Destined always to be confused with true jasmine, Trachelospermum - or star jasmine - is a highly useful evergreen climber in its own right. It produces attractive star-shaped flowers, which on closer inspection appear more like perfect little windmills than jasmine flowers, although their sweet fragrance is similar.
The plants provide a dense cover of glossy green foliage that often takes on different colours in the winter. If placed by a sheltered, sunny wall they can be successfully grown in all but the coldest areas. Once established they can really romp away, reaching heights up to 10m and putting on vigorous growth every year that can be tidied back to a main framework.
As with many plants in the dogbane family, Apocynaceae, it has milky sap in the stems and leaves that bleeds out when cut. It is not considered poisonous but may cause a reaction with the skin and can cause staining on the ground beneath so care should be taken and hands washed after pruning.
There are 20 species of Trachelospermum, characterised by glossy, leathery leaves and white or pale-yellow flowers. They are native to eastern and south-eastern Asia, into Japan, Korea, southern China and Vietnam, with a single species in the south-east of the USA.
The two species widely grown in the UK are T. jasminoides Award of Garden Merit (AGM) and T. asiaticum AGM. The latter is the hardier of the two. If its woody framework is well ripened and the plant is in a sheltered spot in well-drained soil it will survive temperatures down to -15 degsC. It is neater and more compact in growth than the other species, with smaller leaves and flowers. The flowers are borne in July and August, distinguished by a yellow centre.
The less hardy T. jasminoides is best grown in a conservatory where temperatures fall much below -5 degsC. But in many areas it can establish well on a sunny wall and while slow-growing at first can grow up to 7m high or more. Its leaves are slightly narrower and longer than those of the other species and its flowers are very fragrant, starting pure white and becoming cream with age. They are produced from June to August.
There are several interesting varieties, but the straight species are still the most popular. T. asiaticum 'Ogon-nishiki' is a recent introduction that features foliage colour change throughout the year, with bright orange new growth giving way to glossy green leaves with yellow splashes that turn a range of green, orange and red in winter. T. jasminoides 'Star of Toscana' has flowers that graduate to the strongest shade of yellow as they mature.
Plants prefer a well-drained, moderately retentive soil in sun or light shade. Trachelospermum can be planted in containers, making them easy to bring into the conservatory over winter. They should be watered moderately during the growing season, but much less in winter.
The plants flower on short laterals on older wood. Pruning is advisable either after flowering or in early spring because plants can put on a lot of growth every year.
- What the specialists say
- Ed Cannon, owner, Langthorns Plantery, Essex
"Trachelospermum is a very useful genus of evergreen climbers for sunny or partly sunny sheltered walls. T. jasminoides 'Majus', 'Variegata' and 'Wilsonii' and T. asiaticum 'Golden Memories' flower reliably and prolifically from an early age. They are hardy, have healthy, glossy evergreen leaves and beautiful jasmine-scented flowers in summer - an obvious choice for a wall near an outside entertainment area.
"Other choice cultivars are 'Waterwheel', which has unusual lanceolate foliage with a distinct silvery midrib. It can be shy to flower, but is worth growing for the foliage alone. It gets beautiful autumn and spring tints to the foliage as the temperatures fluctuate. 'Golden Memories' has bright golden leaves.
"T. jasminoides 'Variegata' stands out for having the best winter colour. The variegated leaves turn wonderful hues of red as it gets colder.
"Soil preparation is the key to the success of growing Trachelospermum. They like humus-rich, deep but well-drained soil. They will grow on south, east or west-facing walls. Watch out for aphids, which love the fresh new foliage in spring. Feed with Sequestrine if leaves show signs of chlorosis."
- Kevin Hughes, owner, Kevin Hughes Plants, Wiltshire
"I grow 15 varieties of Trachelospermum, so you can see I like them. They are very containable, evergreen climbers. They clothe trunks or walls without becoming a menace. They have fabulously fragrant flowers and good foliage forms.
