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Winning the War Against Crabgrass!

Do you look at your lawn hoping to see a velvety carpet of perfect green turf, only to find tufts and clumps of raggedy crabgrass? Don’t be troubled! There are steps to take to rid your lawn of this “opportunistic weed” as well as prevent it from returning or appearing in the first place.

Here is a brief overview of crabgrass – what it is, how it grows, what you can do to rid yourself of it and how to prevent it.

Why do i have crabgrass

What is crabgrass?

Crabgrass is a very invasive weed that can sprout nearly anywhere there is water and sunlight. It is an annual plant that re-seeds prolifically which is why it is important to try to control it as soon as you see it. A small patch one year can become a large area in a few seasons if left unattended.

crabgrass in turf

Why is it called crabgrass?

Crabgrass has creeping stems that root freely and shoot out from the side, giving it a crab-like movement growth pattern.

How does crabgrass grow?

Crabgrass seeds germinate when soil temperatures reach between 55 and 60 degrees – in our area, somewhere after the forsythia bloom but before lilacs start to flower.

cure crabgrass

While crabgrass, like most weeds, may seem unsightly, it actually provides a necessary function in nature, helping to loosen soil so it can more readily absorb water and nutrients and restore it to the healthy microenvironment it should be. So you can either look at crabgrass as a nuisance or as a red flag to address the overall health of your lawn and its soil. Compacted areas and bald spots are indicators that your lawn needs some TLC.

Does crabgrass only appear in lawns?

No. Crabgrass also has the ability to grow in sidewalk cracks, along walk and driveway edges, in between patio stones, along garden edgeways – crabgrass is nothing if not opportunistic, and if it sees even the smallest of open spaces, it will vie to occupy it.


What is the lifecycle of crabgrass?

This annual grows all season – spring through fall. Early in the season you’ll see it in clump formations. Towards the end of summer and beginning of fall, tall seed heads form, which is how crabgrass re-seeds itself.
Crabgrass seeds are very hardy and can remain viable in the soil for years. Mowing crabgrass will not eradicate it. Crabgrass is killed off during the cold St. Louis winters, but the seeds remain for next season.

Why do I have crabgrass in my lawn?

This could be from two very common reasons.

  • Bare Spots: Crabgrass is an opportunistic weed that will pop up anywhere there is bare soil that receives sunlight. Common areas includes near the driveway where the desirable turf grass has been reduced from driving over it or the heat of the summer asphalt reflecting off the blacktop.
  • Mowing Too Short: Having a thick, lush turf will prevent the crabgrass and seeds from getting the sunlight they need to develop.

How to control crabgrass – elimination & prevention

The number one way to prevent crab grass is to cultivate a healthy lawn. A healthy lawn has rich, aerated soil, that allows water and nutrients to flow easily, enabling grass to grow in thick and lush with deep, well-anchored roots. This leaves no room for shallow-rooted, looking-for-any-open-space-to-grow crabgrass.

Proper timing for coordinating lawn replenishment with crabgrass control can be tricky. A general rule of thumb is to eradicate crabgrass in the spring, and re-seed your lawn in the fall. Applying a pre-emergent herbicide to prevent crabgrass also prevents turf grass seed from germinating. That is why trying to grow new turf grass while eliminating crabgrass can be an ineffective effort. Read more about spring vs fall seeding here.

Existing crabgrass can be eliminated by simple hand pulling (after a good rain weeds can be more easily uprooted) and/or by the application of a post-emergent (after seed germination) herbicide.

Pre-Emergent Control

Crabgrass prevention can include the application of a pre-emergent (before seeds germinate) herbicide. The pre-emergent product becomes active in the top layer of soil where crabgrass seeds sprout. The seeds actually do sprout, but can’t grow, thereby effectively killing the crabgrass. Crabgrass seeds can remain viable for years.

fertilization and weed control

Once applied, the pre-emergent becomes activated after a good rain or watering, and acts like a type of barrier. This is important to understand since anything that might break that barrier – weed pulling, lawn aeration, your dog digging – will compromise the effectiveness of the pre-emergent. Opportunistic crabgrass will find the breaks in these barriers and attempt to establish itself in these spaces.

There are other tricky aspects to controlling crabgrass – proper timing for applying pre-emergent herbicide is important. If the ground is too cool, it won’t activate. Wait too long for it to warm, and the crabgrass seeds will have begun to sprout.

Dowco has the expertise, equipment and products to help you restore your lawn and eliminate crabgrass. We’ll work with you to get your lawn to the velvety green carpet of your dreams.


Interested in working with us?

Send us a quick note with your project details and we’ll work up a free quote for you.

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Topics: Seasonal Yard Maintenance Turf Care Dowco Specific Fall Turf Renovation

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