Asiatic lilies are one of the most popular types of lilies in the United States. They beautify the garden during the early- to mid-spring with large--sometimes freckled--flowers in a multitude of colors. They are hardy perennials that grow in USDA plant hardiness zones 3 to 8, and reach anywhere between 2 to 5 feet tall. Fortunately, Asiatic lilies must have just a few needs met in the fall in order to grow, bloom and thrive again the next growing season.
Remove all but 2 inches of the wilting foliage after the first killing frost in the fall. Use pruning shears for an easy job. By leaving the foliage on as long as possible, your Asiatic lilies have had the most time to soak in the sun's energy to store in their bulbs for next year's plants.
Divide Asiatic lilies in the fall (after you cut off the foliage) if your garden is overcrowded or they bloomed less than usual (a sign of overcrowding). This typically needs to be done every three to four years. Dig them up with a garden fork (they're planted about 6 to 8 inches deep) and split apart the small bulbs attached to the parent bulbs with your hands. Replant the bulbs as soon as possible. Smaller bulbs should be planted near the rear of the garden, since they may not bloom the first year.
Lay mulch, such as leaf mold or wood chips, around your Asiatic lilies, especially in zones 3 to 7, where the ground may freeze, thaw and refreeze throughout the winter. Lay anywhere 3 to 6 inches of mulch. The colder the zone, the more mulch you need, especially if your climate does not receive a reliable winter snow cover (which actually insulates the ground and keeps it warm).