Your landscape comes to life when the weather warms up in the spring. However, warmer temperatures sometimes also bring lawn weeds along, including the infamous pesky crabgrass. Crabgrass is an annual opportunistic weed that grows everywhere there is bare soil, water, and sunlight in the late spring. Crabgrass keeps growing throughout the summer, and it doesn’t really start to look bad until the end of the season.
Photo by pollyalida
At the end of the season, it starts to distribute seeds, and then the harsh winter kills the crabgrass. However, the seeds survive and grow the following year once again. Crabgrass simply cannot be ignored owing to its aggressiveness and how quickly it can spread. So, you might be wondering how I can kill crabgrass and prevent it from returning?
Actively growing crabgrass on a lawn calls for the use of targeted, post-emergent herbicides such as Tenacity Herbicide containing Quinclorac or Image All-In-One Lawn Weed Killer. These post-emergent pesticides eliminate crabgrass while leaving your lawn grass untouched. However, herbicides containing quinclorac should not be used on lawns consisting of St. Augustine grass.
However, there are several other ways to control the spread and germination of crabgrass in your yard or garden. Keep reading to find out!
In order to successfully get rid of crabgrass, you must first understand its lifecycle and how it spreads and reproduces. Crabgrass seeds begin to sprout in the spring when soil temperatures reach 55 to 60 degrees Fahrenheit. This warm-season annual grassy weed sprouts, lives, and dies all in the same year.
Crabgrass issues, however, persist even after the growing season, thanks to its hardy seeds. Each crabgrass plant can produce up to 150,000 seeds over its lifetime. So, as soon as the first frost hits, the plants perish, but the seeds survive. These seeds remain viable for years and can germinate into new weeds even after years.
This is the reason why most crabgrass control and treatment options revolve around preventing the crabgrass seeds from germinating. Luckily, however, If crabgrass is a problem in your yard, you have more than one arrow in your quiver to kill it for good:
- If you see only a few crabgrass plants emerging on your lawn, simply pull them out of the ground. However, this will only work at the start of an infestation when the crabgrass plants have not set seeds.
- You can use a post-emergent crabgrass herbicide if the infestation is on the larger side. However, once again, post-emergent herbicides work best against young crabgrass plants, so you must be vigilant.
- However, the most effective method to kill crabgrass is using pre-emergent herbicides. They kill the crabgrass before even its seedlings can establish themselves, saving you from these pesky lawn weeds altogether.
What Is The Best Time To Kill Crabgrass?
Photo by NY State IPM
Timing is of critical importance when it comes to controlling crabgrass on a lawn. Ideal timing for control will vary depending on the treatment used. And a perfect treatment option will depend on the life stage at which crabgrass is being controlled.
Killing Crabgrass Before Emergence | Crabgrass Preventers
Pre-emergent herbicides prevent the crabgrass seeds from developing roots and establishing themselves in the ground. When using a crabgrass preventer or pre-emergence herbicide, follow the manufacturer guidelines. In general:
- Apply the pre-emergent herbicide when the ground temperature reaches or exceeds 60 degrees Fahrenheit for a few days in a row.
- Keep in mind that regional weather trends affect application times. For example, you might have to use the preventer early in areas with warm winters.
- To avoid destroying newly sown lawns, wait for at least three mowings before spraying your grass with a crabgrass preventer.
- Avoid aerating or dethatching the lawn after using the crabgrass preventer. This can weaken the herbicide’s chemical barrier, rendering it ineffective.
- If your lawn already has crabgrass or if you recently put in sod, avoid using a pre-emergent herbicide.
- After applying a pre-emergent herbicide to the grass, you should hold off on reseeding the lawn for at least three to four months.
- To stop any leftover crabgrass seeds from sprouting up in the next season, apply a pre-emergent herbicide in late winter or early spring of the following year.
Killing Crabgrass Post Emergence | Crabgrass Killers
If you have missed the opportunity to use a crabgrass preventer, there is no need to worry! You can always use a crabgrass preventer. Apply post-emergent herbicides as soon as you observe crabgrass plants growing in your yard or garden. It is because these herbicides are less effective on weeds that are older and established, so the earlier, the better.
Once again, ensure to follow all the manufacturer’s guidelines. In general:
- Check the local weather forecast before treating your lawn with a crabgrass killer. Calm, sunny days are best. Do not use herbicides when there is expected heavy rain; it will wash off the chemicals from the lawn.
