Stately Asiatic lilies (Lilium asiatic) stand tall in the flower bed so their slightly nodding blooms can draw the eye. These lilies grow in U.S. Department of Agriculture plant hardiness zones 3 through 10, so they provide a hardy perennial option for most climates. Like most lilies, the Asiatic varieties grow well with little care, but they do benefit from light pruning. Trimming keeps the plants looking attractive and removes old flowers before they can set seed, which allows the lily to focus its energy on storing nutrients for the following year.
Grasp the old flower head on the stem, just beneath the flower, after the flower wilts. Break off the flower, taking care not to damage any remaining flowers on the plant. Repeat for each flower after they wilt.
Trim out dead or badly damaged leaves as necessary throughout the growing season. Cut off the leaves where they join the main stem and dispose of them.
Prune back the entire lily plant to the ground after it yellows and dies back naturally in fall, taking care not to cut into the neck of the bulb. Remove the pruned foliage from the bed so it doesn't providing nesting materials for pests or disease organisms.