from one rule: break a rhizome and you have planted it. Choose methods that exhaust the rhizome system or bury it in the dark, not methods that cut it up.

What fails. Rototilling is the classic disaster — it releases every dormant bud and distributes the cuttings evenly. Pulling snaps the shoot off the rhizome and prunes it. Mowing keeps it flowerless, which is worth something, but a mown stand simply runs sideways. Mulch alone, without a light-proof barrier, is pushed straight through.

Smothering is the method that suits this weed, because the rhizomes are shallow. Cut the top growth off, lay an opaque tarp or heavy overlapped cardboard, extend it two to three feet past the last visible shoot because the rhizome front runs ahead of the shoots, weight it thoroughly, and leave it down a full growing season. Late winter to the following autumn is the ideal span. Walk the perimeter every few weeks and cut or dig the runners escaping at the edges. One uninterrupted season clears most beds; an old, deep stand may want a second.

Digging is right for a small or new patch and for rescuing a planted bed. Work when the soil is moist and loose. Use a fork, never a spade — you want to lift and tease the rhizomes out in lengths, not slice them. Work outward from the shoots to find where the runners are heading, then get down and sift the loosened soil with your hands for pale fragments. Then keep coming back: check every two to three weeks for the rest of the season and pull each resprout as it appears, because a shoot removed before it makes surplus sugar is a net withdrawal from the rhizome.

Repeated shallow cultivation is the old field method and it does work, but only in genuinely hot, dry weather, where the point is to drag rhizomes to the surface and desiccate them. Repeat every two to three weeks through the dry spell. If the soil is moist, you are chopping and replanting, so the method flips from control to propagation with the weather — which is why it is a poor default for a home garden.

Competition is the follow-up that makes the rest stick. Cleared ground left bare gets recolonised from the edges, so plant it immediately and densely: a thick smother crop such as buckwheat in summer or winter rye in autumn, or close-spaced planting under mulch.

Herbicide, honestly. In a cool-season lawn — bluegrass, fescue, ryegrass — there is no selective answer. Quackgrass is a grass in a lawn of grasses, and nothing removes it without taking the turf with it. The real options are to spot-kill the patches and reseed, to renovate the whole area, or to accept it and mow. That is unwelcome, but it is the truth, and knowing it saves people a lot of money on products that cannot do the job. In beds, paths and non-crop ground, a non-selective systemic applied to actively growing quackgrass 6 to 8 inches tall does work, and it works far better in autumn, when the plant is loading its rhizomes, than in spring. Expect to repeat on the regrowth. Some products do remove cool-season grasses selectively from warm-season turf such as bermudagrass or zoysia, and the label will tell you. Whatever you use, choose a product whose label lists the site you are treating, follow that label including its replanting interval — the label is legally binding, not advice — and do not treat a bed you intend to sow next week.

And do not spread it. Bag rhizomes for the trash rather than composting them, do not move soil from a cleared patch to a clean one, clean tiller tines and boots, and check nursery root balls before you plant.

Why it exploded after you tilled, how to tell it from crabgrass and bermudagrass, what to do about it in a lawn (the honest answer is uncomfortable), why it pierced your potatoes, and how long a tarp really has to stay down.

“I tilled the bed and now it is everywhere.” The signature quackgrass mistake. Each rhizome tip suppresses the buds behind it; cutting the rhizome releases all of them at once, and the tiller then spaces the cuttings out neatly. Mark quackgrass ground and keep machinery off it.

“Is this crabgrass?” Almost certainly not, if it is spring and the grass is upright and coarse. Crabgrass is a warm-season annual: it germinates as soil warms, sprawls flat, roots where the stems touch soil, has no auricles and no underground runners, and makes a finger-like seed head. Quackgrass is up and growing in cool weather, stands upright, has claw-like auricles clasping the stem, runs on white underground rhizomes, and makes a thin wheat-like spike. They also need opposite treatment, so the distinction is not academic.

“Is this bermudagrass?” Bermudagrass is warm-season and finer, runs on visible above-ground stolons as well as rhizomes, is grey-green, goes tan and dormant in winter, and has a seed head of three to seven finger-like spikes. Quackgrass is green and growing when bermudagrass is dormant, which is the fastest test of all.

“What do I do about it in my lawn?” The honest answer is that no selective product removes quackgrass from a cool-season lawn without killing the lawn. Your choices are to spot-kill the patches and reseed, to renovate the area, or to mow it and let it be. Mowing high and keeping the turf dense makes it less obvious and slows its spread, but it will not remove it.

