Dallisgrass vs Crabgrass: Which Weed Is In My Lawn?

Do you know which weed is choking up your turf? The worst lawn offenders are two grassy weeds, Dallisgrass and Crabgrass. These weeds sneak in unnoticed and become tough to control. They take away the overall beauty of your well-manicured lawn, almost threatening the turfgrass. But is dallisgrass and Crabgrass the same?

Herein, I will explain how to identify each of the weeds and the best approach to controlling them without harming your lawn. Read on as I compare dallisgrass vs Crabgrass.

How to Distinguish Them

Dallisgrass and Crabgrass share some distinct similarities that make identification quite difficult. They are both clumping grasses and may look similar, but a few key differences will help you tell one from the other.

Dallisgrass has a large seed head with minute black spots which grow off the stems at multiple points. In contrast, Crabgrass has a small, fine seed head that shoots from the center of the clump to resemble a crab’s legs. Crabgrass leaves are long, wide, and slightly rolled in the bud.

You can also tell dallisgrass from Crabgrass by its appearance. Whereas Crabgrass grows outward in a star-shaped pattern, dallisgrass tends to grow taller and fuller. If you are still struggling to differentiate them, the following distinctive features will help you tell them apart.

Leaf Morphology

Dallisgrass leaves are dark green and coarsely-textured, with a dull surface. On the other hand, crabgrass leaves have a lighter shade of green and could have a smooth or rough texture, depending on the species.

Crabgrass leaf surfaces are also shinier than dallisgrass. You can easily identify Crabgrass by its broad leaves, which cover expansive areas within a short time. They are about ¼ centimeters wide, whereas dallisgrass leaves are narrower, at about ⅛ centimeters.

Growth Habit

Dallisgrass forms circular clumps on lawns. Reaching up to 5 feet, the shoots of dallisgrass are thicker and stiffer. They also have underground rhizomes with a wide diameter, from which new shoots develop and proliferate to form the clumps.

Contrastingly, Crabgrass forms a reminiscent star of shoots resembling a crab’s legs. The numerous branches of this weed emerge from its sides to form a thick star-like mat of weed. They also grow lower to the ground compared with dallisgrass.

Life Cycle

Crabgrass is an annual summer weed, whereas dallisgrass is perennial. After summer each year, you will notice dallisgrass growing back on the lawn from the same root system. The underground rhizomes grow and spread quickly, sending new shoots to rise above the ground in early summer.

On the other hand, the lifespan of Crabgrass doesn’t exceed one year. Its seeds start germinating in late spring or, when the conditions are favorable enough, in early summer. It thrives throughout the summer, reproduces, and dies within the same year. Winds, animals, and birds spread the seeds, which establish the following season.

Where They Grow

Crabgrass and dallisgrass can grow in the same soil, but both may not thrive so well. Dallisgrass thrives in clay and sandy soils.

They grow more rapidly in nitrogen-rich soil, twice as much as regular turf grass, creating an ugly sight in lawns. They also invade all types of turf grass and can be hard to control because they spread so quickly.

On the other hand, Crabgrass flourishes in clay and loam. They spring off the bare spots of any lawn and proliferate, undermining the growth of turf surrounding it.

Dallisgrass vs Crabgrass: Similarities

These two lawn weeds are similar in the following ways.

  • Both weeds germinate early in the spring and proliferate once they are established.
  • Both weeds mainly reproduce through seeds, but there’s a possibility of generating new roots from underground rhizomes.
  • Both Crabgrass and dallisgrass discourage a lawn from thriving.
  • Both weeds thrive better during dry weather and are sensitive to frost that comes with cooler climates.

Effects of Dallisgrass and Crabgrass in Lawns

Dallisgrass and Crabgrass are a big nuisance. They can be tall and bushy, outgrowing regular lawn grass. Dallisgrass creates an unsightly clump that, besides causing an uneven appearance, could present a hazard in playgrounds. They also discourage the establishment of new turfgrass on a lawn.

