If you want to get rid of crabgrass, you’ll need to attack this pervasive weed from many angles. This article will teach you how to treat existing crabgrass using conventional and organic methods and discuss lawn care techniques that help prevent infestations in the future. Employing these techniques over time will help reduce crabgrass in your lawn.
What is crabgrass?
Crabgrass is a flat, annual weed that thrives in hot weather. As an annual summer weed, crabgrass germinates in spring, matures during the warm season, and dies at the first frost. As it grows, crabgrass puts out branches, or tillers, that look like crab legs, hence its name.
If left to seed, each crabgrass plant produces around 150,000 seeds that will lie dormant until temperatures warm up again next spring. Then, the process begins again.
Crabgrass favors thin turf or turf with areas of bare soil. It is common to see crabgrass along sidewalks as well. The soil along paved areas tends to be shallow, thin, or of poor quality, which invites crabgrass to grow. Finally, if your turf becomes less competitive during the hottest part of the year, this may also provide an easy foothold for this weed.
Treat existing crabgrass in the lawn
If you are reading this article, you likely already have crabgrass in your lawn. If you are trying to get crabgrass to exit your lawn pronto, here are a few natural weed-control methods to consider.
1. Remove crabgrass by hand
If you have a small area with crabgrass, weeding by hand is an obvious but effective method. Use a screwdriver or weed puller to remove the crabgrass plant and the root from the soil. Put the weeds in a trash bag so that seeds can’t settle back into the lawn.
Before you grab the bottle of vinegar from your pantry to get rid of crabgrass in your yard, you need to know a few things. Household vinegar (5% acetic acid) may be effective for very young crabgrass, but expect to spray the small weeds two or three times for best results.
If you want a higher rate of success, consider a horticultural vinegar with 20% acetic acid. As with household vinegar, horticultural vinegar is most effective on crabgrass if used early and often. Horticultural vinegar damages the cell walls of the weeds. The weeds then lose water, dry up, and eventually die.
Spraying crabgrass seedlings within two weeks of germination yields the best results. One application may be sufficient for very young plants. For slightly older crabgrass, you may need to apply two or three times for best results.
Vinegar is nonselective, meaning that it will damage any plant tissue it comes in contact with. So, spray accurately for best results.
A note on safety: Homeowners are advised that even “natural” products can pose safety hazards if not used per the manufacturer’s instructions. Acetic acid at high concentrations can burn the skin or eyes causing permanent damage, even blindness. Always follow the instructions on the label for safety and maximum effectiveness.
Steam and boiling water can be effective in the fight against crabgrass. Large organizations use commercial steam equipment to accomplish this task, but homeowners usually boil the water in a tea kettle or pot. Pour the boiling water over the plant and then wait a week or so until it is brown.
One creative homeowner used an indoor steam cleaning machine and successfully rid a brick driveway of its pesky weeds (including crabgrass). Wait four to five days to see the weeds fully die and then remove by hand.
As with most non-chemical methods, repeated applications are needed. This method is also nonselective and will kill any plant tissue it contacts.
4. Store-bought products
If you go to your local home improvement store, you will find a plethora of organic weed sprays and conventional, post-emergent herbicides. (Note: If you are looking for a product that is approved for organic production, look for the OMRI label.)
Active ingredients in natural and OMRI-certified products include:
- Caprylic acid
- Citric acid
- D-limonene (citrus oil)
- Ammonium nonanoate
In addition to the well-known glyphosate, there are many other active ingredients in conventional, post-emergent crabgrass killers. Many are specifically marketed as crabgrass treatment or prevention on the front of the product. Some products only target broadleaf weeds like dandelions, for example, so be sure your product is effective on grassy weeds such as crabgrass.
Whether you choose natural or conventional formulas, store-bought products are often considered an easy, convenient method of control for existing weeds or weeds that pop up during the growing season.
5. Sun/air deprivation
A final option is to smother the weeds. You can use spare bricks or cardboard to prevent sunlight and air from reaching the weed, thereby killing it.