"My absolute favourite is T. asiaticum 'Pink Showers'
- the only one with pink flowers and, being a cultivar, is very hardy. Another great variety is T. asiaticum 'Ogon-nishiki', which has been given the trade name 'Summer Sunset'. It produces fiery red and orange foliage throughout the year. T. asiaticum 'Theta' is another stand-out variety - an improvement on 'Waterwheel' with even narrower foliage.
"All of ours came through the past winter, coping with an average of -9 degsC, and lows of -14.5 degsC. The only one that is easily killed is the big-leaved T. jasminoides 'Majus', which is best avoided unless you are in London or on the south coast.
"Plants can get scale or woolly aphid, especially when grown against a wall. Voles and rabbits can be a problem in rural areas because they like to nibble through the young stems. But Trachelospermum will come back from the roots quite well."
- Shelley Mosco, landscape architect and managing director, Green Graphite Landscape Design
"I've used T. jasminoides and T. asiaticum but because they are not fully hardy not as often as I would like. Our winter weather patterns have been so unpredictable lately.
"A recent project where T. jasminoides has been very successful, without much fuss, has been a sheltered, south-facing garden in central London, climbing a fourstorey building. Although it's a little more tender than T. asiaticum, it is more vigorous and a little more interesting because the leaves turn a bronzy red as the winter approaches. We have placed containerised plants either side of the back door and windows to enjoy its heavenly scent."
Species and varieties
- T. asiaticum AGM (H2) is a frost-hardy, evergreen climber that has darkgreen leaves and bears clusters of jasmine-scented, creamy-white, tubular flowers in July and August. It is initially slow-growing but soon covers a sunny wall or a structure in a conservatory. Copes down to around -10 degsC. Height: 6m. Spread: 3m.
- T. asiaticum 'Golden Memories' is an evergreen climber that has glossy golden leaves and fragrant white flowers in July and August. Height: 2m.
- T. asiaticum 'Ogon-nishiki' is a slow-growing, evergreen climber reaching up to 1.5m. Its foliage takes on many colours during the year. In the main it is glossy green, splashed with yellow, and the juvenile tips are bright orange. In winter, the leaves are green, orange and red. Fragrant white flowers that turn yellow with age are produced in July and August.
- T. asiaticum 'Theta' has distinctive grey-green foliage with a pale midrib and bears fragrant cream flowers in clusters.
- T. jasminoides AGM (H3-4) is a frost-hardy, evergreen climber with deep-green foliage that takes on a bronze flush in colder winters. It bears clusters of highly fragrant, pure-white flowers from June to August. Best grown against a warm, sunny wall in milder areas or in a greenhouse or conservatory in areas prone to severe frosts. Height: 9m. Spread: 3m.
- T. jasminoides 'Japonicum' is an evergreen climber that is taller and faster growing than the species. It bears glossy green leaves and fragrant white flowers in July and August.
- T. jasminoides 'Star of Toscana' is an elegant variety that bears fragrant and creamy flowers that mature to a soft shade of yellow throughout summer, against glossy dark-green foliage. Height: 9m. Spread: 3m.
- T. jasminoides 'Tricolor' produces soft pink and cream variegated young leaves that become dark-green then go redder in winter. Its creamy flowers are fragrant and borne between July and August. A slow-growing variety.
- T. jasminoides 'Variegatum' produces glossy green leaves with creamy-white margins and splashes. The foliage can take on red tinges in winter. Its fragrant white flowers are produced in July and August and turn to cream. Height: 2m.
- T. jasminoides 'Waterwheel' features narrow willow-like leaves with silver veins and small fragrant white flowers between July and August. Height: 7m.
- T. jasminoides 'Wilsonii' is a neat variety, with delicate bronze-flushed, dark-green foliage. Its fragrant, cream flowers are borne between June and August. Height: 3-5m.