How to Get Rid of Crabgrass Without Chemicals
Homeowners who take pride in keeping a beautiful garden are always concerned about weeds on their lawns. Weeds like crabgrass are very aggressive, and once they make their way into a lawn, they soon take over the entire area and even flower beds, making the garden look overgrown and unmaintained.
There are at least 30 different species of crabgrass. However, the most common species in North America are Hairy crabgrass (Digitaria sanguinalis) and smooth crabgrass (Digitaria ischaemum). Both species resemble each other, and control methods are the same.
Published: October 21, 2022.
Each plant of crabgrass can produce hundreds of thousands of seeds and can grow from a garden’s most productive spot to the barest, unhealthiest corners. Plus, it keeps coming year after year. Since this is the era of organic farming, gardeners today want an organic solution to eradicate stubborn weeds like crabgrass.
As such, chemical treatments can handle crabgrass easily. However, more natural crabgrass killers are anytime better to keep one’s garden, family as well as environment protected from chemicals that have long-term harmful effects.
It’s wrongly assumed that crabgrass can be eradicated only with chemical killers. However, that’s not the case. There are many natural weed killers that can do the job equally effectively and more safely. One just has to remember any concerns, such as kids and pets, while choosing the best natural crabgrass-killing method for their lawn.
In several parts, late summer means crabgrass. Some summers are especially good for crabgrass, meaning bad for lawn grasses.
To control crabgrass, gardeners have to understand what’s happening on their lawn during this time of the year and also how crabgrass grows.
Understanding Summer Lawns and Crabgrass
Gardeners should take the following things into consideration:
- Summer creates a lot of stress for lawns.
- Heat and drought are the conditions that considerably damage the lawn.
- Additionally, gardeners are not as forgiving about the lawn’s looks in the summer as they are in the winter.
- They want their lawns to look lush and green in the summer for outdoor activities.
- They try to oppose nature by continuously fertilizing, watering, and coaxing new growth out of their lawns, no matter what the weather is like.
- Cool season grasses, like bluegrass, rye, and fescue, grow best when temperatures are in the 60s range.
- Once temperatures reach in the 80s range, lawns will start to struggle a bit.
- Growth decelerates, color fades, and lawns will start showing signs of wear and tear since they are less able to recover from stress and traffic.
- Some cool season lawns will even go dormant in the summer, looking brown and brittle until early fall when they revive back.
Gardeners should also understand some facts about crabgrass:
- Crabgrass is an annual warm-season grass.
- It keeps coming every year from seed.
- It loves hot, dry weather and thrives in temperatures of 80-degree and above.
- Furthermore, crabgrass takes over just as lawn grasses slow down.
- It will take benefit from bare patches on the lawn.
- It loves hot spots by paved walkways and driveways.
Timing is Important
Gardeners should remember that it’s important when they start their efforts to kill crabgrass.
There’s a big difference between controlling annual grass weeds and perennial grass weeds. Annual and bi-annual grass weeds have a dormancy period, while crabgrass thrives all year round, which is why it’s sometimes considered as a perennial weed.
Crabgrass thrives in the spring and summer, i.e., from March to October. Here there are two timing tips that will help gardeners eradicate crabgrass from their lawns.
1. For spring, just before this weed’s germination, gardeners should apply a pre-emergent herbicide. This will stop seeds from germinating on their lawn.
2. In the summer, or when sprouts are seen, gardeners should use a potent crabgrass post-emergent herbicide to kill already existing weeds in their lawn. Quinclorac is a good product for this. It should be sprayed on areas where growth is seen. If one has Centipede or St. Augustine grass lawn, they should use a product called Celsius.
Understanding the life cycle of crabgrass is key to eradicating it.
Seeds germinate, and the plant grows during warm months and dies after a frost, all during the same year.
Before dying, the plant produces seeds for the next year, which remain dormant for a short period during cold months and germinate once soil temperatures reach 55-degree F or so. Then the cycle starts again.
In tropical climates, crabgrass may grow as a perennial, flowering and setting seeds all through the year.
Growing a Healthy Lawn
Crabgrass and other weeds will have a difficult time thriving if a lawn is healthy and vigorous. Here gardeners should work in two steps. First, they should eliminate weeds in their entirety. Second, they should make their lawn as healthy as possible to prevent crabgrass seedlings from being able to take root.
When winter is over and the lawn once again comes to life, unfortunately, this is the time for several other things to be reborn. But during this time, i.e., early spring, gardeners can do many things as part of spring lawn maintenance to prevent the emergence of weeds like crabgrass and dandelions, etc.
Springtime Lawn Care
The first thing gardeners will have to do in the early spring is to apply a pre-emergent herbicide to prevent crabgrass from sprouting by killing its seedlings as soon as they germinate. They should read the manufacturer’s instructions carefully before applying the herbicide they choose.
