How To Get Rid Of Crabgrass For Good
Crabgrass is a nemesis of lawn lovers everywhere, including here in the Raleigh area. Its scientific name, Digitaria is a warm, seasonal plant that grows annually that many people consider a weed. The reason behind the name Crabgrass comes from its characteristic of sharing a common and shallow root system that appears to be spread out like a crab across the lawn.
What Is Crabgrass And Why Not Just Let It Grow
Crabgrass and other unwanted weeds steal valuable moisture and nutrients from the soil, taking them away from plants you value such as lawn grasses, flowers and vegetables. Crabgrass can also make a lawn look unkempt. As an annual grass sown from seed, when the plants die in the fall, they leave gaping holes throughout the lawn during the winter.
The first step in managing and repelling any intruder is to identify the enemy. Once you learn what crabgrass looks like, its important to learn several methods of controlling this weedy grass. Biological control of crabgrass is easier than youd think, but there are also several crabgrass control products available at your local nursery and garden center that kill unwanted crabgrass or prevent it from sprouting in the first place.
Maintaining A Lush Healthy Lawn
The key way to sabotage crabgrass is to maintain a thick, uniform lawn. The lawn should be healthy, with turf in good condition since crabgrass can easily overpower weak turf. Also, there should be no ruts or bald spots, because it is precisely here that crabgrass likes to take root.
Easier said than done, right? Its not enough to just wish for a healthy lawn to make it happen .
Lets discover a couple of tricks that will ensure you get and keep a healthy lawn.
Set your mower deck high! Most lawns are cut too low in fact, that is officially the number one mowing mistake. The golden rule is to cut only of the grass blade each time you mow. Giving the ideal mowing height for maintaining a thick turf being between 2 and 3.75 inches.
Quick tip: Water the lawn less frequently but deeply soak your entire lawn as a summer shower would. Frequent shallow watering can weaken your turf by preventing it from forming a deep root system.
Plus, constant surface wetness creates an ideal ground for the occurrence of turf disease.
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Crabgrass Longevity Or The Lack Of It
Crabgrass is an annual weed and it dies completely at the end of its life cycle. While that may sound like a good thing, because who wants the same weed to return year after year in the same spot, dead crabgrass will turn yellow-brown and spoil the consistent look of a perennial green lawn.
Besides that, crabgrass that was allowed enough to naturally die has already produced tens or a hundred thousand seeds that will germinate the moment they get some spring sunshine and warmth. And it is precisely these bald spots where the mother-plants have died that are the ideal for the sprouting of the new crabgrass generation.
Use A Spot Treat Liquid
If you havent been successful in preventing crabgrass from arriving in your garden, and the manual method hasnt worked, you could always try a spot treat liquid. This is an efficient way of removing clumps of crabgrass that is already established on your lawn.
Again, there are many useful products on the market, but make sure you find a lawn-safe herbicide that isnt going to kill your grasses as well as the crabgrass. One of the best products on the market comes from Ortho and can be purchased on Amazon:
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Why Is Crabgrass Bad
Crabgrass is not bad per se, its just not a desirable grass species to have on your lawn, even if its a mixed-species one.
Despite being a tough, resilient grass, and very nutritious forage for cattle, the way crabgrass grows makes it highly unsuitable for forming lawns. It is unable to form a uniform cover instead, it grows in bumpy clumps . Its aggressiveness is also a drawback for having it as a cover in gardens.
There are several reasons why people dont want it on or near their lawns.
How Do You Get Rid Of A Crabgrass Infestation
To get rid of a crabgrass infestation, follow these instructions:
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Using A Crabgrass Preventer
For those who don’t want to spend time on hands and knees pulling weeds, and who don’t mind working with chemicals, here are some tips for applying a preventer.
Crabgrass preventers are a type of pre-emergent chemical targeted to kill crabgrass, which you apply when it’s time for the crabgrass to sprout. Since crabgrass starts growing when the soil is about 54 degrees and a preventer lasts only 2-4 months, the time of year you apply it will depend on where you live. In Southern California, where it seldom gets really cold, you’ll likely apply the preventer in January, rather than in April or May, like in colder regions of the north.
One sure clue for timing is to watch for crabgrass sprouts near the edge of your driveway or sidewalk. Soil temperature is a little warmer there, so when you see the first seedlings emerging, that is a good time to apply your preventer. An even better way is to purchase a soil temperature gauge and apply it when the soil heat reaches 55 degrees three or four days in a row. Test several spots on the lawn to get an average.
