How to get rid of crabgrass
Crabgrass is an annual warm-season weed that produces by seed. If not attended to properly, crabgrass will take over the entire area. It spreads quickly but you can remove it and prevent it from coming back.
To rid your lawn of crabgrass, apply a preemergent herbicide at the right time to kill the crabgrass. When the soil temperature reaches 55 to 60 degrees Fahrenheit (at a depth of 2 – 3-inches), the first crabgrass seed will germinate. Crab grass will produce seed from mid-summer to fall. The autumn frosts will kill the crabgrass plants but not the seeds.
A preemergent herbicide can be either granular or liquid and kills the crabgrass seedlings as they germinate, before they emerge – stopping crabgrass in its tracks. If you aerate your lawn, do it beforehand – you don’t want to break this “invisible shield” that the herbicide has. Preemergent herbicides need to be applied before germination – but not too far ahead.
Certain “weed and feed” products often contain preemergent herbicides, but some wonder if the concentration is strong enough to be effective. You may want to use something like Dimension and Tupersan. Since not all crabgrass seeds germinate at once, a product like Dimension will kill later-germinating crabgrass as well. It is also a bit effective as a post emergent herbicide. Tupersan will not damage germinating lawn grass seed. Its’ active ingredient is Siduron which is often combined with starter fertilizers. For newly-seeded lawns, wait until after 3 mowings (or 3 months to be safe) before applying preemergent herbicides.
Tips on using preemergent herbicides:
Since water activates preemergent pesticides, irrigate afterwards.
Since all crabgrass seedlings do not germinate at once, re-apply to kill the later germinating crabgrass.
As with any chemicals – read the directions on the label, measure your lawn and calibrate your spreader carefully.
Don’t aerate the lawn after applying preemergent herbicide.
Don’t apply preemergent herbicides on new sod.
There are post emergent herbicides that will kill crabgrass as well but these will only kill young crabgrass plants making post emergent herbicides not as effective as preemergent herbicides.
If you don’t want to use chemicals for crabgrass control there are a few things you can do to keep a healthy lawn:
Fertilize more heavily in the autumn than in the spring. In autumn the frosts have killed any crabgrass.
Don’t allow bare spots to remain uncovered for long – it’s an open invitation for crabgrass to take over. In fall, overseed those bare spots.
Water your lawn more deeply and less frequently. Crab grass is a shallow weed.
Set your lawn mower on “high” (2 ½ to 3 inches) to allow the lawn to protect its own turf better by depriving crabgrass seeds of the light they need to germinate.
Organic?? Corn gluten is a great weed and feed product. An organic preemergent herbicide with corn gluten will suppress crab crabgrass germination and fertilize your lawn. And good old-fashioned weeding is also another method. If there are many to pull, wet the lawn to make it easier to dig them out.
In closing:
Do not mow the lawn too short – longer grass smothers the crab grass.
Fertilize your lawn at the recommended times.
Crabgrass roots move quickly and will take over your lawn, so tackle the problem at first sight.
Apply corn gluten to your lawn in the early spring months.
Pull crabgrass by its roots to stop germinating.
Want the best looking lawn in the neighborhood? Learn how to properly care for your lawn – just click here.


