The massive, fragrant flowers of the herbaceous peony (Paeonia fruticosa) are lovely in the late-spring garden or floral bouquet. The trouble is that ants adore the blooms, too. The ants do not harm the plant, but are feasting upon a sugary coating on the flower buds and petals. Shaking or briefly dunking flower heads in water is one way to remove the ants, or harvesting cut stems of the peony while in a plump, bud form avoids any ant penetration. Disrupting the routes in which ants travel to peony plants and up stems is another way to deter ants, but it is labor intensive and usually not 100 percent effective.
Ant-Free Cut Flowers
Cut the peony stem when the flower bud is soft and plump with a pruners or sharp knife. According to cut-flower experts at Growing for Market, this is called "marshmallow stage" when the bud is plump and soft when pinched.
Shake or brush off any ants that are on the closed "marshmallow" peony bud and bring the stems indoors to place in a vase with fresh water. Cut peony stems and buds may be refrigerated up to two to three weeks to keep them fresh and in holding. Bring them into warm rooms with fresh water when you want them to open.
Submerge opened peony flowers in water to drown ants and wash them out of the many petals before bringing the blooms into the home. Alternatively. spray the flowers with a gentle-pressured stream of water from a nozzled garden hose to flush ants out to the ground.
Diminishing Ants on Outdoor Peonies
Prevent any peony stems or buds from touching nearby plants. Ants travel by any means to reach a food source. Having fewer pathways on other plants for the ants to walk onto the peony allows you to focus disrupting ants' access only on stem bases.
Disrupt the chemical path or scent trail left by ants as they travel to the peony plant. Scratching the ground or mulching can temporarily deter or slow the train of ants working to reach the peony.
Sprinkle freshly ground pepper, cloves or cinnamon at the base of the peony stems. Certain ant types will avoid walking through scented spices to reach a source of food. Focus the spice dusting at the base of stems where the ants begin their crawl up to the flowers.
Smearing a one to two inch band of petroleum jelly on the lower stems of peonies can also deter ants. Outdoor temperatures cannot be too warm, however, so the jelly does not liquify and allow the ants to easily trek over barren stem surfaces.