Styrax

These evergreen trees or shrubs can be used to plug the "June gap", says Miranda Kimberley

Image: Floramedia
Image: Floramedia

Gardeners often search for plants to fill that strange gap between late spring and summer, when there is a lack of flowering plants. Styrax is a deciduous or evergreen small tree or large shrub which can be used to plug this "June gap", their main feature being pure white flowers that hang elegantly from the branches.

There are around 120 species of Styrax, in warm temperate and tropical regions of the Northern Hemisphere. The majority are in eastern and south-eastern Asia, with many species in China and Japan. The best known here is Styrax japonica, usually referred to as the Snowbell tree. It is arguably the finest of the Styrax trees, with a graceful habit and a tough nature. Its bell-shaped flowers are pure white with yellow stamens, borne in profusion along the branches.

Other Styrax of note include the Big-Leaved Styrax, S. obassia, which has large, handsome leaves with a soft, velvety down on their underside. It becomes a beautiful large shrub or small, round-headed tree and its fragrant flowers are borne in long racemes. Another species with an Award of Garden Merit is S. hemsleyanus, a Chinese form introduced in 1900 by Ernest Wilson. It also features attractive foliage – its leaves are similar in appearance to S. obassia, but are not downy, and they are a delicate pale green colour.

In terms of hardiness, the Styrax species vary a little, with the trees coping with low temperatures between -5 and -15°C. Styrax japonica and S. obassia are the hardiest, surviving down to -15°C, but there are others at the other end of the scale such as S. benzoin, which is frost tender. If they are given the shelter of a south-facing wall, that is the ideal situation. They must be protected from cold, drying winds. Plant Styrax in moist, loamy, lime-free soil in sun or partial shade. They are best planted among other shrubs and trees where they will receive some protection. However, be aware that their roots do not like competition.

In terms of how to use them, they make excellent specimen trees or shrubs. They are slow growers, so especially suit the smaller garden. But they also look good planted in groups. Viewing them from below is recommended, where their dainty flowers can be fully appreciated, so planting them into a terrace garden works very well. They also look particularly good when branching out over ponds, streams or garden paths. Other attractive features include good autumn colour, displayed by S. hemsleyanum and S. obassia, which also has attractive bark as does S. japonica.

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What the specialists say

Bleddyn Wynn-Jones, co-owner, Crûg Farm Plants, Gwynedd

"In our experience, it is difficult to beat the readily available Styrax japonica. We have made several seed collections in the wild of this species and grown their progeny in our trial fields where they are exposed to some severe conditions due to the lack of shelter. They all fly through without any ill-effects, flowering profusely every year.

"We have also done the same with Styrax formosanus, which for us have a more upright habit. They require a bit more shelter from cold winds, which is why we grow them in a more sheltered field with high hedges, where again they do flower well.

"We have also introduced S. tonkinensis or S. suberifolius, which again show great promise, but require a bit of age before they start to flower. As for hardiness, a single plant in our garden showed no ill-effects during the cold winter of 2010/11.

"I would advocate planting a bare rooted or open ground-grown plant, as they seem to grow far better under these conditions. And being much larger plants, they give the gardener far more value for money, especially if they can collect them from the nurseries themselves.

Steve Dance, office manager, Burncoose Nurseries, Cornwall

"Styrax is a beautiful tree that fills a gap between the spring flowering period and the summer. They can become either large shrub or small tree with a graceful habit, that suits a woodland garden. They are also attractive to bees.

"I think that the best species is Styrax japonica. It has pendulous, bell-like flowers in profusion. This one is a trouble-free species. Its best grown in partial shade, in humus rich neutral to acid soils. I would avoid planting them where they can be affected by cold, dry east winds."

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In practice

Ben Wighton, assistant head gardener, Lincoln’s Inn, London

"Styrax is not a tree often seen in gardens in the UK. I think this is partly because its not widely stocked by nurseries and its not on the radar of many designers and landscapers. They are perhaps less inclined to experiment with trees new to them while we are having erratic winters, with extremes of cold and wet.

"But it’s a lovely specimen tree, which is best situated in a position near an area you might sit, like a patio, where its gorgeous, hanging white flowers can be admired. It has a nice smooth grey bark that is also a nice feature. It works well planted in a group – perhaps in a woodland or woodland style garden, underplanted with delicate bulbs or shade loving plants."

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Species and varieties

S. americanus is a shrub or small tree with a spreading, open crown which produces masses of dainty, white, bell-shaped flowers that hang from the branches in early summer. The flowers have narrower petals than the more commonly seen Styrax japonica and small, dark green, oval leaves. Reasonably hardy, but requires shelter from cold winter winds. Height 3m and spread 2.5m.

S. confusus is a rare small tree with long pointed leaves. It produces clusters of small, white, perfumed bell-shaped flowers, with more open petals than S. japonicus. It can withstand temperatures down to -15°C. Plant in full sun or partial shade in a sheltered position. Height 6m and spread 3m.

S. dasyanthus is a slightly tender species whose flowers hang in slender terminal racemes. Plant in full sun or partial shade. Can withstand temperatures down
to -5°C.

S. hemsleyanus AGM is a medium sized tree with an open habit. It produces long racemes of wide, pure white flowers in mid-summer. The leaves are pale green and much larger then those of a Styrax japonica, which means its foliage is a feature in itself. Reasonably hardy, withstanding temperatures down to -15°C. Shelter from cold winter winds. Height 8m and spread 5m.

S. japonicus is an attractive, spreading tree that produces masses of pendulous bell-shaped white flowers in the summer. It features finely-pointed, ovate, mid- to dark green leaves, which turn yellow or red in autumn. It can withstand temperatures down to -15°C. Flowers reliably when young. Height 10m and spread 8m.

S. japonicus (Benibana Group) ‘Pink Chimes’ AGM is a graceful, spreading tree with a profusion of delicate pink, bell-shaped flowers. It produces elliptic-oblong, minutely-toothed, glossy, mid- to dark green leaves which turn yellow or red in autumn. Reasonably hardy. Height 10m and spread 8m.

S. japonicus ‘Fargesii’ AGM has a more tree-like form than the straight species, with larger leaves. It produces white, bell-shaped flowers with yellow stamens (larger than the type). It  leaves are glossy, mid- to dark green and turn red or yellow in autumn. Height 10m and spread 8m.

S. obassia is also known as the Big-leaf Styrax because of its large ovate leaves, which are glossy, deep green above and downy beneath. They turn yellow in the autumn. It has fragrant, white bell-shaped flowers with a golden yellow centre. Can take up to six years before flowers well. Height 12m and spread 7m. 

S. officinalis or the Mediterranean Storax needs a warm sheltered site. It produces oval, dark green leaves, which are grey-white beneath and short drooping clusters of large fragrant flowers. Probably less hardy than other Styrax – can cope with temperatures between -5 and -15°C. Height 6m and spread 5m.

S. wuyuanensis is a rare species with clusters of long white flowers. Plant can withstand temperatures down to -15°C. Height 1.5-3m.


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