Crabgrass Weed Killer: FAQs and best weed killers

What is crabgrass?

Crabgrass is a species belonging to the Digitaria genus and a grass variety known for its fast-spreading rate over any nutrition-deficit, arid land, causing enormous damage to crop plants. Their popular worldwide name finger-grass is owed to their characteristic finger-like inflorescences. This lawn pest is native to the tropics however can grow comfortably in all other temperature zones. While this grass is undesirable for farmers, certain fonio species find extensive use in various parts of the world. For example, the plant serves as a source of nutrient-rich forage for cattle. Apart from this, it is also used in flour, porridge, and the manufacture of beer.

Why don’t we like crabgrass?

This weed crop can produce up to 150,000 seeds in a season and thus take over vast stretches of land within short periods. This is an annual herb and grows during the spring season. When the leaves decay during fall, large cavities are formed in the field that becomes the spaces for crabgrass seeds to germinate in the next season. Hence, it becomes difficult to control this weed if not checked at their primary stage of appearance on the field. They threaten the survival of desired crop plants on the lawn.

How to kill crabgrass?

The options to combat crabgrass are manual de-weeding, herbicides (post-emergent and pre-emergent killers), and homemade herbicidal agents. Among these, the herbicidal agents (artificial and homemade) are most widely preferred. During the initial stages, homemade herbicides are the most widespread choice and adequately sufficient while imparting less damage to the soil, your environment, and humans in contact with the lawn. But after a certain point of growth, only artificial herbicides are effective in the eradication of crabgrass.

What is the best crabgrass killer?

The best choice in the permanent eradication of crabgrass would be any herbicide containing the chemical Quinclorac. The best way to control crabgrass is by preventing it from flowering or preventing its recurrence altogether. Post-emergent and pre-emergent killers can do this. Whether it’s a post or pre-emergent killer, if the crabgrass has matured, none of the chemicals are effective. Hence, the best application time is either before germination or right after seed germination when the crabgrass is still weak.

Post-emergent crabgrass killer

Post-emergent crabgrass killers are effective until crabgrass is still in its initial growth stage with fewer shoots. This process loses efficiency as the plant tillers and multiple sessions are required to suppress the weed. The popular post-emergent crabgrass killers are Quinclorac, Fenoxaprop-ethyl, and Mesotrion that can control crabgrass growth and eradicate it completely with spaced application of two to three weeks. Quinclorac is the best agent for all species of crabgrass at all growing phases and is less harmful to crop plants. Fenoxaprop-ethyl is usually preferred before tillering has occurred but is highly effective against other grasses that quinclorac cannot combat. Mesotrione is another excellent choice as a postemergence crabgrass killer in its initial stages of growth.

Pre-emergent crabgrass killer

The best way to eradicate crabgrass is by preventing its emergence using an effective pre-emergent killer. This application should ideally be done just before the new seed germination season of crabgrass. Pre-emergent killers are sprayed as their aqueous mixture into the voids on the field where the crabgrass seeds are present. Once the seeds germinate, pre-emergent killers are seldom effective.

Manually removing crabgrass

Right after the germination season when the crabgrass is still in its nascent stage of growth and weak in nature, manual de-weeding is effective using a sharp knife. But make sure to uproot it from its root and not spill any seeds on the field during manual uprooting.

Using homemade weed killer on crabgrass

Homemade remedies are very much effective in eradication right after germination when the weed is still immature. The most common materials in use are salt, vinegar, vinegar, bleach, boiling water, and cornmeal. Salt – Table salt can be directly sprinkled onto the roots or sprayed in a 1:1 ratio with hot water as part of a continuous schedule. This method is quite effective but the disadvantage is that the strong salt solution may affect the healthy crops or accumulate in the soil, posing a threat to future crops. Vinegar – The acetic acid in vinegar acts as a desiccant, killing leaves faster than the salt solution. Usually, a 5 parts diluted vinegar is used as stronger vinegar has the potential of burning the skin. But the stronger the concentration, the more effective it is against leaves (vinegar seldom affects roots). Be careful about not pouring it into crop plants. Bleach – Bleach burns leaves like vinegar and is a popular herbicide. However, its extreme alkalinity can not only harm the skin but also healthy crop plants on careless handling. Moreover, frequent bleach application severely hampers soil health as well. Boiling hot water – This method instantly cooks off leaves and delicate parts and is more effective when combined with salts. Boiling water may also harm surrounding crop plants or injure the skin. Cornmeal – Cornmeal is an ideal pre-emergent homemade weed killer as it prevents root formation even if seeds germinate. There are no major side effects other than allergic reactions for some individuals from gluten.


Crabgrass is one of the worst nightmares for any gardener, primarily because of its rate of spreading across a large lawn. This annual plant is called by different names worldwide like fonio and finger-grass. Combating this lawn pest is a tedious job and needs powerful tactics and constant monitoring. Ideally, prevention using pre-emergent killers is the best method that is used before the germinating season. If the seeds have already germinated but seedlings are weak and immature, post-emergent killers are effective. On gaining full maturity, no method is 100% effective and the weed spreads rapidly producing 150,000 seeds in a season. Homemade remedies are also effective but are non-specific and can damage crops too.

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