Believe it or not – one of the best times to stop crabgrass is when it’s most active – right in the middle of late summer and early fall!
Many homeowners think they have to wait until spring to do something about crabgrass. While spring pre-emergent treatments certainly help prevent new plants from sprouting, they do very little to solve the problem that is already growing in your yard.
The good news? As summer begins to wind down, crabgrass becomes much easier to spot, remove, and eliminate. Even better, once you clear it out, you can immediately reseed those bare areas so healthy grass takes over instead of allowing another generation of weeds to move in.
Why Late Summer Is The Perfect Time To Put A Stop To Crabgrass
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The key to putting a stop to crabgrass is taking action before it has a chance to produce and scatter thousands of seeds. A single mature crabgrass plant can produce tens of thousands of seeds that remain in the soil for years, creating new problems every spring if they aren’t stopped now.
By late summer, crabgrass is usually fully mature and easy to identify. Unlike many lawn grasses that grow upright, crabgrass spreads outward in a low-growing circle with thick stems radiating from a central crown.
Its lighter green color also makes it stand out against healthy turf. This makes finding every plant much easier than earlier in the season when it often blends into the lawn.
Because the plants are larger, they are also easier to pull from the ground with most of the root system intact. This is especially true after a rain or after watering the lawn the day before. More importantly, removing crabgrass now prevents it from dropping seeds that will germinate next spring.
Why You Can’t Let Crabgrass Go To Seed
One of the biggest mistakes homeowners make is simply ignoring crabgrass until frost kills it.
While the first hard frost will eventually kill every crabgrass plant, the damage has already been done if it has produced seed heads. Those seeds fall into the soil and patiently wait through winter before sprouting the following spring.
That means every crabgrass plant you leave standing this fall can create hundreds or even thousands of new plants next year. Stopping that cycle is one of the biggest keys to finally winning the battle against crabgrass.
Even if you don’t have time to eliminate every single plant, removing the largest ones before they mature and release seeds can dramatically reduce next year’s infestation.
Digging Crabgrass Out By Hand
If your lawn only has scattered patches of crabgrass, hand removal is often the fastest and most effective solution.
The secret is removing the entire root system. Crabgrass grows from a central crown just below the soil surface. If that crown remains in the ground, the plant can continue growing until frost.
A simple hand weeder, dandelion puller, or narrow garden trowel works perfectly. Slide the tool beneath the center of the plant and gently lift while pulling upward. When the soil is moist, the entire plant usually comes out quite easily.
Try to disturb as little surrounding grass as possible. Once removed, gently level the area with a bit of fresh topsoil if needed before reseeding. If the crabgrass already has seed heads, carefully place the plants into a bucket or lawn bag instead of leaving them on the lawn. This helps keep mature seeds from falling back onto the soil.
Spraying For Large Infestations To Stop Crabgrass
If crabgrass has spread throughout large sections of your lawn, digging every plant by hand may not always be practical.
In those cases, using a post-emergent crabgrass spray is really the only effective way to eliminate existing plants before they go to seed. There are many post emergent herbicide choices that can kill crabgrass and leave your grass still growing – but if you want to avoid using chemicals, there are natural herbicides that work as well – you just have to use them in a small sprayer to spot spray the crabgrass.
One natural solution for this that is very effective it Earth’s Ally Weed and Grass Killer, made with sea salt, vinegar and soap. This solution is safe for use around children and pets. Affiliate Link: Earth’s Ally Grass & Weed Killer Spray, 1 Gallon
Spot spraying individual patches instead of treating the entire lawn is often the best approach. It uses less product while protecting healthy grass around the affected areas. This should be applied only to the crabgrass as it will kill what it touches. Another alternative for this is straight horticultural vinegar with a strength of at least 30% acidity. Affiliate Link: HARRIS 30% Vinegar Concentrated Extra Strength
Most products work best when applied to actively growing crabgrass during dry weather when no rain is expected for at least 24 hours.
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Never Leave Bare Spots Behind
One of the biggest mistakes homeowners make after removing crabgrass is leaving bare soil exposed. Bare soil is exactly what crabgrass loves.
Crabgrass seeds need sunlight and open space to germinate. If the area remains bare, chances are another crop of crabgrass or other weeds will quickly move in. Instead, reseed every bare area as soon as possible after removing the weeds.
Late summer and early fall provide nearly perfect conditions for growing cool-season grasses. The soil is still warm from summer, cooler air temperatures reduce stress on new seedlings, and fall rains often provide consistent moisture. These conditions help new grass establish quickly before winter arrives.
Choose a quality grass seed blend that matches your existing lawn. Lightly rake the area and spread the seed evenly. Then, gently cover it with a thin layer of compost or topsoil to keep the soil consistently moist. This will help speed germination.
As the new grass thickens, it naturally crowds out future crabgrass by shading the soil and competing for water and nutrients.
A Thick Lawn Is The Best Defense To Stop Crabgrass
Healthy, dense grass remains the best long-term solution for preventing crabgrass. Crabgrass almost always invades thin, weak lawns where sunlight easily reaches the soil surface. Thick turf blocks much of that sunlight and leaves very little room for weed seeds to sprout.
In addition to reseeding bare spots, continue mowing your lawn at the proper height for your grass variety. Taller grass provides more shade to the soil while developing deeper roots that naturally compete with weeds.
Regular watering during dry periods and annual fertilizing also help strengthen your lawn, making it much harder for crabgrass to gain a foothold.
Don’t Forget About Spring Prevention To Stop Crabgrass
Although late summer and fall are the perfect time to eliminate existing crabgrass, next spring is when you can prevent new plants from emerging.
Applying a quality pre-emergent herbicide in early spring creates a barrier that stops many crabgrass seeds from germinating. See our article: The One Secret To Stop Crabgrass In The Spring.
However, remember that pre-emergent products should only be used in lawn areas that won’t be seeded. They also prevent desirable grass seed from sprouting. If you reseeded areas this fall, wait until the new grass has fully matured before using pre-emergent products in those locations.
Combining fall removal with spring prevention creates one of the most effective long-term strategies for keeping lawns nearly crabgrass-free.
Late summer and early fall truly are the best time to put a stop to crabgrass – and finally start winning the battle for a beautiful lawn. Happy Gardening! – Jim & Mary.
The Farm @ Old World Garden
Jim and Mary Competti have been writing gardening, DIY and recipe articles and books for over 16 years from their 46 acre Ohio farm. The two are frequent speakers on all things gardening and love to travel in their spare time.
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