The time to apply the pre-emergent herbicide depends on one’s regional weather. Once the soil temperature rises above 60-degree F, they should apply the herbicide. They should determine this by taking note of the shrubs and trees in their area. Once these trees start budding and blooming, they can use herbicide.
However, gardeners should not use this method if they already have existing crabgrass or have lately laid sod. They should wait for up to four months before reseeding a lawn after applying herbicide. If they’ve newly seeded their lawn, they should wait until they have mowed the grass three times before applying any herbicide.
Herbicides are of two types, including granule and liquid formulas. Gardeners should apply the pre-emergent herbicide evenly across the entire lawn with the help of a spreader. If they use a granule type of herbicide, they should water the grass after the application to enable the active ingredient to penetrate the soil.
Proper Lawn Care for Prevention of Crabgrass
Even though gardeners might have prevented an early infestation of crabgrass by using a pre-emergent herbicide, they need to do several things to their lawn all through the summer months to make sure the grass remains healthy.
A healthy and robust lawn is the best crabgrass preventer.
Lawn Care and Maintenance
Varying weather conditions may result in speeding up or slowing down grass growth. Therefore, gardeners should mow their lawn when needed rather than have a strict schedule. Crabgrass thrives in lots of sunlight, so gardeners should keep their lawns full to prevent crabgrass growth.
They should use a mowing height setting on their lawn mower that is recommended for their particular type of lawn grass, whether it’s Fescue, bluegrass, or any other variety. While mowing, they should not remove more than one-third of the grass blade length.
Gardeners should also water their lawn at irregular intervals, depending upon their current weather. While watering, they should keep long intervals instead of short ones. A well-established lawn needs only around one inch of water per week to develop deeper roots and a healthy lawn.
Eradication of Crabgrass in Small Areas
Organic Weed Killer
A weed killer is the most effective way to kill crabgrass. The market is full of products that contain all-natural ingredients, like acetic acid, clove oil, D-limonene, citric acid, or lemongrass oil, which are still extremely effective in eradicating weeds.
For example, Grass Killer and Natural Armor Weed have all-natural ingredients that are safe around kids and pets. One just has to spray individual weeds, and the product will destroy them.
However, one should also remember that some of these products may kill any grass that comes in contact with them. Hence, they have to make sure they do the job accurately only at overgrown spots.
That said, a selective post-emergent crabgrass killer containing Quinclorac will remove the weed without killing lawn grasses like Zoysia, Fescue, and Bermuda. (But gardeners should not use it on Floratam or St. Augustine).
Another organic weed-killer is corn gluten meal which is produced during the corn milling process and can be used to control crabgrass and other weeds while also providing nutrients to the lawn. To make it effective, gardeners should apply it in the early spring months.
Also, studies show that organic weed-killers work best in warm weather with temperatures above 75° F (24° C), so one should consider waiting for a sunny day to apply an organic herbicide.
For areas in the lawn or flower beds that have only a few crabgrass plants, gardeners can use one of the simplest and most natural ways to kill weeds without killing grass or other plants at the same time. This is also the cheapest method to eradicate unwanted weeds.
If the gardener pours boiling water on a patch of crabgrass, it will stunt the plant and cause it to die soon.
The gardener has to pour the water in a large periphery around the weeds, so the hot water penetrates the entire root system and kills the entire patch effectively.
Gardeners should repeat pouring boiling water daily until the crabgrass is brown and wilted. It’s recommended to pull the roots of the weed out of the ground a few days after the treatment to make sure it doesn’t grow back in the same location.
One need not be surprised to hear that the most popular household cleaning product - vinegar - has great uses in yards, too, as a natural weed-killer.
It can kill any weed, including crabgrass, and needless to say that it’s safe for children and pets. Since it’s mildly acidic, it can kill broadleaf weeds. The best part is that it won’t leave the soil damaged or lifeless as several chemical treatments do.
One just has to soak the entire weed with vinegar. Vinegar has an acidity level of 5% or higher. The results may not be seen immediately, but if the gardener repeats the process several times over a period of up to two weeks, the crabgrass should eventually be seen withered and dead.
To make vinegar even more effective against the weed, gardeners should mix 1 cup of salt for every 1 US gal (3.8 L) of vinegar. The salt will help penetrate the grass and dry it out.
To make vinegar the most effective, gardeners should use it during the hottest time of the day. Once the crabgrass wilts, they should pull it out of the ground entirely to make sure it doesn’t regrow from any remaining healthy roots.
Gardeners should keep in mind that vinegar can kill existing crabgrass, but it can’t prevent new crabgrass from growing. Once the crabgrass withers, they should pull it out of the ground with a shovel or spade.
