Crabgrass is like your lawn’s version of pests: Sometimes, you don’t notice an infestation until it’s too late. And, like pests, once they set in these weeds completely take over and reduce the overall quality of life for grass and other plants.
Worst of all, they manage to contaminate and kill neighboring plants with a form of self-propagated herbicides. A new study shows crabgrass attacks other plants using a strategic release of toxins, oppressing and inhibiting their growth.
This direct toxic effect, coupled with crabgrass’s unsightly growth and rapid production, make it a much-despised weed that crops up every summer. If you don’t take steps for mitigation, as early as February, even crabgrass preventer sprays might not work to stop their growth.
To get rid of crabgrass, you’ve got to stop their germination and use a crabgrass-specific elimination strategy. Here’s a quick look at everything you need to know:
What Is Crabgrass?
Crabgrass is an annual weed that acts like a perennial. Every year, its seeds sprout from the soil once the temperatures reach anywhere from 50F to 75F. Depending on your region, that’s around early to mid-March, continuing through the summer.
It’s easy to spot these prolific weeds as they produce over 150,000 seeds per plant and have a coarse, clumpy look with tall, yellow or green grass blades.
The leaves of crabgrass try to blend in with your lawn’s thin, long blades but don’t be fooled: Crabgrass leaves are thicker, stouter, and resemble a small corn plant. It’s not soft and comfortable to sit on, as your lawn might be. Instead, it’s dense and scratchy.
Crabgrass shoots are unsightly as well because the clumps look like dead patches on your lawn. The blades span anywhere from a quarter to a third of an inch thick and look almost trampled or flattened because side shoots develop and separate from the underside very quickly.
The worst thing about crabgrass is its rates of proliferation: Give it half a chance and this weed will crowd out your lawn, branching out rapidly, and sucking the resources from other plants in your garden.
But it’s not just your lawn that’s at risk. Because the primary source of crabgrass is the soil, it can pop up in your vegetable patches or flower beds, spreading its noxious natural herbicide and killing off these valuable plants.
4 Quick Steps to Remove Crabgrass
Whether or not you’ll be able to eliminate it all depends on the density of the plants and how quickly you notice the issue.If your lawn or soil bed has more weeds than grass, all you can do this season is hope to keep their growth at bay.
Use these four quick steps to remove crabgrass from your lawn if they’ve already begun to sprout:
1) Get Rid Of Seeds in the Soil
Your soil is the primary source of weed seeds. Since crabgrass is an annual weed, just pulling it out by the root is not going to cut it.
The plant produces seeds frequently and rapidly, getting into the soil and either sprouting right away or staying there until winter is over and the ground is warm enough to shoot up again.
This means that you’ll need to get rid of seeds in the soil, and the best time to do this is in the fall. Using a lawn rake, disturb the crabgrass at its roots and get them to rise upright, taller than your grass. This will eliminate the seedheads – even the hidden ones.
Next, mow the lawn and use a grass catcher to keep the clippings from returning to the soil.
2) Use a Crabgrass Killer Spray
Post-emergent herbicides are crabgrass killers you can spot-apply on areas that have crabgrass. They might help you kill the actual weeds, which makes it easier to pull them out. However, they’re not as effective as pre-emergent or preventative sprays — which we’ll talk about later.
3) Remove Crabgrass Already Present
Once the weeds have shriveled up and dried out, start to de-weed your lawn area. Using a lawn rake, you can work at the base of the root and pull it out. Use a small gardening spade to loosen the roots up as well. If your soil is compacted or dried out, it might be useful to wait until after a rainfall.
4) Replant Bare Patches of Soil
Once you’ve cleaned out your lawn or garden bed of these weeds, the remaining large, bare patches of soil need some care. Re-seed these areas with new grass seed or use small shrubs or plants. This also helps to avoid erosion.
If you do use a crabgrass killer herbicide, wait at least a month after application to re-seed again. Water these areas frequently and monitor your lawn for more outcroppings of crabgrass.
How to Prevent Further Crabgrass Growth
Crabgrass control is a timing game, but prevention is a much more effective and permanent solution to addressing its growth. Plan adequately in advance, and you’ll eliminate these nuisance plants.
Take out a calendar and plan out these four steps by season:
1) Aerate and Re-Seed Your Lawn in the Fall
If your soil is compacted or your lawn suffers through the summer season, take the time to aerate and re-seed your lawn.
Prepare your soil by removing large rocks and debris, working over the hardened spots with a tiller. Put down new grass seeds using a drop or rotary spreader, then mix in the seed and lawn food (fertilizer) to give your seedlings a fresh start.
2) Apply Pre-Emergent Herbicides
You can use pre-emergent herbicides as early as February. Hidden crabgrass seeds can be lodged two to three inches below the top of the soil, so this crabgrass preventer spray will need to get into the soil.
However, you’ll need to apply herbicides earlier than usual if your region experiences warmer winters. Plan to apply crabgrass preventer sprays when the soil’s temperature rises to 60F. Applications should be uniformly applied.
You should also plan to avoid thatching or aerating your lawn after herbicide application, as this could make the chemical bonds weaker. You can use the sprouting shrubs and trees on your property to time this application. Once these plants bud, you can apply the herbicide.
3) Choose the Right Mix of Turfgrass Seeds
Selecting the right turfgrass is a highly beneficial strategy for crowding out crabgrass seeds. Anything that competes with crabgrass is the best choice for your lawn.
Finding the right mix can be a process though. External factors like the amount of foot traffic, the climate in your region, growing seasons, and even sun versus shade all affect which grass you should choose. For example, Hybrid bermudagrass is very competitive, but it needs at least six hours of direct sunlight to thrive.
For northern states and cooler climates, cool-season species such as bentgrass, Kentucky bluegrass, tall fescues, and perennial ryegrass are most competitive against crabgrass. Choose these turfgrass seeds, and you’ll be able to crowd out any leftover crabgrass that hasn’t yet died.
4) Use a Careful Lawn Mowing Technique
How short or tall you keep your lawn’s height matters. The shorter you mow your grass, the easier it is for crabgrass seeds to move in and germinate. You can help crowd out crabgrass by carefully maintaining your lawn at the height of three inches.
Lawns measuring three inches are long enough to shade the soil from exposure. Water your lawn in the evenings but don’t overwater it. If you’ve done the fall aeration and re-seeding, it’s okay to keep grass clippings on your lawn, since these won’t include any crabgrass.
It’s surprising how quickly crabgrass can take over a lawn area.
Part of the issue is that it multiplies rapidly and aggressively. The other challenge that crabgrass presents as an annual weed that acts like a perennial. Just because you can’t see it during the winter doesn’t mean that it’s not embedded in your soil already.
But now, you know all the tips and tricks you need to control crabgrass in your yard. Follow our advice, and you can say goodbye to scratchy, unsightly lawns.