There are numerous plants that have the word "lily" in their name, such as daylily, toad lily, and spider lily. However, these plants are not true lilies. The genus name for true lilies is "Lilium" and applies to the popular Easter lily and to such hybrids as Oriental and Asiatic lilies. There are hundreds of varieties of lilies hardy in zones 3 through 8 and appearing in a multitude of colors and sizes. Nevertheless, they all require similar conditions and care in order for them to grow and bloom successfully.
Apply a time-released balanced fertilizer at the first sign of new growth. A good time-released balanced fertilizer applied at the beginning of the growing season will give your lilies all the extra nutrients they might need for the entire season. Follow the instructions on the back of the package.
Top-dress your lilies with organic compost. As your lilies start their new growth for the season, amending the soil with some organic compost will add nutrients and promote good drainage. Just cover the area where your lilies are planted with about 1 to 2 inches of compost.
Cover the planting area with 2 to 3 inches of any type of organic mulch. A saying among lily growers is, "heads in the sun, feet in the shade." Lilies like the sun, but they also like their roots to remain cool. Applying a layer of organic mulch purchased from any garden center will help to accomplish this, plus it allows the soil to retain moisture.
Water for about 20 minutes once or twice per week during the growing season. Lilies, like most perennials, have deep roots, which require deep watering.
Gently remove any spent blooms. As the blooms fade and die, pull them from the stalk and discard.
Allow the stems and leaves to die back naturally. The stems and leaves will turn a yellowish color as they die. However, do not be too quick to cut them back. The bulbs take in nutrients through their stems and leaves for the next year's growth and blooms.
Cut your lilies back to the ground at the end of the season, after the stems and leaves have died completely. This is usually in the early to mid fall.
Mulch well. After you have cut back your lilies, apply 3 to 4 inches of mulch to provide them with protection through the winter months. The bulbs will do well left in the ground as long as they are covered with a good layer of mulch.
Divide in the early spring or early fall if they become too crowded and are not blooming as well as they once did. If you want to divide your lilies, dig up the bulb. You will see little bulbils, scales or offsets, depending upon the type of lily you have, around the main bulb. Gently remove these and replant all of the them and the main bulb immediately.