- The type of grass you have will determine how much post-emergent herbicide it is safe for you to apply to your lawn.
- The product probably won’t work if the weather is too chilly or cloudy. Post-emergent herbicides function best when soil temperatures are around 55 and 80 °F.
- Water your lawn lightly after applying your grass with the crabgrass killer. If the weather is exceptionally dry, you might want to water it two days again after the application.
- Some crabgrass plants might escape the first round of post-emergent herbicide treatment. So, keep an eye out and be vigilant.
- You’ll need to spray the pesticide twice if the crabgrass plants are fairly well established. After the initial application, follow up with another treatment five to ten days later.
- If crabgrass covers the bulk of your lawn, it is preferable to avoid removing it during the summer. So, hold off and renovate the fall.
Organic Crabgrass Control
A healthy lawn is your best line of defense against crabgrass. Weeds and undesirable grasses simply cannot thrive in a healthy grass stand. Gardeners who employ organic methods must wait until the seedlings are large enough to be pulled by hand, roots and all; however, do it before the plant has flowered and produced seeds.
Crabgrass Control Schedule
Here is a rundown of the important dates that need to be marked on your lawn care calendar in order to keep crabgrass and its spread under control.
|Crabgrass seeds germinate when soil temperature hits 55 to 60 °F
|Use a pre-emergent herbicide
|Mid-Summer To Fall
|Crabgrass plants mature, flower, and set seeds
|Use a post-emergent crabgrass herbicide or uproot the weeds
|With the first frost, crabgrass plants perish, but seeds enter dormancy and remain viable
|Use a pre-emergent herbicide once again to prevent crabgrass germination
How To Get Rid Of Crabgrass Naturally?
You really don’t need to use any chemicals to control or kill crabgrass. Herbicides make it simple to eradicate crabgrass, but there are also a number of natural methods that can be used to do the same successfully. However, if you do not take adequate care of your grass or if the infestation is on a vast scale, these techniques may not be effective.
Pull Out Crabgrass
Photo by Matt Lavin
Even if you apply a herbicide to kill the crabgrass weed, you will still need to dig it out of the ground in order to eradicate it completely. The best time to hand-pull crabgrass is in the spring when plants are young and have not developed extensive roots, which will make pulling out crabgrass with hands extremely difficult.
Even though crabgrass doesn’t spread through its roots, removing the entire plant in the spring is still important before reseeding the area. Alternatively, you can use a weeder to pull out crabgrass from your lawn instead of using your hands.
Nevertheless, here is how to remove crabgrass manually:
- To help, use a hoe or a picking instrument. Aim to complete this before the seeds appear; once the seeds show up, crabgrass will spread quickly.
- To soften the soil, water the crabgrass-covered areas for around 30 minutes.
- Pull off crabgrass shoots in the spring before their roots grow deep. Bag these weeds to keep new seeds from spreading.
- In areas with little to no competing vegetation, crabgrass spreads quickly. Therefore, sow grass seed in any areas that are bare.
- Keep the grass well-watered, adequately fertilized, mulched, and mowed at a proper height to prevent future crabgrass infestations.
Digging and uprooting can also cause some harm to your lawn, so take care not to end up with a lawn that requires you to restore your sod, especially if there are extensive regions that have been invaded by crabgrass.
Use Baking Soda To Kill Crabgrass
Photo by David silver
Crabgrass is killed by baking soda because of its phytotoxic effects. However, depending upon the concentration and other factors of the soil in general, it may provide variable outcomes when used on different grasses.
Increased salinity as a result of sodium in the bicarbonate compound is extremely likely to be the primary weed control element of this home treatment. Also, keep in mind that any plant that comes into contact with enough baking soda will die.
Nevertheless, here is how to control crabgrass using baking soda:
- Wet the area of your lawn that is infested with crabgrass.
- Sprinkle the weed with baking soda, coating the site and the foliage.
- Allow the baking soda a few days to kill the crabgrass.
- Remove the dead crabgrass from the yard by using a shovel or a weeder.
- Next, reseed your lawn as leaving bare areas will encourage the growth of new weeds.
If you want to learn more about killing crabgrass with baking soda, read the article here.
Use Corn Gluten To Control Crabgrass
Photo by Phu Thinh Co
Corn gluten was first used as a supplementary ingredient in hog feed, but in recent years, it has emerged as a popular organic alternative to synthetic chemical herbicides.
