Crabgrass Killer

About Crabgrass Killer

Crabgrass can be controlled before and after it emerges from seeds underground, using products called crabgrass pre-emergent and crabgrass post-emergent herbicides. They both work in different ways with different active ingredients, and your best bet for the most thorough control is to use them both. It is important to realize that a few crabgrass weeds here and there isn’t the end of the world, and that total control is very difficult. Here is some information on both types, which will let you choose the best type for your yard. Take a look at our lawn care schedule to know when to apply these products.

• Pre-Emergent Crabgrass Herbicides: These products are a great choice because they will prevent any crabgrass from emerging above the ground, killing them before they become an unsightly problem. The key with post emergent herbicides is all about timing. They must be applied before the crabgrass seeds germinate, in early spring. There is less of a risk in misusing a pre-emergent crabgrass herbicide, and less of a chance of damaging or killing existing grass.
• Post-Emergent Crabgrass Herbicides: Post-emergent crabgrass killers are what most of us are more familiar with. Applied to existing crabgrass in your yard, these products will kill young crabgrass weeds, but are less effective on older, larger, more established weeds. They are widely available and proven to be effective, but there are more variables to success.

Crabgrass Killer Resources

*See our article How to Get Rid of Crabgrass for complete crabgrass control steps.

How To Get Rid Of Crabgrass

Crabgrass killers are not difficult to use, as long as you follow all label directions and safety warnings carefully. Here are some things to keep in mind when using pre-emergent and post emergent crabgrass killers:

• Pre-emergent herbicides must be used at the proper time. This means before the weed seed has been allowed to grow, which will be in early spring. They can be applied once the soil temperature reaches 55 degrees for three consecutive days.
• Post-emergent herbicides should be applied when temperatures are below 85 degrees, and on a low humidity day.
• Pre-emergents should be watered in. After applying a post-emergent, do not water or mow the treated areas for at least 24 hours.
• Some pre-emergent crabgrass products are combined with a fertilizer and are commonly known as weed and feed products. Since most lawns often do not need fertilizer in the spring, aim for a fertilizer-free product or one with slow-releasing nitrogen.
• Post-emergent herbicide products are often labeled for use on specific types of turf grass, and each product will work on different grasses. Check the label carefully to avoid using the wrong product.
• If you use a pre-emergent and still see some crabgrass, try to target the weeds early with a post-emergent product. If crabgrass is persistent into mid-July, even a post-emergent product will likely be ineffective. Keep in mind that these weeds will die with the first frost, so it is best to wait it out.