Lilies are a tall, large, star-shaped bulb-blooming flower that provide summer fragrance and color that's difficult to top. Asiatic lilies, which typically bloom in early summer, grow to about four feet high in bright, hot colors with stems covered in short, lance-shaped leaves. Oriental lilies are late summer flowers, often sweetly fragranced, reaching heights of six feet and blooming in speckled, streaked, or spotted color combinations. Lily bulbs are imbricate, or plated, bulbs that will create tiny baby bulbs as they mature. Dividing these bulbs to gain more beautiful plants is well worth the minor effort it takes to accomplish the task.
Divide lily bulbs every three years during the fall. When the stems appear crowded and blooms are not as large or healthy looking as when first planted, division is necessary.
Prepare the new bedding site by incorporating 3 to 4 inches of organic material, such as compost, up to 8 inches deep to improve drainage.
Dig a hole around the bulb site carefully, to avoid disturbing the small bulblets forming on the mother bulb.
Raise the clump and brush away the soil. You will notice small, baby bulbs forming either above or below the mother bulb.
Gently pull the bulblets away from the mother bulb, leaving the roots intact to each small clump of new bulbs. Keep in mind that tiny bulbs may take up to a year to develop into flowering bulbs, so they may not yield flowers the first growing season after planting.
Re-plant the small bulblets 2 to 4 inches deep, and larger, more mature bulbs at 6 inches deep. The University of Minnesota experts suggest allowing 8 to 12 inches between each bulb, and 3 to 5 feet between clumps of bulbs.