In addition to having nutritional value, it is helpful as a pre-emergent herbicide for getting rid of crabgrass and other weeds in lawns.
Here is how to use corn gluten to control crabgrass on your lawn:
- Corn gluten should be applied between the end of March and the middle of April, at least three to five weeks before the seeds of the crabgrass begin to germinate.
- Spread the compound evenly on the grass at a rate of 20 pounds per 1,000 square feet, and then water the lawn lightly to work the corn gluten into the soil.
- After watering, make sure to give the soil some time to dry out so that any weed seedlings that emerge die as a result of the lack of moisture.
- Corn gluten can also be applied in mid-August to control late-season annual weeds.
Use Vinegar To Kill Crabgrass
Photo by Smallbrainfield
If you don’t like how crabgrass looks on your lawn or garden, you could try using vinegar to fend it off. The more acetic acid there is in the vinegar, the more effective it will be at killing crabgrass. Unfortunately, vinegar for homes only contains around five percent acetic acid. So, we suggest you get horticultural vinegar with about 10 to 20 percent acetic acid.
Crabgrass is eradicated by applying vinegar to the soil as it causes the grass blades to wither and makes the soil too acidic for the grass to thrive in. Additionally, vinegar can harm the crabgrass’s roots and prevent it from growing further. If you want your vinegar solution to have an even better effect, add some dishwashing soap to it.
This helps to break down the waxy layer that is on the crabgrass leaves, which then allows the vinegar to more easily penetrate the plant’s cell structure and kill crabgrass more quickly. Here is how you can kill crabgrass with vinegar:
- Add salt, dish soap, and vinegar to a plastic mixing cup and shake it well.
- Apply crabgrass with a reasonable amount of this vinegar mixture.
- Repeat the entire process 2 to 3 times unless the crabgrass perishes.
Be very careful not to use the vinegar on your grass, as it will destroy any plant with which it comes into touch.
Burn The Crabgrass
Photo by pxhere
You can eliminate crabgrass from your yard by burning it with a blow torch, a heat gun, or a weed burner. Subjecting crabgrass to high temperatures results in the death of the cells found in the stems and leaves of the plant. As a result, it will no longer be able to produce food, and the weed will perish almost immediately.
Burning is an effective way to get rid of grassy weeds without using chemical pesticides. In addition, burning returns the organic matter to the soil, which increases soil fertility. However, do not try flame weeding in a dry yard.
You run the possibility of grass fires, which can be hazardous due to the rapid rate at which they spread. Even in an area with a lush lawn, you need to take precautions to protect yourself and your property in case a fire breaks out.
Chemical Crabgrass Control Options
Here are three ways you can kill crabgrass by using chemicals:
Control Crabgrass Using Roundup
Photo by Mike Mozart
Roundup is a non-selective chemical herbicide that contains glyphosate as its active ingredient. Here is how you can get rid of crabgrass using roundup:
- Fill one gallon of water into a clean, chemical-resistant bucket. Add 2.25 ounces of Roundup herbicide to the water and carefully mix.
- Keep mowing around the crabgrass for about two weeks to give it time to grow taller than your lawn before treating it with roundup.
- Move the diluted Roundup herbicide into a spray bottle and apply the herbicide to the crabgrass foliage to the point of saturation.
- As an alternative, you may soak a sponge in the roundup and cover the top of the crabgrass with it.
- Wait ten days. Adjust the height of the lawn mower to its lowest setting, and then mow over the dead crabgrass.
- To ensure that the roundup completely kills the weed, you might need to treat the crabgrass two to three times over the period of two weeks.
Control Crabgrass Using Pre-Emergent Herbicides
A pre-emergent eliminates the weeds before they sprout from the ground and is sometimes referred to as a crabgrass preventer. It’s a frequent misconception that pre-emergent herbicides prevent seeds from germinating. However, the truth is that the pre-emergent herbicide forms a barrier layer on the lawn’s surface when applied, causing young seedlings to perish when they come into touch with the barrier.
Pre-emergence herbicides must therefore be used before the crabgrass seeds germinate. However, if the crabgrass preventer is used too soon, crabgrass seeds that grow later in the season won’t be controlled. And, if the preventer is used too late, crabgrass seeds would have already germinated, rendering the treatment ineffective.
