The common violet (Viola sororia), also called the blue violet and the sand violet, grows best in U.S. Department of Agriculture's plant hardiness zones 3 through 9. Most homeowners consider the violet a nuisance weed, even though it is really a perennial flower. You can easily identify a violet by its heart-shaped leaves, and blue or violet-colored flowers. Unfortunately, violets are stubborn and hard to eliminate. It can be done, however, with hard work and perseverance.
Put on garden gloves, and pull the violets out. This is only a good option if you have a small patch of violets to get rid of. If the roots don't come up when you pull, use a garden shovel to dig them out.
Mix a spreader-sticker with an herbicide that contains the main ingredient triclopyr. The University of Nebraska–Lincoln Extension recommends this because the foliage of the violets is waxy. The spreader-sticker is an additive that is necessary to keep the triclopyr from dripping off of the foliage, which would prevent it from being adequately absorbed. Use at a rate of 1 tablespoon of spreader-sticker for every gallon of herbicide.
Spray the herbicide directly on the violet patches that are too big to pull-out by hand. The violets should be soaked with the herbicide following the specific instructions on the product label. This is best done in the fall before the plants begin to winter.
Repeat the use of the herbicide 10 to 14 days later.
Plant new flowers or grass seed in the empty patch of soil so no new violets can grow back in that area. Your goal should be to develop a healthy lawn that chokes out any future violet plants.