Star Jasmine

Family

Apocynaceae

Habit

Climber

Height

6 m

Spread

6 m

Growth

very slow

Lifespan

20 years

First yield

after 3 years

Hardiness

zone 9–10

Shade tolerance

light shade

Soil

Sand, Silt, Loam

Soil moisture

semi-dry – very wet

pH

5.3 – 8.6

Other uses: The real value of star jasmine lies in the combination of evergreen foliage and scent. From June to August the white, five-pointed star-shaped flowers give off an intense, jasmine-like fragrance that grows markedly stronger at dusk and through the night and carries several metres; accordingly the plant is deliberately sited beside seating, entrances and under bedroom windows. The flowers are used in perfumery and for potpourri. Horticulturally it is of interest as one of the few evergreen climbers for winter-mild positions: on a trellis, pergola or tensioned wires it forms dense, year-round screening, while without support it spreads flat as a dense groundcover. The milky sap makes it uninteresting to deer and rabbits.

Site: In central Europe star jasmine is only conditionally hardy. It takes about minus twelve to minus fifteen degrees briefly, so permanent planting out succeeds only in winter-mild wine-growing districts and sheltered urban climates; everywhere else it belongs in a container. It wants a sunny to half-shaded and above all wind-sheltered spot, ideally against a heat-storing south wall, in humus-rich, free-draining, rather acidic soil without waterlogging. As a twiner it winds around supports and needs a framework, wire or tensioned cables from the outset; it will not cling to a smooth wall. Its scent makes proximity to seating and windows worthwhile, while its irritant milky sap argues against placing it where children handle fresh cut surfaces. Care: Keep evenly slightly moist from March to September and feed every ten to fourteen days with a complete container-plant fertiliser; waterlogging in the pot or saucer is the commonest mistake and leads to root rot. Repot container plants into fresh compost every two years in spring. Overwinter bright and cool at around five to ten degrees, for instance in a light garden house or under cover against the house wall, bringing it in during December and out again from March. Plants in the ground need thick winter protection over the root zone and fleece on the shoots. Prune after flowering in late summer, which encourages branching and next year's flower set. Wear gloves when pruning.

Star jasmine is propagated from cuttings. Most reliable are semi-ripe tip cuttings about ten centimetres long, taken from non-flowering shoots between June and August. The cut surfaces bleed milky sap and should be rinsed briefly in lukewarm water or left to dry off, or the dried sap blocks the vascular tissue. Strip the lower leaves, insert the cutting in free-draining propagation compost and keep it under film or a cover at around twenty to twenty-five degrees in high humidity; roots appear after four to eight weeks. Rooting powder raises the strike rate considerably. Layering works just as well: nick a low shoot, bury and weight it, and it can be severed after a season. Seed plays no part, as the plant sets almost none in central Europe.

Star jasmine is an East Asian neophyte with no specialised associated fauna in central Europe. Its flowers are long and narrowly tubular and release their nectar deep down, so short-tongued insects cannot reach it; the beneficiaries are mainly long-tongued species such as butterflies, hummingbird hawk-moths and bumblebees, and the fact that the scent intensifies at night points to moths as the original pollinators. For honeybees it is of little value. Its real contribution lies elsewhere: as an evergreen, densely branched climber it offers cover and nesting opportunities on walls and pergolas all year, particularly in winter when broadleaved plants stand bare, and wren, robin and blackbird use such structures regularly. The milky sap reliably protects it from browsing by deer and rabbits.

Notable: despite the name not a jasmine but a dogbane relative - it shares only the scent with Jasminum; the fragrance intensifies markedly at dusk+night and carries several metres; one of very few evergreen climbers for winter-mild positions; without a support it simply spreads on as groundcover; does not flower until it has gained height.

East Asia: China, Japan, Korea, Vietnam. Star jasmine comes from the subtropical to warm-temperate forests of East and Southeast Asia, centred on central and southern China, the main Japanese islands and the Korean peninsula; southwards its range reaches Vietnam. Related species of the genus also occupy the Himalaya, Tibet, Indochina, Sumatra, Java and Borneo. It has long been a garden plant in East Asia and, through European and American horticulture, has spread worldwide in winter-mild climates, especially around the Mediterranean and in the southern United States. In central Europe it exists only in cultivation and does not naturalise.

In its homeland star jasmine grows as a woody liana in open, warm forest and along woodland edges, climbing trees and scrambling over rock to elevations of around 1100 metres. Its habitat is shaped by mild, moist winters and warm, rainy summers: a climate without long frost periods and without pronounced summer drought. It grows there in the half-shade of the canopy and only flowers once it has worked its way up into the lighter storeys, a trait that carries over into cultivation, where young plants invest first in shoot length. The soil is typically humus-rich, free-draining and slightly acidic.