Lilies, of the genus Lilium, are a group of plants that grow large, colorful blooms and spear-shaped leaves. These plants are relatively hardy, and they're popular in home gardens for their wide range of colors and blooming times. All lilies grow from bulbs, which divide naturally as time goes on. To propagate new lilies and keep established plants going, gardeners separate these bulbs at specific times every year.
Lilies grow and bloom through the summer, though different types have different blooming schedules. Most lily gardens bloom from June through September and should be left alone at this time; the plants are expanding and working to grow.
Although gardeners divide lilies to propagate new plants, this division is also important for the health of the established plant. If the plant is growing spindly or crowded, or is blooming less than it did in the past, it may need division. Watch the plants during the growing season to monitor their progress. Many gardeners divide their lilies every three years to keep them healthy.
Mid-fall is the best time for dividing and moving lily bulbs. At this time, the plants are entering their dormancy and will handle the stress of division without taking too much damage.
Dig up and divide lilies when they still have some foliage. This makes it easier to locate the bulbs and their separations, since each division will have its own set of roots and shoots.
To divide lilies, dig up the bulbs of the established plant and find the natural divisions in the bulbs. Pull, twist or cut the bulbs apart at these divisions, leaving both roots and foliage intact on each piece. Move the new pieces to new locations and replant the parent lily.
Choose the right location for the new lily bulbs. Lilies require full sun, good drainage and quick-draining, nutritious soil. Plant the new bulbs in an area where they'll have plenty of space to grow and expand.