Green Light Crabgrass Preventer is one of the rare pre-emergents that is not mixed with fertilizer, so you have more control over how much actually reaches the worst part of your lawn.
Dimension Crabgrass Preventer actually hits crabgrass hard after it’s sprouted, so if you missed the earlier deadline and your grass is well on its way to taking over, this would be the kind of post-preventer to use.
Prevent Crabgrass With Pre
Of all the lawn care products out there, pre-emergent chemicals are probably the most misunderstood and misused.
Most people rush to the stores the second the weather starts to get nice in early spring, and they load up on a step 1 product that most fertilizer companies push.
The step 1 for most of these companies contains a crabgrass pre-emergent and a fertilizer all in one. On the label you can find a very broad time frame of when you are supposed to apply.
Theres nothing wrong with applying a step 1 product to your lawn. But for it to be fully effective you have to have an understanding of soil temps.
If youre looking for a simple crabgrass pre-emergent strategy then apply the step 1 twice. Your first application should be when your soil temps are approaching 55 degrees, and your second application should be about 5-6 weeks later as soil temps approach 70. This is a fine strategy if you want to keep things simple.
If youre looking for a more effective pre-emergent for crabgrass as well as other broadleaf weeds then consider using the following products at the correct soil temperature:
1. Dimension: Dimension is a next level pre-emergent that is used by professionals. Dimension can be found in a couple of different products but my favorite and most accessible for homeowners is Lescos 19-0-7 Crabgrass Preventer.
Apply this product for your first two applications using the same soil temperature rules above .
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Some Options To Eliminate Crabgrass Naturally
For homeowners wanting a more natural approach to eliminate crabgrass, there are a couple of non-chemical options. These methods are more environmentally sustainable but may take longer to get rid of the weeds. You can pull weeds by hand or apply corn gluten meal as a pre-emergent.
The first option is to pull crabgrass plants by hand. To make pulling weeds easier and more successful:
- Pull crabgrass plants as soon as you see them. Smaller plants are easier to pull than larger ones.
- Try to remove all of the roots if possible when pulling crabgrass. Grab each plant by the base and pull slowly and steadily upwards.
- Weed just after it rains or water the lawn thoroughly.
- Use a weeding tool such as a hoe or a weed popper.
Manual removal is the most labor-intensive option and may not be feasible for homeowners with physical limitations.
Corn gluten meal can also be used as an alternative to chemical pre-emergents, applied at a standard rate of 20 pounds per 1,000 square feet of lawn. It is an organic approach that prevents roots from establishing after the seeds germinate.
Using corn gluten meal for crabgrass control isnt as straightforward as chemical options. Timing is critical and impacts the effectiveness considerably. Corn gluten meal may also take more than one application to see the full benefits, and it may not get rid of the crabgrass entirely.
How To Kill Crabgrass With Baking Soda
Baking soda is also effective for killing crabgrass. Just water the area with the hose on the crabgrass and then sprinkle the baking soda on the crabgrass. The crabgrass will begin to die. And remove the dead crabgrass from the lawn.
Then put the grass seeds on the bare spots. Use the baking soda sparingly because the heavy salt can damage your lawn.
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Use Baking Soda Vinegar Or Corn Gluten
If you are wondering how to kill crabgrass all-natural way, applying home-made killers such as baking soda, vinegar, and corn gluten is a great idea. Its the stuff all of us generally have in our homes, so it will also save you a trip to the store and save you some money.
Phytotoxin content of baking soda will do harm to any pant it comes in contact with. As with touring hot water, its best used in isolated areas and single patches of crabgrass.
Simply spray some water over crabgrass or any other plant you need to be destroyed for that matter and sprinkle baking soda powder over it. In the course of a few days, you will see the results and then uproot the dead plants, rake the surface and plant new grass.
Using vinegar is a great method of dealing with crabgrass since, while it has the same effect on plants as the
Roundup, it does no damage to the soil, and after you apply it ground is ready for reseeding. The best way to use it is by combining it with salt and liquid dish soap.
Vinegar and salt will dry the crabgrass out and soap will allow the plant to soak up the solution. Pour 1 gallon of vinegar, 1 cup of salt, and 1 tbsp of soap in a bowl or a bucket and mix it well. Spray the weed once a week, although youll generally notice the effect within a day or two.
One of the best organic preventers of crabgrass growth is corn gluten. It obstructs the development of weed roots.
