Dallisgrass vs Crabgrass: How to Tell The Difference

Written By: Todd Thomasson

All you want is a nice, green lawn. It’s really not too much to ask for at your Northern Virginia home.

But weeds can certainly get in the way.

They are leggy and tall, standing out from your regular grass – and not in a good way. They seem determined to ruin the look of your healthy, well-kept lawn, detracting from its curb appeal-building appearance and making you want to hide from the neighbors in embarrassment. 

And when the weeds that are cropping up in your lawn look like grass, this can almost be worse. It’s like from afar you can see a discoloration difference and up close you can see a difference in grass blade thickness and texture, but you don’t always know what the problem is and how to fix it. And, before you know it, grassy weeds seem to have taken over your good grass. 

In Northern Virginia lawns, two weeds like this that can cause the most problems are dallisgrass and crabgrass. Both of these grassy weeds can sneak into your lawn, looking like grass, and once they are in, they can be tough to control and eliminate. And when they appear, you’re left wondering, “Which weed is this – dallisgrass or crabgrass?” 

Because knowing the weed you’re fighting is important to proper weed control, let’s talk about how to tell the difference between dallisgrass and crabgrass so you can better identify and get a handle on your lawn weed problem so you can enjoy your lawn again.

Let’s Start With The Major Differences Between Dallisgrass vs. Crabgrass

We know grassy weeds can be especially annoying when they show up in your Northern Virginia lawn. You just want them to go away; we all do. 

Read The Ultimate Guide to Controlling Lawn Weeds
And even though you don’t want to get to know these weeds any better, understanding them and their differences can really make a big difference in you getting a handle on them in your lawn. Each one has unique attributes that give you insight into how to stop them in their tracks. 

When you look at dallisgrass vs. crabgrass, you can easily mistake one for the other in your lawn. But while both of these weeds may look a lot like each other or even look a bit like your current lawn, there are actually some key differences when you look at them side by side. Here, we’ll point out some of their key distinctions so you can tell them apart.

The Height Difference Between Dallisgrass vs. Crabgrass

One way to recognize whether you’re looking at dallisgrass or crabgrass is to check their height in your lawn. 


This one is easier for you to tell the difference. Dallisgrass is a taller weed that stands more upright compared to crabgrass. Crabgrass typically sits lower to the ground and has broader leaves than dallisgrass.

The Weed Seeds Are Different, Too

These two weeds – crabgrass vs. dallisgrass – also can be identified by their seed head appearance. Studying them closely can reveal the differences. 

Dallisgrass seed heads are very large, and they have small black spots on them as they grow off the sides of the weed’s stems. 

Crabgrass with seedheads

Crabgrass seed heads, on the other hand, are smaller than dallisgrass seed heads and very fine in texture. They grow out of the top of the crabgrass stems vs. the sides.

The Growth Habits of Dallisgrass vs. Crabgrass

When you’re trying to tell whether you have dallisgrass or crabgrass in your Northern Virginia lawn, you may want to pay attention to how each weed grows because there are also differences there. 

Dallisgrass grows in a clump that slowly increases in diameter as its shallow, short, underground stems grow outward. Crabgrass, however, grows by seeds and has a prolific branching and tilling habit. A single crabgrass plant, in fact, can produce 150 to 700 tillers and 150,000 seeds, which is what makes it hard to control once it gets established in a lawn.  

Checking Out Color Differences Can Be An Easy Way to ID Your Weed

If you take a close look at the weeds in your lawn, you’ll notice a slight difference in color between dallisgrass and crabgrass as well.


Crabgrass is usually more of a bluish-green, while dallisgrass tends to be more of a pale green color.

Each Weed Also Grows Differently: One is Annual And One is Perennial

This category may be the biggest difference between dallisgrass vs. crabgrass. 

Dallisgrass is a perennial, which means it grows back each year from the same root system. It grows in solid, circulate clumps. 

Crabgrass, though, is an annual that germinates from seeds and dies in that same year, coming back from new seeds the next year. It spreads in a pointed fashion, widening as it grows similar to fireworks – just not the kind of fireworks that make you smile on the Fourth of July.

How to Control Dallisgrass vs. Crabgrass

Yes, when it comes to these two weeds that look similar but are actually very different, there are even two different ways to manage them in your Northern Virginia lawn. 

Let’s look at the distinctions between how you control dallisgrass vs. crabgrass so you can fight the right weed fight once you properly identify your weed problem.

How to Manage Dallisgrass

Pre-emergent weed control is not effective at stopping dallisgrass before it starts. 

lawn care expert sprays for weeds

This means using a selective herbicide is how to get a handle on this one. And you may need to use two applications to control this weed and prevent it from getting worse.

How to Manage Crabgrass

When it comes to crabgrass vs. dallisgrass, you must employ a different weed control strategy. 

Crabgrass is best controlled early in the season with a pre-emergent herbicide before the weed seeds have a chance to germinate and the weed begins growing and spreading. Using two applications during the prime treatment window in spring will help capture more of the seeds that are present and waiting to germinate. Usually the first treatment will take place by the end of March and the second treatment will take place with the next fertilization treatment. 

lawn care expert fertilizing grass

Then, if you’re still seeing some crabgrass break through after preventive treatments, or if the preventive treatments didn’t work as effectively on a thinner area of the lawn, the next step is to apply spot treatments of a post-emergent herbicide on small crabgrass plants that break through.

How to Prevent Both Crabgrass and Dallisgrass

Whether you’re fighting dallisgrass or crabgrass, there are ways to prevent them both. 

Both weeds like sun and warm temperatures. They also will take advantage of thin or stressed out lawns, so there are things you can do to keep your lawn thick, healthy, and green to enable it to withstand weed infestations.  

Follow these tips for a lawn that is more bulletproof against weeds:

  • Don’t mow too short. Mowing your lawn too short stresses it out. Mow to a 3.5- to 4-inch height to ensure your tall, thick grass blocks the sun’s light that could hit weed seeds and cause germination. 
  • Water properly. Water with a minimum of 1½ inches of water each week, keeping rainfall in mind. 
  • Thicken your lawn with annual aeration, overseeding, and topdressing each fall to increase lawn density, ensuring crabgrass doesn’t have as much of a fighting chance to emerge.

Whether You Have Dallisgrass or Crabgrass, It’s Time to Get Rid of It

Weeds never take time off. When the right conditions are present, they jump into your lawn and plan their takeover. 

To stay ahead of dallisgrass and crabgrass, you have to plan ahead. And that means working with a Northern Virginia lawn care service provider that knows how to battle these weeds and can also keep your lawn healthy with correct mowing, watering, and fertilization. They should also know the proper timing of weed applications to ensure control, keeping an eye on any breakthroughs. 

You want to be outside playing fetch with your dog and enjoying time with your children. You don’t want to be wasting time managing weeds.  

Let Turf’s Up help you get your time back. We can tell which weed is which and get down to business taking care of it in your lawn so you can worry more about fun and less about these problems in your grass. That’s what time outside is all about, after all.

Ready to learn why Turf’s Up could be your totally awesome choice for lawn care services in Northern Virginia? We’re stoked to learn more about you and help you have the best lawn on the block. Get started today with a free quote. Together, we can prepare a customized plan that is perfect for you and your lawn. 
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Image Source: Crabgrass Close Up