[header] How to keep ants off peonies [title] Apply an insecticide to the peonies. [step] One of the most effective ways to control an ant problem on peonies is to spray the plants with an insecticide. Before choosing a product to spray, make sure that the manufacturer specifically states that the product is effective against ants. 
Apply the insecticide according to the manufacturer's directions. [substeps] This method will not generally be acceptable if you are committed to gardening organically or do not want to harm the beneficial insects that aid the plants in pollination.