Are you tired of using one herbicide after another just to have the pernicious weed show up again and again? Do you feel like you’ve tried every possible crabgrass herbicide under the sun? In this article, we’ll discuss a variety of techniques dealing with how to kill crabgrass in lawns.
Healthy Lawn = Best Crabgrass Killer
The best way to not have crabgrass in your lawn is to have a healthy lawn that can easily compete for sunlight, water and soil nutrients. Healthy grass smothers a crabgrass seedling and prevents it from being able to establish itself. If crabgrass doesn’t have anywhere it can gain a toehold in your lawn, it can’t grow well enough to drive out your desired grass. By regularly aerating, fertilizing, dethaching, cutting and irrigating your lawn to keep it performing at its best and dealing with pest problems as soon as they are apparent, you’ll find your lawn is much easier to maintain.
There are a number of options available for treatment, but one of the fastest ways to start dealing with crabgrass that has invaded your lawn is by using a chemical herbicide. But don’t just grab the closest bottle to hand! There are many herbicide crabgrass killer that have a variety of actions. In addition, the kind you need to get the job done will depend on a large number of factors. There is no single best crabgrass killer for lawns! Though there are many more categories that herbicides can be classified by, these are the broadest categories. Let’s take a look at what better living through chemistry has to offer us. This leads us to:
Pre-Emergent vs. Post Emergent
A pre-emergent herbicide acts by preventing a particular enzyme to function in the germinating seed, preventing it from growing further to become a seedling. This is a great herbicide to use, but it must be applied at specific times during the year, usually after a certain number of days at a certain high temperature range. Outside of this timeframe, applying a pre-emergent herbicide won’t do you any good. Because crabgrass germinates when the soil temperature 1-2″ down reaches 62 degrees F for a few days, treating your lawn just after your local area gets four days with daily highs between 65-70 degrees F. Barricade is considered the best crabgrass killer in this class of herbicide.
A post emergent herbicide is applied after the weed has begun growing or has become established. Because it has a much longer range of time where it is effective, it can be used through the rest of the season to take care of crabgrass that you couldn’t get to with a pre-emergent herbicide. Its main limitation is that the crabgrass must be growing when treated and it is much more effective on smaller rather than larger plants. Unfortunately, post emergent herbicides are not terribly effective against established crabgrass because the plants are otherwise so hardy. Drive XLR8 is probably the best post emergent crabgrass killer because it can be used on a variety of cool season grasses and is less problematic than other crab grass killer in this class, as well as working on larger crabgrass plants. Unfortunately, its use is restricted in some states, where the similar Acclaim Extra can be used without a class, licensing or certification process.
Contact vs. Systemic
A contact herbicide is one that poisons the plant where they have contact with each other. They have a variety of effects, from breaking down chlorophyll and the photosynthesis process in those areas, essentially starving the plant, to causing unregulated and abnormal growth by applying plant hormones, causing it to strangle itself by reducing nutrient flow. Contact herbicides work very quickly, and you’ll often see differences between morning and evening or over a few days, but only to the parts of the plant that was treated, leaving underground roots and untouched greenery behind if not treated and potential that you’ll need to retreat them. RoundUp is probably the most commonly used contact crab grass killer on the market.
Systemic herbicides take longer to take effect, but they affect the entire plant. Though it takes longer, it’s more likely to finish the job the first time. You’ll have to tolerate the crabgrass longer, but it’s far less likely to come back after treatment. It can take several weeks to reach full effect. Tenacity is a systemic herbicide commonly used in crabgrass control.
Selective vs. Non-Selective
A selective herbicide is an herbicide that only damage particular plants, such as grasses and grassy weeds. This means it is safe if you’re trying to remove crabgrass from a flower bed where the desired plants are dicots instead of grasses. As an example, selective herbicides for grasses cause a particular hormone only found in grasses to be bound up or stop production, but because that hormone is not found in dicots, it does not cause problems for those plants.Drive XLR8, mentioned above as a post emergent herbicide, is a selective crab grass killer.
A non-selective herbicide is a general herbicide and can kill a wide variety of plants, including nearby landscaping plants, flowers, the turf you’re trying to nurse back to health and similar plants that you’d rather preserve. Though they are quite effective, you need to be extremely careful that you don’t damage surrounding desired plants that will leave another compromised area in your lawn for more crabgrass to sneak in. Roundup, mentioned above, is a non-selective herbicide that is very popular with homeowners.
Easy on Mother Earth
If you prefer to look at more earth friendly options, there are a few available. But first, let’s talk about the difference between natural and organic. A natural crabgrass killer will not use chemicals or materials that are not biodegradable. An organic crabgrass killer, on the other hand, doesn’t use chemicals either, but will often use non-natural products such as black plastic mulch in a garden to kill weed seeds and smother crabgrass plants.
Natural Crabgrass Control Methods
As was mentioned at the beginning, the best crabgrass control is having a healthy, well-established lawn. By fertilizing in the spring and fall, with a heavier fall application, your cool season grasses will be able to grow well enough to smother out any crabgrass seedlings that are able to get started. Maintaining your lawn by immediately filling any bare spots will help keep crabgrass at bay.
Because crabgrass has shallow roots, irrigating with more water less frequently will provide plenty of water for your desired grass while depriving crabgrass of the water it needs. These shorter roots also help make hand weeding work well as a control method. Watering the lawn before hand weeding makes it much easier to get up as much of the plant as possible.
Proper mowing technique is one of the most effective weed control methods available. According to a report from Michigan State University, proper mowing will control not only crabgrass but 80 additional weed species as well. Leave more grass on your lawn, to a height of 2.5-3″, to provide the best photosynthesis for your existing grass plants and keep the shorter crabgrass from getting the sunlight it needs for growth. Removing crabgrass seed in plant cuttings by hot composting it to kill the seed or by raking it off later in the season will help reduce your seed bank for next year. Avoid raking in the spring, as that will just bring more crabgrass up to the surface to cause more problems in your lawn.
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. Because ice forms as a purer water, it removes the extra water from the solution. You should remove anywhere from 10-25% of the water content to create a solution strong enough to act as a crab grass killer.
Now that you know the best options in controlling crab grass, why not begin formulating your battle plan? It won’t be long before having the proper pre-emergents in place will help keep your beautiful lawn looking fabulous and free of pesky crabgrass. Gather what you need and plan your attack today!