When to treat lawn for Wild Violets

Asked August 24, 2019, 1:36 PM EDT

What month is the best month of the year in Minnesota for treating lawns for wild violets?

Hennepin County Minnesota

1 Response

Thanks for the question.

Wild violet is a tough to control perennial weed that will just keep on giving if nothing is done to control it. Fall is the best time of year to attack it. As is true for many weeds, this is when wild violets are transporting everything down to their roots to store for the next growing season. Consequently, any applied herbicide is quickly distributed throughout the plant. They can self-seed but can also grow from underground roots called rhizomes. Violets when they first germinate (spring) are relatively easy to pull out. More established violets (three or four years) are very difficult to remove with all of their root systems.

My suggestion would be to wait another couple of weeks (till mid-September) and then apply a broadleaf herbicide that contains 2,4-D or Dicamba (look for either one on the herbicide label). Both chemicals will selectively kill violets without damaging your grass. In your application it will be very important that you abide by all the precautions on the label. Be sure to check the herbicide label to be sure that it is effective against wild violets.

On a broader note, the best way to combat wild violets and most other weeds is to grow a dense lawn with little to no room for weeds. While there are many ways to achieve this, one of the simplest is to adjust the cutting-height of your mower. Most folks, unfortunately, cut their grass way too short. All this does is to encourage further root development of any weeds that may be present. A turf height of 2.5 to 3 inches is ideal. Typically, this is a “notch” or two below the highest cut level on your power mower. The objective is to have a healthy looking yard and not a putting green.

Here are some other publications that can give you further information:

https://apps.extension.umn.edu/garden/diagnose/weed/idlist.html#CBViolet

https://byf.unl.edu/wild-violet-control

https://extension.umd.edu/hgic/topics/wild-violet

Good Luck!!