When all the root system of the weed is removed, gardeners should fill the holes with dirt and sprinkle grass seeds in the area, and water the area to encourage the new grass to grow in the bare spot.
Another household product, baking soda, too can act as a weed killer.
Gardeners should sprinkle baking soda generously onto the weed and around the roots.
Smothering weeds is a good method when large patches of crabgrass are to be eradicated. In smothering, sunlight is blocked, killing the patch in 4-6 weeks.
The gardener should lay large, heavy objects, like bricks or stones, over the crabgrass and leave the patch alone for several weeks. Once the crabgrass dies, the gardener can easily pull it up and replant the grass seed.
Smothering can be done with organic mulch too. This is made of bark or wood chips. Gardeners have to spread a thick layer of organic mulch (around 4 inches (10 cm)). If a gardener lays a mulch made of lawn clippings or leaves, they should add a layer of newspaper on top of crabgrass. This will help smother crabgrass and prevent it from growing back.
Using salt water to kill crabgrass is effective for the weed growing in the cracks of sidewalks, driveways, alongside garages, or any such isolated clumps of weeds.
Gardeners should make a solution of salt and water in a pitcher or watering can. They should then pour this solution directly onto the weeds growing in isolated spots.
This solution can harm other plants, so gardeners should avoid using it in flower beds or lawns.
Citric acid is present in citrus fruits like lemons, oranges, limes, and grapefruits. It can be used to eradicate crabgrass naturally.
Gardeners should mix lemon juice and cider vinegar in a spray bottle and shake well. Then they should spray it onto the crabgrass on a hot, sunny day with little wind.
By putting the nozzle onto the stream setting, they can avoid spraying on the desired plants nearby. If the plants don’t die within a week, they should repeat spraying one more time.
How to Remove Stubborn Crabgrass?
If the gardener tries every method, but crabgrass still grows in their garden, they can use big guns and try a conventional herbicide.
Herbicides are either selective or non-selective. Non-selective ones kill everything that comes in contact with them, including gardeners’ favorite plants and lawn grass, whereas selective ones are specifically designed to target selected plants like broadleaf weeds.
For crabgrass, gardeners should choose a selective post-emergent herbicide to eradicate the weed without damaging their grass. They should check the product label for information about approved grass types.
Certain grass types, such as centipede grass and St. Augustine, are susceptible to some herbicides that other grasses are not.
Gardeners should take care while applying the herbicide in their garden to wear rubber boots to prevent their legs and feet from getting soaked in the herbicide solution.
Depending on the product, gardeners should spray the herbicide directly on the crabgrass or across the yard in a thin line. They should make sure the day they choose for this chore should not be windy, otherwise, the spray may travel with the wind to spread on other plants.
Children and pets should be kept away from the yard and the herbicides. Gardeners should check the product label to find out the amount of time required for kids and pets to play safely in the yard after the herbicide application.
Preventing Crabgrass in a Natural Way
Once the gardener gets rid of crabgrass, the next step logically is prevention. The key to preventing another crabgrass attack is to create lawn conditions that will stop the weed from germinating and growing in the first place.
Strategic Watering to Kill Crabgrass but Save the Lawn
Crabgrass and some other similar weeds love water, and they grow well when watered often. The best way to discourage crabgrass from coming back is to make sure the lawn is healthy and thick.
To boost healthy grass growth while stunting these weeds with shallow roots, one has to water less frequently but in a heavier quantity.
This will help the lawn grass thrive, and weeds struggle and eventually die out. A once-a-week watering boosts deep root growth, while frequent short waterings help grow shallow roots.
Running an Aerator
An aerator helps loosen the soil and thus prevents crabgrass. Crabgrass loves dense, compact soil. If one is constantly dealing with crabgrass, one should consider renting or buying an aerator.
Aerating one’s lawn forms tiny holes in the soil and thus loosens it up and helps one’s lawn grass grow deeper. Aerating creates holes in the soil, but it won’t tear up one’s grass off their existing lawn.
Solarizing the Soil
A good thing about solarizing is that it can be done in any season but is more effective in the hottest months. Here’s how to do it:
- The gardener should first mow the lawn to a very short length
- Then, they should water the area profusely to saturate the soil and grass.
- Now, they should cover the ground with a transparent plastic sheet. They should make sure to use clear plastic to let sufficient sunlight in.
- Then, they should bury the borders of the plastic sheet in the ground and thus seal the edges.
- This covering should be left in place for up to 6 weeks. This will allow the heat and steam to build up inside and kill the weeds and seeds.
- When the gardener starts seeing less steam, they can remove the plastic cover.
Fill Empty Areas
Crabgrass tends to grow in bare dirt patches. If a gardener notices any parts of their lawn looking thin or bare, they should buy some grass seed and seed the area in the fall or spring.
