Sweet Olive, an Evergreen Shrub with Fragrant Flowers
Native to Asia, the sweet olive is a large shrub or small tree that is capable of growing 20 to 30 feet tall in mild coastal areas. In regions farther north, damage from low temperatures limits its growth, so it is more frequently seen at 10 to 15 feet tall. Nevertheless, those who can grow sweet olive are sure to include it in their gardens, for it can fill a large garden space with its fragrance.
Even when tucked into back nooks and crannies, its impact can be significant. The fragrance, which is produced by visually insignificant tiny white flowers that bloom in clusters along the stems, can be smelled from several hundred feet away. One might never notice sweet olive except for its enticing fragrance, for it is a nondescript, green, somewhat rangy shrub. Dark green, glossy foliage is borne alternately along the stems and it is attractive enough. However, it is likely not a first choice of the gardener who must have perfectly shaped plants.
Sweet olive blooms throughout the season during mild winters. Usually, though, it shuts down for very cold weather and struts its stuff during late fall to early winter and again in early spring. Very long lived and infrequently bothered by pests and diseases, it can be found in many old gardens of the South.
Culture, Propagation, and Varieties
For best performance, plant the sweet olive in fertile, moist but well-drained, slightly acid soil in full sun to partial shade. Fertilize lightly in spring when growth begins with a slow-release, complete fertilizer if the leaves seem a bit pale. Cuttings taken from half-ripened wood root well when placed in moist growing medium. Pruning is not usually necessary, but old specimens can be limbed up and grown as small evergreen trees.
The Native Cousin
The South is blessed with a native sweet olive that is called devilwood or wild olive. Osmanthus americanus can be found from southeastern Louisiana eastward to Florida and as far north as Virginia. The flowers are not at all showy, and they are not as fragrant as its Asian cousin. Dark blue berries that reveal its inclusion in the Oleaceae (olive family) ripen in September and are a food source for many birds and small animals.
Devilwood deserves greater use as an ornamental. Slow growing, upright form, and smooth, silvery gray bark are all attractive, but people who live along the coast particularly appreciate its wind resistance. The hurricanes that sweep through from time to time have little effect on the tough devilwood. Since it is the most cold tolerant Osmanthus, it can be grown farther north than other species.
Evidently someone once tried to use the wood for one purpose or another, and it turned out to be a devil to work with because the wood is extremely hard and tough. This might suggest to those who choose to plant a devilwood in their landscape that it should be in a place where pruning will not be necessary. This should not be a concern, however, for the natural shape is attractive and if properly placed, no pruning will be needed.
Other Osmanthus Species
Osmanthus heterophyllus (holly tea olive, false holly, or holly osmanthus; Zones 7 - 9) is used in borders, hedges and barrier plantings where its extremely spiny leaves can be utilized. Several cultivars are available in various sizes and leaf characteristics that may be better choices for many landscapes.
Osmanthus ×fortunei (Fortune's osmanthus, Zones 7 - 9) is a hybrid of O. heterophyllus and O. fragrans and has characteristics of both parents. Juvenile leaves are spine-tipped, but the adult leaves have no marginal spines. Fragrant flowers bloom in late fall, and it can grow into a large oval to rounded shrub 15 to 20 feet high and wide.
Osmanthus ×burkwoodii (Burkwood osmanthus, Zones 6 - 8) is a dense, rounded shrub that grows 6 to 10 feet tall and wide. This evergreen shrub bears fragrant flowers characteristic of the genus.
Osmanthus delavayi (Delavay osmanthus, Delavay tea olive; Zones 7 - 9) is native to western China and grows 6 to 8 feet tall and a bit wider. It has twiggy growth and graceful arching branches that are well covered with small, glossy, dark green, ovate leaves. Fragrant flowers bloom in spring, and it is more widely grown in the western states since it prefers alkaline soil.
Osmanthus serrulatus (wild sweet-scented Chinese osmanthus, Zones 7 - 9) grows 6 to 12 feet tall, bears fragrant flowers, and is a slow-growing broadleaf evergreen shrub. Leaves are lustrous, leathery textured, and strongly serrate. On mature plants they may become entire and loose their toothed edges.
Osmanthus suavis (Himalayan osmanthus, Zones 7 - 10) is more upright than other Osmanthus species, and tends to be a bit leggier. In late winter to early spring, however, it is literally covered with clusters of white, fragrant flowers. Osmanthus decorus is another species that is evergreen and bears fragrant flowers. It seems to be less well-known than other species.Osmanthus yunnanensis (Yunnan osmanthus, Zones 8 - 10) grows up to about 33 feet tall, so it one of the largest of the genus. Ivory-white, mildly fragrant flowers are almost hidden from view by the large, olive-green, leathery leaves. Although rarely cultivated in the United States, Woodlanders Nursery lists it for sale on their site.
The author acknowledges and thanks the following people for allowing the use of their photographs in this article:
Patp - Osmanthus fortunei; Lilwren - Devilwood; Growin - Osmanthus yunnanensis, O. serrulatus, and O. decorus; bootandall - Osmanthus fortunei f. aurianticus