Lily trees, or Orienpet lilies, are the product of crosses between plants in the Oriental and Trumpet divisions of the genus Lilium. These are true lilies and, like all members of that group, survive cold winters as a bulb underground. The stems and leaves die in fall, and new growth sprouts in spring. It's always advisable to cut lily stems down to about 6 inches after they die.
About Lily Trees
"Lily tree" is a common name for some types of magnolias, true trees with branches and trunks, but it's also a term trademarked by Gurney's Seed and Nursery for the group of Oriental x Trumpet or O.T. hybrids, often called Orienpet lilies. Oriental lilies have huge, fragrant flowers but are difficult to grow in hot summer areas; they prefer cool summers and a somewhat acidic soil. Trumpet lilies are easier but often need staking. Hybrids between these two types combine the best of both, being vigorous, strong and more tolerant of both hot and cold weather than Oriental lilies.
A soil with excellent drainage and added organic matter is the first priority in growing all lilies. Give them full sun without reflected heat from a wall and mulch the roots or allow neighbouring plants to cover them with their foliage. Water whenever the soil becomes dry to a depth of an inch or so. Fertilise with a balanced mix such as 10-10-10 as the lilies sprout in the spring. Fall cleanup should include removing all leaves that may have dropped on the ground as well as cutting back the stems. Dispose of these in the garbage rather than the compost to avoid disease problems.
Planting and Transplanting
All lily bulbs, including lily trees, can be planted in either fall or spring, although a fall planting gives the bulbs longer to get established. Mulch with straw or dried leaves to protect them over the winter. Add organic matter and some bulb food or bone meal to your lily bed and work at least a foot into the soil. Plant the bulbs with 4 to 6 inches of soil over the top. Fall is also the best time to dig up clumps, divide the clusters of bulbs and replant, though this should only be done if the clump seems to be losing vigour. Lilies dislike being disturbed.
Varieties of Lily Trees
White Orienpet lilies include "Opulent," "Luminaries" and "Carte Blanche." Yellow varieties include "Conca d'Or," "Serrano" and the red-brushed "Secret Message." You'll also find deep pink, melon, cream, orange, raspberry, peach and rose-red varieties. Many, however, tend to fade in heat and strong sunlight.