The star magnolia (Magnolia stellata) is a deciduous flowering tree that normally reaches a height of 15 to 20 feet at maturity, with a slightly smaller spread. The star shape of its white flowers gives it both its common name and scientific name. It blooms in March or April, making it one of the true harbingers of spring. Fuzzy, pussy-willow-like buds precede the spring display of mildly fragrant flowers.
Star magnolia has a rounded habit and can be grown into a tree form with pruning. Otherwise, it is likely to grow as a shrub, which can be shaped into an oval or a round form. Some varieties are particularly suited to growing as shrubs.
Planting Zones, Sun, and Soil Requirements
Indigenous to Japan, star magnolia trees can grow in planting zones 4 through 8. Select a site that is well-drained, has acidic soil, and is located in full sun to partial shade. It flowers best in full sun. Plant in a loamy soil enriched with humus.
Uses in Landscaping
Star magnolia are attractive enough to use as specimen trees for the spring, when in bloom. As relatively small trees, they are more likely to be seen in foundation plantings or near patios than their larger counterparts.
These Japanese stalwarts often blossom a bit earlier (March and April) than saucer magnolias. Their precociousness after a long, hard winter is most appreciated by gardeners who desperately crave spring flowers. To this end, planting your star magnolia where it can be seen from indoors, or in an outdoor location that you pass by frequently, makes the most of the early bloom.
Growing Magnolia Shrubs
Although usually classified as a tree, Japanese magnolias often exhibit a tendency to grow as multi-stemmed shrubs or bushes. If you wish to avoid this look, prune away any suckers so as to train your specimen to assume a tree form. On the other hand, if you prefer a shrub form, the 'Jane' cultivar is an excellent choice. It can be pruned lightly for neatness in its first two years but should not be pruned after that.
Pruning and Care Tips
The plant blooms on old wood (last year's growth), so prune it more or less immediately after blossoming to avoid losing next year's flowers. People don't generally prune magnolias much (although M. stellata is sometimes a bit more tolerant of pruning than other members of its genus). If desired, you can prune away the lower growth as it emerges on an established star magnolia tree, while letting the rounded, spreading crown become dense.
On the one hand, you don't want strong March winds whipping around the flowers too much, because that will cause them to drop their petals prematurely. But on the other hand, planting them in a sheltered spot with a southern exposure can be a bigger mistake, because if the buds open up too early, they can be damaged by frost. Find a balance that's right for your area.
New growers are sometimes alarmed by the "funny growths" that appear on star magnolia trees in the latter part of the growing season. No need to worry, though: those odd lumps are just the pods in which star magnolia tree seeds are contained.