How to Get Rid of Crabgrass

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Let’s face it, weeds are annoying. And seeing the beautiful lawn you have worked for invaded by unattractive weeds can be discouraging. Fortunately, there are ways of getting rid of the weeds growing on your lawn.

You may be asking yourself: what is crabgrass and how bad is it for my lawn? Well, let’s get right into it. Like other types of weeds, crabgrass can take the beauty out of your lawn and spread rampantly if left unattended to. What’s different about crabgrass when compared to other weeds is that crabgrass plants germinate, live and die all in a single year. So the actual plant doesn’t keep returning year after year like other lawn weeds do. However, the damage crabgrass plants do in that one year can have a lasting impact on your lawn. In order to prevent this from happening to your lawn, it’s a good idea to find out all you can about the crabgrass cycle and how to prevent it from wreaking havoc on your lawn.

Understanding the Crabgrass Cycle

Crab grass completes its entire life cycle in a single year. It sprouts up during the warm season and thrives until the temperatures become too hot or too cold. Unfortunately, crabgrass seeds do not die when the plant does. During its lifespan, a single crab grass plant can produce up to 150,000 seeds. This means that after the crabgrass plant dies, it leaves all these seeds that are just waiting for the right time to germinate in the next growing season. The cycle continues to repeat itself year after year.

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Gaining an understanding of the numbers of seeds that the plant reproduces gives you insight on just how damaging crabgrass is to a lawn and how difficult it is to get rid of it once it germinates and begins to produce seeds. That’s why crabgrass control is so important. Staying ahead of this cycle by preventing crabgrass plants from growing in the first place is critical to the health of your lawn.

The problem is that once crabgrass seeds germinate and grow there is little you can do to stop them. Mowing your lawn will not prevent the seeds from being deposited in the soil because crab grass plants can set their seeds as low as half an inch off the ground. And cutting your lawn down to this height or lower is not recommended for most lawns. So prevention is really your only option for killing crabgrass. Getting rid of crabgrass plants before they produce seeds should be the goal.

Preventing Crabgrass Plants

We often hear the phrase “prevention is better than cure”. This couldn’t be truer for crabgrass. In general, treating weeds before they become a problem is in the best interest of your lawn. Crabgrass, in particular, can be tough to deal with. This is because it is deceiving in nature. One might see the dead crabgrass plants when winter ends and assume the problem is gone for good. But as we have discussed already, there is more to the story.

Preventing of Crabgrass Plants by Sodding Canada

Getting to the root of your crabgrass problem, literally, requires you to disrupt the lifecycle of the crabgrass plant and prevent crabgrass plants from producing seeds and planting them in your lawn. If you prevent the plants, you prevent the seeds. There are some crabgrass preventer products on the market called pre-emergent herbicides. These stop the crabgrass plant right in its tracks – before new seeds can penetrate the soil.

Pre-emergent herbicides are effective because they not only prevent seeds from germinating, they also stunt the development of roots in new seeds. Without these critical elements, seeds have no chance of becoming plants.


Crabgrass prevention needs to be done at the right time in order for it to be effective. For successful prevention of the seedlings emerging, crabgrass preventers need to be applied to the plant before seeds germinate. This typically happens anytime from early spring until late summer. This is when soil temperatures are perfect for crabgrass seed germination. Once the soil reaches the ideal temperature of 55° and remains at this temperature or above for at least four or five days consecutively, germination begins and continues until the soil temperature goes above 90°F.

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We recommend that you purchase a soil thermometer at a garden centre near you. There are a number of brands that sell these at an affordable cost. Using a soil thermometer makes a huge difference because you can monitor the temperature of your soil easily and know exactly when to apply your crabgrass killer.

We recommend that you purchase a soil thermometer at a garden centre near you. There are a number of brands that sell these at an affordable cost. Using a soil thermometer makes a huge difference because you can monitor the temperature of your soil easily and know exactly when to apply your crabgrass killer.

In addition to soil temperatures, there are also some clues that you can get from nature. Other plants like yellow-blooming forsythia shrubs bloom fully at the same temperature that is a deal for crabgrass germination. So this can serve as a signal to you.

Where possible, get a crabgrass preventer that will be effective for the entire window – about five months – when crabgrass seeds can grow.

Some other things you can do to prevent crabgrass from growing are:

  1. Mow your grass at the proper height – Each grass type has a specific mowing height that is recommended. So make sure that you adjust your mower so it’s at the correct setting for your type of grass. Longer grass blades provide shade over the soil and deprive crabgrass seeds of much needed sunlight, and ultimately prevent the germination of these seeds.
  2. Deep water your lawn – One of the best ways to encourage a healthy lawn is to promote the development of deeper roots. You can achieve this by deep watering your lawn, which means that the grass roots need to grow deeper into the soil in order to access water. Since weeds typically have more shallow roots, when you water your lawn more frequently than you should, there is more water supply for the weeds. However, when you water your lawn less frequently and more deeply, weed roots won’t be able to reach the water.