As the new grass grows, it will compete with the crabgrass and probably will overtake the area.
If you’re in the hottest part of summer, consider waiting till the weather cools down before overseeding.
Crabgrass tends to germinate quickly if the lawn is not densely shaded. A thick and healthy lawn will protect the area against crabgrass.
Gardeners should plant during fall for healthy grass growth and overseed thinner areas. When colder weather arrives, the freezing temperature can kill crabgrass seedlings.
Gardeners should water their yards deeply but infrequently. The turf grass can quickly revive from a brief drought, but dry soil is not kind to crabgrass roots. This trick causes the crabgrass to deteriorate but causes no long-term harm to the lawn.
Avoid Mowing Too Short
Normally gardeners tend to cut the lawn grass quite short so they won’t have to cut it again soon. This method surely saves gardeners’ time and energy.
However, it also creates lawn conditions that are the most favorable for weed growth. This is because when the grass is short, weeds receive more sunlight and get more space to spread their roots and invade.
To avoid this situation, gardeners should keep their lawn fairly tall and try not to cut more than 1/3 of the blades at a time. Ideally, they should keep their height above 2 inches (5.1 cm), particularly during warm weather.
Overseeding to Crowd Out Crabgrass
“Overseeding” is a great method for preventing crabgrass growth. Gardeners should plant excessive grass seeds on their lawn in the spring, so their grass sucks up all the nutrients in the soil and crowds out any growing weeds.
Failing to weed often enables patches of weeds to thrive, bloom, spread their seeds, and ultimately take over one’s lawn. Frequent weeding keeps weeds young and manageable, making them able to be pulled easily.
Most weeds can be tackled easily, but crabgrass is a weed that is extremely invasive and quick-spreading. It’s essential to nip crabgrass in the bud to keep one’s lawn beautiful and pristine.
Although weeding is a task that takes a lot of time and energy, the results are definitely rewarding when one sees the beauty of their lawn and feels proud.
Reduce Seed Production
Gardeners should pull out as many plants as they can early in the season before they can set seed. Mowing can offer them time to remove plants.
If they have to deal with large patches, they can naturally kill midsummer weeds with herbicide containing ingredients like citric acid and clove oil. However, they should use it very carefully as it will kill any plant it touches, including the lawn grass.
Reduce Seed Distribution
The main strength of crabgrass is the aggressive seed distribution that lets it spread through a big area fast and overtake one’s lawn. Therefore, preventing its seed distribution is one of the best ways to eradicate crabgrass without using chemicals.
For this, when the gardener hand-pull grass patches, they should place them in a plastic bag and throw away those bags immediately into trash bins or landfill. This prevents seeds from getting dispersed on the lawn.
If the gardener composts all the organic material, they can even tie up the bags and leave them out in the sun for 4 to 6 weeks. This way, the seeds are killed by the heat, and their remnants are safe to add to the compost heap.
Autumn Lawn Care
While the cooling temperatures and shorter days may induce one’s lawn to slow down and stop its growth for the coming winter months, the gardener still has a job to do when it comes to lawn care to make sure it’s healthy and prevents future crabgrass growth.
It may seem as if the gardener’s lawn grass has stopped growing, but actually, it won’t stop until the first frost of winter. Gardeners should continue mowing the lawn as required during this period to maintain a proper and healthy length of grass blades. During the autumn months, evaporation reduces, and so the lawn will perhaps not need much irrigation.
However, gardeners should keep an eye on the amount of water the grass receives.
They should make sure to rake the lawn regularly during the autumn months. Falling leaves that cover the grass will block out the sun rays that the grass needs for food, and damp leaves (fallen) may promote fungal growth.
Summer months can be hard on grass and soil because of heat stress and compacted soil. Therefore, autumn is the best time to aerate the lawn. It will remove soil plugs from the lawn, which will free up passageways, enabling nutrients to reach the grassroots.
Aerating in the fall makes sure one’s lawn has healthy growth the next growing season. This is also a great time to fertilize the lawn to ensure the grass receives proper nutrients all through the winter months and produce a healthier lawn following spring. Gardeners can also use this time to do any reseeding of bare spots in the yard.
Using pre-emergent herbicides to stop crabgrass from germinating and removing crabgrass using a natural weed-killer or post-emergent herbicides eliminates those unwanted intruders from one’s lawn.
Using proper lawn mowing methods and providing one’s lawn with the right nourishment and nutrients it needs can help control crabgrass and keep it at bay from overtaking one’s lawn next year and even years to come.
But even if one doesn’t succeed in controlling it in August, they should not be worried because crabgrass will be dead at the first frost, anyhow, as it’s an annual grass.