Many perennials should be staked to prevent them from bending or falling over during wind and rain. When staking is done correctly, the plants grow to cover the stakes. Remove old flowers to encourage rebloom on perennials. Many perennials should be cut back to ground level after bloom is finished to encourage new leaf growth from the base. Remove dead foliage and stems in the fall, and mulch to protect crowns and roots from alternating mild and freezing weather.
Most perennials eventually become overcrowded and require division.
Information on division is available in Dividing Perennials, HGIC 1150. Many perennials are also easily propagated in this way. Other methods of propagating perennials include stem cuttings, root cuttings and seed. Selection of resistant species and cultivars, proper site selection, and good cultural practices will prevent many disease problems. Many perennials are available in several cultivars with different color, height or other attributes.