Here is a list of my favorite crabgrass preventers:
Syngenta Tenacity Turf Herbicide
Photo by amazon
According to my experience and tests, this combination of crabgrass killer and preventer is the best and most effective. It acts as both a pre-emergent and a post-emergent treatment in one convenient package. It is very good at killing crabgrass but will not kill lawn grass.
Scotts Halts Crabgrass & Grassy Weed Preventer
Photo by amazon
The Scotts Halts Crabgrass and Grassy Weed Preventer is entirely resistant to the weather and will keep your lawn free of weeds throughout the growing season. When it comes to crabgrass prevention, I like to use Scotts, and when it comes to post-emergent weed control, Tenacity is my best bet because it is effective and does not harm my lawn.
Control Crabgrass Using Post-Emergent Herbicides
Post-emergent herbicides eliminate existing weeds. When used on young, delicate weeds like crabgrass, they are especially successful at eliminating difficult-to-kill weeds. However, multiple treatments might be necessary to eradicate mature weeds, which can be detrimental to the nearby plants and grass.
The best crabgrass killer for your lawn may depend on a number of variables. For example, do you prefer a product that exclusively targets crabgrass or one that kills other weeds as well? Also, will the herbicide be used during the weed’s active growing season or in its dormancy?
So make sure to do your research before choosing a crabgrass killer for your lawn. Nonetheless, here are my favorite crabgrass killers:
Preen Lawn Crabgrass Control
Preen Lawn Crabgrass Control prevents broadleaf weeds including crabgrass for up to four months when applied before seed germination. However, avoid using this product on a lawn that has recently been seeded because it will stop the grass seeds from sprouting. Apply in the spring or the fall for the better result.
Spectracide Weed Stop for Lawns + crabgrass
The Spectracide 511072 Weed Stop for Lawns + Crabgrass is designed to destroy more than 470 weed species to the root in just 5 hours, including crabgrass. You could notice that certain grass varieties turn a different color following the application, but this change will become less noticeable once the crabgrass has died.
Fight Crabgrass With A Healthy Lawn
Photo by Jeremy Page
Use these tips and tricks to establish a dense turf. A lush lawn provides a thick canopy of grass blades where weed seeds won’t germinate or grow.
- Water your lawn once a week to promote the grass to develop a deeper root system, making the entire lawn more resilient.
- Reseed as necessary. Weed-damaged or thin regions should be sown in the fall when days are warm, nights are chilly, and mornings have dew.
- Maintain a two to three-inch height trim on your lawn. Cutting it shorter than two inches can weaken the grass and allow weeds to take root.
- Ensure that the soil in your yard is not compacted. Weeds flourish in soils that have been compacted, and it denies the grassroots the air and water circulation that is necessary for healthy grass growth.
Frequently Asked Questions (FAQs)
Should you pull out crabgrass?
The crabgrass that has reached maturity has seed heads with forks containing thousands of tiny seeds. Pulling these plants will disperse the seeds across the lawn. Therefore, such plants should be left alone. However, plants with closed seed heads can safely be pulled out. It is also helpful to moisten the soil before pulling the weeds from the ground.
Why is crabgrass taking over my lawn?
Crabgrass is an annual weed that thrives on soil that has been compacted and thrives best when the surrounding grass is weak and thinning. During the warm months of summer, crabgrass grows at an accelerated rate. Each crabgrass plant produces thousands of seeds during summer, accelerating its spread.
Does crabgrass come back every year?
Crabgrass is a warm-season annual that grows, matures, and dies all in the same year. Crabgrass issues, however, persist even after the growing season. Each crabgrass plant can produce hundreds of thousands of seeds over its lifetime. Those seeds are left behind, waiting to bloom the following spring and restart the cycle.
Will dethatching remove crabgrass?
A dethatcher can pull away some of the crabgrass but cannot remove all of it. The crabgrass will, in any case, disappear throughout the winter. The heart of the issue is the seed that these plants drop, which will germinate the following year.
What does crabgrass look like on a lawn?
Crabgrass is coarse and light-green. Its slender stems resemble a crab’s legs. It is frequently confused for fescue grass. However, color and size are helpful distinguishing characteristics. Tall fescue grass has a darker green color, is dense, and develops quickly.
Sources For Further Reading
Tips for controlling crabgrass in your lawn – University of Minnesota Extension Service
Control of Crabgrass in Home Lawns – University of Illinois Turfgrass Program
Crabgrass control during a hot summer – Michigan State University Extension Service
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