Oriental lilies, when crossed with trumpet lilies, result in 'orienpet lilies' which are vigorous, 8-foot tall lily trees. Orienpet lilies, or Lilium henryi --- Lilium speciosum var. rubrum, are grown from bulbs. These hybridised lily trees should not be confused with Liriodendron tulipifera. Liriodendron tulipifera translates to lily tree, but these relatives of the magnolia tree are more commonly known as tulip trees. They are grown from cuttings or seeds and not from bulbs.
The optimum time to plant bulbs is in the fall, after flowers have faded. Transplanting, or moving existing and established bulbs from one area of the garden to another, is also best done during the autumn season. Since dried-out bulbs die, transplant bulbs while they are still moist. Once in the ground lay 4- to 6-inches of loose compost over the bulbs. Mulch will keep the soil moist, allowing roots to develop prior to the first freeze.
Four to six weeks into the blooming season, usually mid-spring, is another good season in which to transplant lily tree bulbs. Dig up the root system and inspect for daughter bulbs. These bulblets are often attached to roots. Clip the bulblet from the root and dust the wound with horticultural sulphur to prevent fungal infections. When separated from the mother plant's root system, the daughter bulbs are transplanted to a different garden area to form trees and blooms of their own. Choose a spot with dappled light as lily trees will not thrive in shade or in full sun. Space the bulblets 4 inches apart and prepare to stake the growing trees.
Summer and Winter
Hardy, healthy potted lilies can be transplanted in summer--simply ensure they receive adequate water. Winter is the least optimum time to transplant any plant because the ground is often hard and frozen. Conditions such as this impede good root development.