Crabgrass vs. Quackgrass – Differences and Idenitification

When it comes to keeping and maintain a beautiful green lawn, the biggest obstacle you’ll face is grassy weeds that invade your lawn and mess up the overall look of your lawn. Crabgrass and quackgrass may look similar, but they’re very different.

One of the main differences between the two grass weeds is that crabgrass is a warm-season annual while quackgrass is a cold season perennial. They have very different ways of spreading and you use different methods to eradicate them from your lawn. Although they both can’t thrive in thickly shaded lawns, crabgrass forms shallow roots with a crab-like structure while quackgrass uses rhizomes that grow horizontally and deep in the soil. 

Crabgrass

Crabgrass is a warm-season annual grass that thrives in hot, dry weather and is mostly found on your lawn during spring and early summer.

Crabgrass sprouts annually from the seeds dropped the previous season and the crabgrass seeds germinate when it’s warm which is in mid to late spring through to early summer.

Two common crabgrass species include the small or smooth crabgrass and the large or hairy crabgrass.

The smooth crabgrass is the smaller of the two and has dull green leaves that are a bit hairy at the base and are usually less than 15 inches high with each leaf being about 1-4 inches long.

The large crabgrass forms a thick mat of growth with pale blue-green leaves and grows up to 3 feet with each leaf being2-6 inches long. The large crabgrass can spread quickly through tillering or through sprouts found at the base of the plant that quickly increases the width of the weed clump.

Both species are summer annuals that die when it’s cold and produce lots of seeds that remain in the soil for years ready to grow. 

To understand how to identify crabgrass watch the video below

How it spreads

Crabgrass spreads by seed and this limits its way of spreading, so if you stop the seeds from germinating, you stop the plant from invading your lawn.

However, you have to get rid of this grass weed at the right time to prevent germination.

Each crabgrass produces lots of seeds and although the first frost kills the plant, the seeds stay dormant through winter and begin to grow once the soil arms up. 

Crabgrass prevention

Water your lawn before crabgrass season

If your lawn is actively growing and has plenty of moisture, it will be difficult for crabgrass to establish itself on your lawn.

Avoid watering your lawn in late spring and early summer which is about the same time crabgrass starts to sprout. When your lawn is dry and the blades are thin, it takes a few days or weeks to recuperate and start growing again after watering it.

This gives time for the crabgrass seeds to absorb water and sprout.

Seed early and late

A thick lawn keeps crabgrass away, but a thin and bare lawn invites crabgrass. Some grasses spread rapidly with the help of surface and underground runners filling up bare spots, while others don’t spread much and need more grass to thicken the lawn.

Before the soil warms up for crabgrass to sprout, plant grass seeds a few weeks before, and after the crabgrass dies, reseed the thin areas in your lawn.

Mow high

Crabgrass loves sunlight and warm soil, but not shady areas. A thick tall lawn will prevent sunlight from reaching the soil and keep the soil cool.

If you mow too short, you allow the sun to warm up the soil faster and you also weaken your lawn which makes it easy for crabgrass to grow.

Uproot the weed

If your lawn is already infested with crabgrass, the best way to get rid of it is to uproot it, especially in the summer when the clumps have spread over your lawn.

Grab the lowest part of the stem and pull it out. Dispose of it carefully to avoid spreading the seeds.

You can use these best gloves for pulling weeds effieciently.

Apply a weed killer

If you have a large lawn, it will be difficult to uproot every weed on your lawn so the best way is to use a post-emergent herbicide that will kill grassy weeds after germination.

You can also use a pre-emergent to prevent the seeds from germinating.

Quackgrass

Quackgrass is a perennial grass that reproduces through seed and creeping rhizomes. It forms in patches and has a coarse fibrous root system with flat dull green to light blue-green blades.

The seed spikes grow from 3-8 inches and appear in July and produce about 25 seeds that can remain in the soil for 5 years waiting to germinate.

Quackgrass produces many rhizomes which makes it difficult to dig it out that’s why it’s important to eliminate it before it reaches this stage.

Quackgrass prevention

This weed grass is very difficult to get rid of because its root system strengthens a lot during winter and when it gets warmer it starts to grow and spread rapidly all over your lawn.

It thrives in taller lawns and mowing your grass 3 inches will naturally help to get rid of quackgrass but slowly.

Mechanical control

If quackgrass hasn’t spread over your entire lawn, you can try pulling it out. You can also try mowing, cultivating, plowing, or disking if your lawn isn’t already established.

Mulching

You can use smothering methods to help get rid of both crabgrass and quackgrass. Since they both don’t thrive in the shade, you can spread a 2-3 inch layer of mulch to prevent the seeds from sprouting.

Quackgrass rhizomes spread underneath the surface and can shoot from a tiny spot on your lawn.

Apply a non-selective herbicide

It’s harder to get rid of quackgrass than crabgrass because there are specific herbicides that target crabgrass, but there’s no specific weed killer for eliminating quackgrass.

This means you can only use a non-selective herbicide like Roundup to kill quackgrass.

Differences Between Crabgrass and Quackgrass

Root system

Crabgrass is a flat-lying grass that has finger-like roots that spread outward from a clump.

Its root system is completely under the soil and only stems from one source. However, Quackgrass is a flat-bladed grass that spreads quickly using rhizomes that creep across your lawn establishing connector roots in the soil to obtain nutrients.

Type of weed grass type

Crabgrass is a warm-season annual grass that thrives in warm temperatures so you’ll often find it growing at the edge of your lawn where the soil meets the pavement. It grows every year during summer and dies in winter.

Quackgrass on the other hand is a cold-season perennial grass that lives a year to year growing back every spring from a winter-hardy root system. 

Leaf-blades

Both crabgrass and Quackgrass have wide leaf blades, but Quackgrass has clasping auricles which you can easily see where the grass blade wraps wound the lower stem.

Crabgrass doesn’t have these auricles.

Weed control

You can prevent crabgrass seeds from germinating by applying a crabgrass herbicide in your soil before the temperatures reach 60 degrees.

You can also use a post-emergent crabgrass herbicide if the pre-emergent didn’t work.

However, you can only use products like Roundup after it’s actively growing. No product can selectively kill Quackgrass.

How to control different weed grasses

Weed species

Lawn management control

Dandelion

Uproot by hand, improve lawn management practices

Plantain

Reduce irrigation, improve lawn care, aerate

Creeping woodsorrel

Uproot before it spreads

Nutsedge

Remove before it spreads, reduce irrigation

Common knotweed

Aerate

California burclover

Remove plant and fertilize

Final thoughts

You can easily get confused by crabgrass and quackgrass, but they both have different methods of controlling them.

Also read

How to Kill Crabgrass with Baking Soda – Complete Step Guide

Dallisgrass vs Crabgrass – Differences and Identification

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