“Something pierced my potatoes.” Quackgrass rhizomes have hard sharp tips and will grow straight through a potato tuber, a carrot or a parsnip — and through the roots of young trees and perennials. Damaged tubers rot in storage, so grade them out. A bed intended for root crops is a bed worth clearing properly first.

“It came back after a whole season under a tarp.” Usually from the edges. The rhizome front runs a foot or two ahead of the shoots you can see, so the cover has to extend two to three feet past the visible patch, be light-proof, be weighted at every edge, and be patrolled. Then a second season finishes what is left.

“I never had it until I brought soil in.” That is the standard route: bulk topsoil, fill, unscreened compost, straw or hay mulch, and container nursery stock all carry rhizome fragments. Stage deliveries on a tarp and check root balls before planting.

“Does it hurt my crops beyond competing?” Yes, in two ways. It is allelopathic to some crops, including corn and several vegetables, so the effect is more than shading. And it is a green bridge for cereal problems — wheat curl mite and the wheat streak mosaic it carries, take-all, and cereal nematodes — as well as shelter for wireworms and slugs.

“How long is this going to take?” One full season under an unbroken cover, or two to three years by digging and repeated removal. What it will not be is a weekend.

A cool-season grass hardy to roughly zone 3 and dominant across the northern two-thirds of the country. Heat and drought check it, not cold - so it is a spring and autumn problem in the North and largely a non-problem in the Deep South, where bermudagrass takes its place.

Quackgrass is a cool-season grass, and that single fact explains its map and its calendar. It is hardy to roughly zone 3 — about -40°F — and it is common through the northern two-thirds of North America, thinning out markedly as summers get long and hot.

North and Northeast, zones 3 to 5. Its heartland. It grows in the cool wet weeks of spring and again from late summer until the ground freezes, and it is one of the most troublesome perennial weeds of gardens and field crops in the region. Winter does nothing whatsoever to it; the rhizomes simply wait.

Temperate zones 6 to 7. Very common, with the classic two-flush pattern: an aggressive spring surge, a genuine slowdown in midsummer heat, and a strong autumn regrowth that is the best moment of the year to act against it.

South, zones 8 and warmer. Much less of a problem, and often absent. Long hot summers exhaust it, and its ecological role is filled by warm-season runners such as bermudagrass — a different weed with a different calendar and different controls, so do not carry quackgrass advice south with you.

West. Widespread in irrigated and higher-elevation ground and in the Pacific Northwest. The regional caution here is identification: several native rhizomatous wheatgrasses look broadly similar and belong in the landscape, so confirm the auricles and check the leaf colour before treating a stand in open country.

Two practical consequences hold everywhere it grows. Its growth season is the cool ends of the year, so time cutting, digging and any systemic treatment to spring and especially autumn, not to midsummer. And heat and drought are the only weather that hurts it, which is exactly why dragging rhizomes to the surface works in a dry August and backfires in a wet one.

One of the oldest weeds of European agriculture, in North America since the colonial period, and a wheat relative close enough to matter to plant breeders. Its rhizomes fed livestock in hard winters and were dried as the 'couch grass root' of nineteenth-century pharmacy - and dogs still eat it, which is where 'dog grass' comes from.

Quackgrass has followed the plough for as long as there has been one. It is native to Europe and temperate Asia, it appears in European farming literature for centuries under names like twitch, quitch and couch, and it crossed the Atlantic early with colonial agriculture — in ballast, in hay, in seed grain and in the soil around imported plants. By the nineteenth century it was already regarded as one of the worst perennial weeds of northern American farms, and mechanised tillage, which cuts and distributes rhizomes at scale, did nothing to help.

It is also, botanically, a near relation of the crops it infests. Quackgrass sits in the same tribe as wheat, barley and rye, which is why its seed head looks like a thin head of wheat — and why wild relatives in this group have long interested cereal breeders as sources of disease resistance and perenniality.

Its uses are modest but real, and they explain the names. The rhizomes are starchy: they were dug as emergency fodder in hard winters, ground as a famine flour in parts of Europe, and dried and sold in pharmacy as couch grass root, a traditional soothing and diuretic tea that appears in nineteenth- and twentieth-century pharmacopoeias. Dog grass comes from the habit dogs and cats have of chewing coarse grass, quackgrass among it, and inducing a good vomit — the same behaviour sold today in a pot as pet grass.

None of that is a reason to keep it. It is worth knowing chiefly because it puts the plant in proportion: quackgrass is not sinister, it is not poisonous, and it does not need to be feared. It just needs to be removed by a method that does not chop it up.