Crabgrass, on the other hand, thrives in the spring and may threaten the entire lawn. Being an ‘opportunistic’ plant, it can crowd out turf grasses. Crabgrass also creates an uglier sight when hard frost season comes about. It dies, turns brown, and leaves several bare spots on your lawn.

How To Get Rid of Crabgrass

Crabgrass vs dallisgrass, how do you eliminate each weed? The best time for applying pre-emergence herbicides for Crabgrass is after your second regular mowing in spring. Use a lawn spreader to apply pre-emergents around driveways, path walks, and alongside the neighbor’s crabgrass-infested yard.

Use a fertilizer with pre-emergent herbicide added to it. You should do this just before it rains to facilitate absorption into the soil. An example of a fertilizer that comes pre-mixed with a crabgrass preventer is Greenview Fairway Formula Spring Fertilizer + Crabgrass Preventer.

Identify and uproot Crabgrass early. Crabgrass identification and removal in its early stages are vital because they’ll only leave a small hole in your tuff. Young crabgrass plants are light green and are easily distinguishable once you take a keen look at your lawn.

Inspect your yard carefully, looking for immature crabgrass seed heads. They start showing up during or immediately after winter and are green, slender, and still folded up against the leaves. 

Although they are difficult to remove, you must pull them out cautiously. If the seed heads have already spread out like a fork, there’s no need to dig them out as you might end up spreading the seeds.

Spray stubborn patches of Crabgrass with post-emergent herbicides. They are most effective if applied during the day when moisture is the least, and the wind is low. Keep an eye on the treated area. 

If the weather is parched, you might need to irrigate the lawn after two days to aid absorption. If the Crabgrass doesn’t die after two weeks, retreatment is advised.

How To Get Rid of Dallisgrass

To manage dallisgrass perfectly, you must prevent new plants from establishing at the start of summer. The best control strategy is digging them out before they form rhizomes. You may also dig out mature weeds, but they will grow back if the rhizomes are left behind.

It’s essential to prevent the growth of dallisgrass in professionally managed turfgrass areas. Incorporate chemical control measures if dallisgrass takes over your lawn.

Chemical Control for Established Dallisgrass

Chemicals for controlling established plants are known as post-emergent herbicides. They can either be selective or non-selective.

Foramsulfuron (Revolver), Weed-Hoe, and Weed-B-Gon Weed Killer for Lawns are some of the best post-emergent herbicides in the market for controlling dallisgrass.

Leave your lawn unmowed for two weeks before the first application. Doing this creates the maximum surface area with which the chemicals will come into contact with dallisgrass. The weather should also be fair because applying post-emergents when it’s too hot may injure the turfgrass.

Since herbicides have different chemical properties and instructions for use, ensure you read every label comprehensively before using them. Retreatment after two weeks may be required in case the weed isn’t entirely killed.

One of the most common mistakes homeowners make when controlling dallisgrass is to use glyphosate (Roundup). As a non-selective herbicide, glyphosate kills dallisgrass and turfgrass, leaving the whole lawn dry and bare.

Chemicals used to control dallisgrass before germinating are referred to as pre-emergent herbicides. They include:

  • Benefin + oryzalin
  • DCPA
  • Prodiamine
  • Oryzalin
  • Dithiopyr
  • Bensulide

Pre-emergent herbicides work best when they are applied in early spring or late winter – provided the seeds are yet to germinate.

Once you apply pre-emergent herbicides when the weed has grown beyond the seed stage, the chemicals are as good as wasted. To be effective, pre-emergent herbicides require you to irrigate about ½ inch of water after application. Consult the label for application details first.


You certainly don’t want to stare at weeds taking over your lawn, not particularly dallisgrass or Crabgrass. We hope the above dallisgrass vs crabgrass guide will help you distinguish these two types of weed. You can be assured of perfect, healthy lawns if you get rid of them.

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