Killing Existing Crabgrass Plants

Pre-emergent herbicides are not effective after crabgrass seeds germinate and the plant begins to sprout out of the ground. By this time, it’s too late and the only option is to use post-emergent herbicides. These will target the actual plant and not the seeds and kill any existing plants before they have the opportunity to produce more seeds.

There are two categories of herbicides on the market: selective and non-selective. Selective herbicides work towards killing specific weeds or plants categories, for example, grassy plants or broadleaf plants. As the name suggests, non-selective herbicides target all types of plants including lawn grasses and other plants that are growing that you may actually want to grow.

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Since crabgrass is a grass, general herbicides and fertilizers which are collectively called weed & feed fertilizers are not effective in killing crabgrass. This is why it’s important to read the labels of any herbicide you plan to use to make sure that it will actually achieve the desired result and kill off any crabgrass that may exist on your lawn.

There are some products on the market that will continue to work and prevent crabgrass for as long as 5 months. These kinds of products target the seeds of crabgrass but also can affect the germination of your lawn grass seeds. That’s why it’s important to follow instructions properly to ensure that you are using herbicides properly and not causing any damage to your lawn. As the rule of thumb, wait for at least 60 days and at least two mowings before you overseed your lawn in areas where you have used crabgrass preventers.


What causes crabgrass?

Crabgrass is a weed that thrives in warm summer temperatures. It may start off with just one crabgrass plant growing, however, each plant can produce tens of thousands of seeds. Even though the plants will remain dormant throughout the winter and then die, the seeds they leave behind will begin to grow when temperatures become ideal again.

Will vinegar kill crabgrass?

One of the natural ways to kill crabgrass is to use vinegar that has an acidity of 5 percent or more. Vinegar is an excellent option because it can kill the crabgrass without damaging the soil. Using vinegar can keep crabgrass at bay for up to 13 weeks. The higher the acidity of the vinegar is, the more effective it will be in killing crabgrass plants.

When should you kill crabgrass?

The most effective way to kill crabgrass is to target the seeds and prevent them from germinating. Since mid-spring to mid-summer typically has ideal temperatures for crabgrass seed germination and growth, taking measures to prevent the seeds from germinating during spring and summer is key.

Does mowing crabgrass spread it?

Mowing your lawn can spread weed seeds including crabgrass seeds. In fact, mowing your lawn too low can also promote weed growth and make it even harder for you to kill crabgrass. Many people don’t realize that their lawn mower blades can spread weeds across a beautiful lawn. So what this means is that you may actually find yourself having more of a weed problem the more you mow. That’s why it’s so important to prevent crabgrass and other weeds from growing in your lawn.

Does baking soda kill crabgrass?

Yes, baking soda is quite an effective way to kill weeds. It is phytotoxic, meaning that it has properties that are toxic to plants. Baking soda has proven to be effective in killing crabgrass, however, it may not work as efficiently for other types of grasses. How effective it is depends on the concentration of baking soda in the solution and the condition of the soil.

Why is crabgrass so bad?

Crabgrass is a threat to a healthy lawn because of each plant’s ability to produce up to over 150,000 seeds. Even though the crabgrass plant itself only lives for a year, it produces numerous seeds that can survive the winter weather and germinate when temperatures warm up and are most ideal. Each of these seeds can produce even more the next season and so it is a cycle that is difficult to get a handle on once crabgrass begins to germinate.

Do I need to pull dead crabgrass?

You may feel the need to pull out dead crabgrass plants because they are unattractive on the lawn. However, doing so is not going to prevent the germination of the seeds or take care of the problem in any capacity. Pulling up the dead plant is ineffective because by this time, the new seeds have already germinated.

What is the best time to apply crabgrass preventer?

The best time to treat your lawn with a crabgrass preventer is in the spring when the temperature of the soil reaches between 55 and 60°F and stays at this temperature for several days in a row.

Do crab grass roots die in winter?

Yes, the entire plant will die off during the winter. But remember that the seeds will survive the winter and remain dormant until the weather warms up during the spring. So while the plant does die each year, it leaves behind many seeds that will germinate and turn into even more crabgrass plants.

When all is said and done, crabgrass is one of the more difficult weeds to get rid of but, don’t be discouraged if you have a crabgrass problem. While it may take some time, there are ways that you can prevent more crabgrass plants from growing.

Just remember the important things when it comes to crabgrass control. Timing is everything. Treat your lawn with crabgrass preventers as soon as temperatures become ideal in the spring for the germination and growth of crabgrass seeds. By following the advice in this article, you can be well on your way to a beautiful and healthy lawn.

Should you have any questions about how you can get rid of crabgrass, feel free to reach out to us and will be happy to provide more information.