There are two ways to deal with ants on peonies. The most effective way of getting rid of ants in potted plants is a combination of baiting and using insecticidal soap.
Wait a day or two after applying and re check the hill.
How to get rid of ants in my flowers. Buy some ant bait and place it along any trails you see leading away from the plant. Fill a bucket or bowl large enough to hold the flowers with water. For even better results add in a tablespoon of mild dish detergent to the water before using.
Boiling water is a great way to get rid of ant hills around plants. If you have honeydew you need to wash the plants or ants will keep returning. If you cut the flowers in bud refrigerate them immediately.
Cut the flowers when they have fully opened as ants are attracted to the sucrose that collects on buds. Odds are the ants have a larger nest outside. You need to remove the honeydew to prevent mold.
First get rid of the insects providing the ants with honeydew to eat. Dunk the flowers inside the bucket and shake them gently back and forth to loosen the ants from the flowers and help them float off. Use an insecticidal soap or pyrethrum spray.
The oil in the soap will help increase the effectiveness of the solution. They ll carry this bait back to the nest thinking it s food and will kill the whole colony. Within 24 hours the ants will become very sluggish making it easy to wipe them off the buds.