Osmanthus

Neat leaves, a tough constitution and fragrant flowers are a winning combination, says Miranda Kimberley.

O. heterophyllus 	‘Variegatus’ AGM - image: Floramedia
O. heterophyllus ‘Variegatus’ AGM - image: Floramedia

Evergreens that sit quietly at the back of a border are easy to dismiss. But when they are coupled with a heady fragrance they suddenly become more valuable and attractive. Osmanthus have a winning combination of neat, dark-green or variegated leaves, a tough constitution and flowers that can rival jasmine.

There are around 35 species of Osmanthus, all evergreen shrubs or small trees native to southern USA and Asia, with the majority of the garden-worthy species originating in Japan or China. They reside in the olive family, Oleaceae, with their leathery leaves that have spiny toothed margins.

Sometimes they are confused with hollies but the distinction is that Osmanthus have opposite pairs of leaves whereas hollies’ are alternate. They nearly always have fragrant flowers that are white, yellow or orange and tubular in shape, borne usually in spring or autumn.

The most commonly seen is probably O. × burkwoodii Award of Garden Merit (AGM), an adaptable large shrub with ovate, dark-green leaves and fragrant white spring flowers. It combines the beauty of one parent, the Chinese O. delavayi AGM, and the toughness of its other, the Turkish/Georgian O. decorus.

Another popular species is the autumn flowering O. heterophyllus, also known as the holly olive, with its spiky edged leaves. There are several interesting colour forms. The most used is ‘Goshiki’ AGM. The name means "five colours" in Japanese, referring to the shades of cream, pink, orange, yellow and white found on the leaves. ‘Purpureus’ is notable for its purply/dark-red juvenile growth. ‘Variegatus’ AGM has leaves with creamy-white margins.
O. delavayi AGM is a lovely plant in its own right, with small, neat, finely toothed leaves and
spring flowers that are more fragrant and a purer white than its offspring, O. × burkwoodii AGM.

The tough O. armatus has larger leaves with particularly spiky margins. It is another autumn flowerer.

They are not particularly fussy about where they are sited, doing well in most soils, and can be planted in sun or part shade. Most are hardy but there are a few such as O. fragrans that are slightly tender and should only be used in gardens with a warm microclimate. They do best treated to a moist, well-drained soil with plenty of organic matter incorporated.

Use them as shrubs in mixed borders, as a foil to perennials or bulbs, or as hedging or screening. Some of the slower-growing flashy varieties such as O. heterophyllus ‘Goshiki’ AGM even suit being topiarised into neat domes. While they will all generally form medium to large-sized handsome shrubs if minimally pruned, they do cope with being trimmed to shape or hard pruned. As long as it is done straight after flowering, there will be plenty of flowers again the following year.

What the specialists say

Nick Murphy, owner, Harley Nursery, Shropshire

"We only grow O. × burkwoodii, O. delavayi and O. heterophyllus ‘Goshiki’. My favourite is O. delavayi. I like the small, neat, dark-green toothed leaves. The first two provide nice spring blossom.

The latter variety, with its distinctive holly-like leaves, flowers in the autumn. All three have fragrant flowers.

"Osmanthus seem to be bombproof plants. We grow them in a pretty exposed site facing cold easterly winds and they cope well. When planting them, a woodland site is recommended. They prefer a moist, well-drained soil and you can add plenty of organic matter."

Nick Coslett, marketing manager, Palmstead Nurseries, Kent

"We grow quite a good range. The most popular variety by far is O. × burkwoodii. It’s a good classic evergreen, highly sought after by housing developers who are landscaping their projects. Because it has small leaves it can be clipped into a hedge and has nice spring flowers that are very fragrant.

"The other popular species is O. heterophyllus, known as the holly-leaved form. There’s a great variegated form, ‘Goshiki’, which will become a tall shrub in time but at first can be a compact shrub with a nice dome, making it appeal to builders, who put it in front of their show homes. There’s another lovely coloured variety, ‘Purpureus’, which unfortunately we don’t grow. I like its purply/dark-red new growth a lot.

"For us, O. delavayi varies in popularity and we grow small amounts of O. decorus. We tend to get O. fragrans, which is on the tender side, and the tougher O. armatus from Italy. O. fragrans is best suited to areas of warmer microclimates, such as London. Both of them are lesser known, larger leaved forms that can become large evergreens."

In practice

Sonya Huggins, assistant gardener, Lincoln’s Inn, London

"O. × burkwoodii is a great staple plant for gardens, providing structure in a mixed border. It’s a robust hybrid that provides a lovely fragrance in April and May and is a great foil to perennials and bulbs. It’s tough enough that it can cope with a clematis growing through it, which adds an element of surprise.

"Using a variegated form like O. heterophyllus ‘Goshiki’ is a great contrast to darker-green leaved plants, making it pop out of a border. But it can also be kept in a large container for a long time, because it is quite a slow grower, to brighten up a patio corner."

Species and varieties

O. armatus or the sweet olive is a dense, rounded, evergreen shrub that produces sweetly scented flowers in the autumn months. Its long oblong or lance-shaped leathery leaves are very distinct because of their spiny toothed margins. Tubular flowers are followed by violet-coloured fruits. Height: 2.5-5m. Spread: 4m.

O. decorus is a tough, slow-growing evergreen that becomes a large, rounded shrub. It has quite large, glossy, pointed, smooth edged, dark-green leaves and clusters of small fragrant white flowers in spring, followed by purple/black fruits. Height: 3m. Spread: 5m.

O. delavayi AGM (H5) is a slow-growing, medium-sized evergreen that becomes a relatively compact rounded shrub. It has small, rounded or ovate dark-green leaves with finely serrated edges. Masses of scented, white, jasmine-like flowers appear on arching branches in April and May. Height: 3-6m. Spread: 4m.

O. heterophyllus ‘Goshiki’ AGM (H5) is a slow-growing, compact, evergreen shrub that produces holly-like, coarsely spined leaves speckled with cream and other shades. Young growth can be tinged pink. Clusters of small, fragrant white flowers are borne in late summer or autumn. Height and spread: 1.5m.
O. heterophyllus ‘Gulftide’ is a dense, evergreen shrub with a rounded habit. Its dark-green foliage has neat spiky margins. White, fragrant flowers are produced in late summer to early autumn. These are often followed by blue/black berries in the winter. Height and spread: 3m.
O. heterophyllus ‘Variegatus’ AGM (H5) is a slow-growing, medium-sized, evergreen shrub featuring spiny, ovate leaves with creamy-white margins. Small, fragrant white flowers are sometimes followed by black fruits. Height and spread: 2.5m.

O. yunnanensis AGM is a large evergreen shrub or small rounded tree that has coarsely toothed, deep-green leaves and ivory-white flowers in late winter with a beautiful fragrance. Reasonably hardy, but requires shelter from cold winter winds. Height: 4m. Spread: 3m.

O. × burkwoodii AGM (H5) is a highly popular hybrid with glossy, dark-green, slightly serrate, ovate leaves and highly scented white flowers in April and May. These are occasionally followed by black fruits. Height and spread: 3m.

Thank you to Floramedia, which supplied the images for this article from its photo library
www.floramedia-picture-library.com


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