Magnolias (Magnolia spp.) are technically any of the flowering shrubs and trees that belong to the genus "magnolia," which includes around 80 individual species, native to North America and Southeast Asia. Many gardeners and landscapers know the tree best for its large, showy blossoms, which suit it well to cultivation as an ornamental specimen tree. Historically, some species of the tree have been used for timber or for medicinal preparations.
Most varieties of magnolia grow best in full to partial sun. Generally, they prefer soil that is moist but well drained, fairly intolerant of either wet feet or drought. One exception is the Southern Magnolia or Bull Bay Magnolia (Magnolia grandiflora), which is well adapted to drought conditions once its root system has developed. For ideal growth, look for a sheltered site, where the tree will not endure harsh winds, which can be detrimental to the tree's relatively delicate branches and leaves, as well as its blossoms. Preferred climate conditions vary among cultivars, though some cold-hardy magnolia varieties may thrive in zone 3, while other varieties may grow in zones 8 or even 9.
Avoid transplanting magnolia trees, as they have delicate, ropy root systems. If absolutely necessary, transplant before the tree's trunk has reached a diameter of 4 inches. Plant an evergreen magnolia in the early spring and a deciduous magnolia in the fall. You can propagate a magnolia by seed or from cuttings, grafting or layering. Propagation by cuttings is most effective when taken from juvenile trees.
Magnolias are relatively resistant to most pests and diseases, compared with other ornamental tree species. However, you should monitor for any signs of soft or armoured scale insects. In addition, the magnolia root borer (Euzophera magnolialis) occasionally targets the species. Nematodes can also pose problems, attacking the tree's roots. In some cases, larger wildlife targets the tree's seeds and flowers. On the other hand, usually beetles pollinate the magnolia, not bees or butterflies; avoid removing apparent pests you cannot identify, as they may be helpful pollinators. Watch for any signs of disease, such as stem canker, powdery mildew, rot or verticillium wilt.
You can select from many varieties of magnolia, each suited to slightly different growing conditions and presenting a slightly different appearance. For warm climates, consider the cucumber magnolia (Magnolia acuminata) or the Ashe magnolia (Magnolia macrophylla var. ashei). The umbrella magnolia (Magnolia tripetala) is small to medium-sized, ideal for smaller yards. Several hybrid cultivars, derived from M. stellata and M. x soulangiana, produce early blossoms; they are known collectively as "The Girls," because of their female names: Ann, Betty, Judy, Randy, Ricki, Susan, Jane and Pinkie.