Osmanthus decorus Turkey olive, Caucasian osmanthus

Turkey olive comes from Asia Minor where it was first found in the region of Lazistan (Turkey and partly Georgia) at the Black Sea coast. It is a warm and humid subtropical climate without winter frosts, but with enough precipitation during autumn and winter, i.e., large-leaved evergreen trees thrive there as they do not need to be waterwise. The plant was discovered and described for the first time by the French botanist Édouard Louis François Balansa (1821-1891), who was famous for his research and collection of new plant species in North Africa, the Middle East and South America.

If you have already come across some osmanthus species and you get to see Osmanthus decorus for the first time in your life, you probably won't associate this species with the others. Rather than that you might think "hmm, what a weird oleander...". The truth is that even earlier botanists had a problem with it and for many years it was classified as phillyrea – Phillyrea decora or even Phillyrea laurifolia (laurel-leaved). It was not until modern science confirmed a greater genetic affinity with osmanthus than with phillyrea. Aren’t we lucky to have modern science that can explain and categorize everything under the sun? Just fancy going to bed without knowing for sure if a plant belongs here or there! Oh no, it can cause so many sleepless nights… And, in case someone reads this in 100 years from now, when science will have brought much progress and findings and everything will be completely different, don't get mad at me, please.

Its evergreen leaves are entire - spine-less, narrowly elliptical which means elongated and pointed at both ends. They are rather large for an osmanthus – they can be up to 13 cm long and 2-3 cm wide. The upper side is slightly glossy, dark green in partial shade and with light olive-green hues in full sun and reveals quite noticeable veining. The underside is light green. Unlike other species, the leather leaves have perfectly smooth margins without prickly spines and are not so stiff. The short petioles are dark red, the young twigs are olive yellow-green, and the older branches and trunk are smooth and gray.

Like other osmanthus, it blooms profusely, but in this case in spring (like phillyrea – hence the historical chaos). The flowers are white, tiny, densely clustered in the axils of the leaves like fluffy pom-poms and sweetly fruity scented. The strength of their fragrance is not as intoxicating as in the case of autumn-flowering osmanthus.

It forms a medium-sized evergreen shrub with upright branches, spreading with age, thickening into an almost impenetrable bush. It can be pruned in any way from spring to early summer. As it has large leaves, using a hedge trimmer, you will cut the leaves in half which will be visible and ugly, so do this only in spring because it will soon be covered by new growths. Otherwise, it is better to prune it using hand shears and cutting only the branches.

It might sound like degradation, but in its native habitat it is most often used as a durable and evergreen filler shrub. However, plant lovers and collectors of evergreen specialties will definitely make this osmanthus a specimen shrub or combine it with other evergreen shrubs of a different texture for the best contrast. It also looks good integrated into green screens and hedges, where I personally enjoy mixing it with other hardy evergreen shrubs such as Phillyrea, Quercus ilex, Arbutus, Ilex crenata, Choisya, Elaeagnus x ebbngei, Prunus lusitanica and Photinia.

Grow osmanthus in moist but well-drained, humus rich, preferably acidic soil. Provide plenty of mulch for winter to protect the roots from quick freezing. It loves full sun but in colder regions find it a location sheltered from late winter and early spring sunlight but with plenty of light during the growing season. Use only plants with mature wood in zone 7 and transplant it no later than late summer in order to avoid frost damage after the first winter. So far we have tested its hardiness down to -20°C without significant damage (USDA zone 6b) and further trials continue. Unlike autumn-flowering species Turkey olive requires more winter moisture so water it once a month during dry winters unless the ground is frozen. Young plants with immature wood must overwinter indoors until they have hardened up. Sweet olive does not suffer from diseases, but vine weevil can be a problem.

Last update 10-11-2024