Ants are usually harmless to plants, but some ants, like pavement ants and cornfield ants, will injure them. If you notice that your plants are beginning to wither and you see ants surrounding your plants or going in and out of the dirt near its base, perhaps it is the ants that are causing the problem. Fortunately, there are several methods that can kill the ants in your plant roots and if one method does not work well for you, try another.
Apply a pesticide to the ant mounds around your plants. This can be a dust or spray pesticide and should be labeled to kill ants in the outdoors. Examples include Sevin and Ficam. Adhere to the label instructions for any pesticides used.
Take container plants out of the pots, if applicable. Shake off the excess dirt outdoors away from your home. Then take your root ball and soak it in water for two days and clean out your container. Repot with fresh potting soil.
Stick ant baits into the soil around your plants. You can also stick ant baits in potted plants. The ants are supposed to take the poisonous material in the trap back to the colony and hopefully kill the queen.
Spread organic material around the base of your plants. According to the Michigan State University extension, red chili peppers, paprika, dried peppermint and cream of tartar are alternatives to using pesticides to get rid of ants.