Prevent crabgrass in the future
To prevent crabgrass in the future, consider pre-emergents and follow a few, common-sense maintenance practices. The idea is that a healthy lawn prevents weeds by providing competition and depriving the crabgrass of light and space. Follow these basic lawn care maintenance tips to increase the health (and decrease the crabgrass) in your lawn.
Use a pre-emergent
Crabgrass seeds start to emerge in early spring when the soil temperature reaches 55 degrees for several days in a row. Pre-emergent herbicides (also called crabgrass preventers) kill the crabgrass roots as they reach the top of the soil.
There are numerous conventional options at your local home improvement store, most in granular form. Corn gluten meal is a popular non-chemical pre-emergent, though experts are divided on its efficacy.
When choosing a pre-emergent, be sure to select a product that is designed for grassy weeds, such as crabgrass. Some pre-emergents work for broadleaf weeds only while other products work for both types.
Most products can be used anywhere on the lawn or in flower beds. Most are granular, so use a spreader to apply the granules and then water them in. This is general guidance; check the label on your product for specific instructions.
If you choose to use a pre-emergent, be sure to time it just right. Contact your local Extension Service for information on when to apply pre-emergents in your area.
Mow at the right height
Mow at the highest level recommended for your grass type. Experts recommend letting it grow to at least 3 inches. When it is time to mow, follow the one-third rule: Never remove more than one-third of the grass blades at one time.
The idea behind this is that a tall lawn will keep the soil floor shaded, which means that the crabgrass will not have the light it needs to grow. Crabgrass will not tolerate shade, so keeping the grass tall lets the grass do some of the preventive work for you.
Finally, if your crabgrass has already gone to seed, be sure to bag your grass clippings and dispose of them in the trash. If you leave the clippings on the ground, you will be re-seeding a new generation of crabgrass on your lawn!
Water deeply and infrequently to encourage roots to grow deeply. Whether you water by hand or rely on your sprinkler system, aim for about 1 inch of water once per week.
Dethatch and aerate
Compaction can happen all too easily in a home lawn, so in most cases, dethatching and aeration are necessary lawn maintenance chores. Soil compaction can contribute to a thin turf and a weed-friendly environment. Dethatching means that you remove the thatch from the lawn so water, air, and fertilizer can reach the soil. Aeration is when you pull plugs from the soil to allow more water and air to reach below the soil at the root level.
Be sure to use these two practices in conjunction with overseeding. Aeration can bring weed seeds to the surface, so you’ll want to be sure that you overseed to fill in the lawn with nice, thick grass which provides competition and shade for crabgrass seeds.
Fertilize your lawn to keep everything in top shape. First, get a soil test to determine the condition of your soil and what nutrients it may need. Then, purchase an appropriate conventional or organic fertilizer to keep your lawn full and thick.
Fill in the bare patches
As we’ve mentioned, overseeding is key to providing the maximum level of crabgrass competition. After you remove existing crabgrass, you’ll want to overseed those areas to help new grass to grow. Bare spots create a perfect void for new crabgrass plants to sprout.
Many experts emphasize the fact that a full, dense lawn is key for inhibiting crabgrass germination. Remember, crabgrass thrives in the sun and dies in the shade. Let your lawn do some of the work for you — make sure the grass is thick and thriving and it will prevent new weeds from sprouting.
Crabgrass control is an ongoing endeavor. Crabgrass seeds in the soil can stay dormant for several years, so expect to repeat this process annually. Persistence is key to reducing your crabgrass population over time.
Crabgrass is a persistent, pesky lawn weed but you can use natural and conventional methods to eliminate existing crabgrass and prevent it from being a problem in the future. Above all, be persistent, and don’t underestimate the power of simple, routine landscaping practices to aid you in the fight against this weed.
If crabgrass is too much for your to-do list, contact a local professional to conquer your crabgrass and restore your lawn.
Main Photo Credit: Rasbak | Wikimedia Commons | CC BY-SA 3.0