Organic Crabgrass Control Methods
Beyond natural means, there are other organic means that can be used to help control crabgrass. If you need to completely replant your yard, taking black plastic and covering the ground, especially during the hot times of the year, will bake any weed seeds left in your soil and leave them unable to grow.
Another common organic method is using corn gluten meal as a pre-emergent, which will not only control the crabgrass by absorbing moisture away from the seed, but also provides fertilizer for your lawn and landscaping plants.
Like any pre-emergent, it needs to be put down at the right time, just as the chemical pre-emergent treatments above. Scattered at a rate of 10-30 pounds per 1,000 square feet, it provides a 9% nitrogen source that is released slowly into the soil. After application, be sure to water it in well and then allow it to dry to remove the moisture from the crabgrass seeds.
Because of the drying time that is required, corn gluten meal may not work well in areas that have excessive rainfall or have had a very wet spring.
Vinegar, or specifically the acetic acid in it, at more than 6% concentration. Most household vinegar is too low in concentration at 5%, but housecleaning vinegar is closer to 6% concentration. You can also increase the concentration by freeze distillation, basically putting the vinegar in a shallow plastic dish in the freezer, then removing ice crystals using a slotted spoon or skimmer.
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How To Get Rid Of Crabgrass Once Its Grown
As the name implies, pre-emergent herbicide wont work if the crabgrass has already started. Pre-emergent is only good for before the crabgrass grows as it prevents the seeds from germinating. Instead, if you already have crabgrass growing, you should use post-emergent herbicide products to control its growth.
Post-emergent herbicide works by killing the crabgrass that has already grown. The amount of herbicide you can safely apply to your lawn will depend on type of grass you have (speak with your lawn expert
General directions for post-emergent herbicide :
- Check the weather forecast before you apply. You want to apply it on a warm sunny day, and you dont want it to rain later that day or the next day. If it rains, it will wash the product away before the crabgrass can absorb the herbicide. The herbicides work best when the temperatures are higher . If its too cloudy or too cool, the product will be less effective.
- Make sure the soil is most before applying as this will also help absorption. If not, you should water the lawn and then wait until the next day to apply .
- For best results, apply in the morning after the dew has dried.
Note: If you notice the lawn browning suddenly, you probably applied too much herbicide. Also, please note that if crabgrass is well established, you may need to apply herbicide twice. If so, wait 4 to 7 days before reapplication. .
When Can You Plant Grass Seed After Applying Crabgrass Killer
Crabgrass killers do not differentiate between crabgrass seed and grass seed. It means you cant apply grass seed after the crabgrass killer application.
Some of the crabgrass control manufacturers recommend applying grass seed 4 months before the crabgrass killer. All of the crabgrass preventers contain different chemicals. So, some of them work better when spread close to the seedling time.
Thats why, read the instructions on the label of the herbicide.
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Solarize Large Patches Of Crabgrass
Something else you can do to help kill crabgrass seed is to wait until the sunniest and warmest period of the year, use your lawnmower to cut the plants as short as you can, apply a generous amount of water, and use a sheet of clear plastic to cover the ground.
This process is called solarization, and its a good way to kill a large section of grass or weeds.
You must ensure that the plastic isnt punctured in any way. Leave it on the ground for between a month and six weeks. During this time youll answer the same question repeatedly when all your neighbors ask what the heck youre doing, and the sheet and the ground beneath will heat the ground sufficiently to destroy all the seeds below it.
After this, you can reseed the area with grass seed, or lay sod.
Soil Temps Are Crucial
Crabgrass starts to germinate when your soil temperature hits 55 degrees. The best thing you can do is find out when your soil temperature usually hits 50 degrees and apply your crabgrass pre-emergent then. If you apply when soil temps are at 50, by the time it hits 55 the pre-emergent will already be in your soil.
Youre probably wondering how youre supposed to know when your soil temperature is 55 degrees. Luckily, there is a great site called Green Cast Online.
All you have to do is go to the site and enter your zip code. Look at the five day average and when it hits 50 degrees its time to throw down your first application.
About 5-6 weeks later you want to apply another round of pre-emergents as soil temps approach 70.
Once soil temps go above 80 degrees crabgrass germination comes to a halt. Adding a pre-emergent at this time wont be very effective. I should point out that at the end of summer as soil temps fall back down to 70 degrees there are fall germinating broadleaf weeds that can pop up. Thats why I recommend a third application of pre-emergents heading into fall.
For a better understanding of soil temperature and how it should be used in you lawn care program check out: The Importance of Soil Temperatures in Your Lawn
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