Shear back plants by one-third after their first flush of bloom is past to neaten plants and encourage a second flush of flowers later in the summer. Keep plants vigorous by dividing every 3-4 years in spring or early fall. Give newly set out or divided plants regular watering until established. While not as enticing to cats as true catnip, felines may still try to roll on catmints. If there are cats around, it's a good idea to protect young plants for a while with a dome made out of chicken wire. An annual layer of compost in fall or spring should provide catmint with all the nutrients it needs.