When To Treat Crabgrass

Apr 23, 2019
Sue Kelly April 24, 2019
Nancy Sinnen
Customer Service Representative
Lawn & Garden Expert

Feeding and Managing Pregnant Mares

Crabgrass seeds begin to sprout in mid-spring, as soon as the soil temperature reaches 55 degrees. It will quickly become a problem during the summer because it is able to vigorously grow in hot, dry conditions. It thrives in thin and bare spots in your lawn and before it dies in the fall, a single crabgrass plant will produce thousands of seeds that can germinate the following spring. 

Every spring, Minnesota has a short window of opportunity to apply crabgrass pre-emergent. Treating crabgrass during this time is the most effective. Herbicides that are labeled as a pre-emergent will prevent seeds from being able to complete the germination process. It works when a sprouting seed comes in contact with the herbicide so make sure your have your pre-emergent freshly applied before your soils reaches 55 degrees. A good indicator that we tell our customers that will let them know it is too late to apply pre-emergent is when the lilacs bloom.

The product we recommend is Scotts Turf Builder Halts Crabgrass Preventer with Lawn Food. This is a dry granular that is broadcasted and then watered into the top one-inch of the soil. 

The most important reason crabgrass is best prevented in our short window during early spring is because the only kind of post-emergent herbicide that will kill crabgrass will also kill your lawn. If You have a manageable amount of crabgrass then you are able to spot treat it with glyphosate products such as Round Up or Killall.


There are a few other things you can do to prevent crabgrass:

  • Mow at the proper height. Mowing higher, usually the top two settings on your mower, allows taller grass blades to shade the soil, which will also help prevent the germination of crabgrass seeds. 
  • Feed regularly. A thick, full lawn rarely contains much crabgrass. When your lawn is stressed out it, it has a greater chance of being taken over by weeds. Feeding your lawn regularly, every 6 to 8 weeks, during the growing season helps you lawn stay thick and lush. 
  • Deep water your lawn. Shallow, frequent water encourages shallow root growth, making the grass more likely to suffer during periods of heat and rout. That will lead to thin patches and bare spots that crabgrass will take advantage of. 
  • Repair lawn damage. Crabgrass plants will be killed by frost in the fall leaving bare spots. All you need to do is repair the bare spots to keep new weeds out and ensure it is watered until the new grass is established.
  • Be sure to stop into our Waconia or Maple Plain locations to pick up your crabgrass preventing herbicide soon before it is too late! 


Filed Under: Lawn & Garden