Biology and characteristics

The Trachelospermum jasminoidesbelongs to the Apocynaceae family (subfamily Apocynoideae), like oleander or periwinkle. It is a woody evergreen climbing plant, native to East Asia (China, Korea, Japan).

Its scientific name comes from the Greek: trachelo-(neck) and -sperme(seed), referring to the shape of its flowers and its winged seeds.

Morphology

• Habit: climbing vine reaching 10 to 12 metres on a suitable support.
• Leaves: evergreen, oval to lanceolate, leathery, glossy dark green, 5 to 10 cm.
• Flowers: star-shaped, white to cream, 2 to 3 cm, very fragrant in the evening.
• Flowering: from May to July, sometimes extending into September.
• Fruits: elongated follicles containing winged seeds.
• Root system: aerial holdfasts allowing it to cling to supports.

Trachelospermum jasminoides is often confused with true jasmine (genus Jasminum), but these are two distinct botanical genera: the difference lies in the floral structure and the botanical family.

Origins and history

Star Jasmine grows naturally in open forests, woodland edges and humid mountainous areas of East Asia, up to 1,500 metres in altitude. It is notably present in southern and central China, in Korea and in Japan (where it is called Teika kazura).

Introduction to Europe

• 1844: first introduction by the Scottish botanist Robert Fortune during his trip to China.
• 19th century: cultivated in European botanical gardens (Kew Gardens, Jardin des Plantes in Paris).
• 20th century: popularised as an ornamental climbing plant for its fragrance and hardiness.
• Today: widely spread in Mediterranean, Atlantic and mild-climate continental gardens.

Traditional uses in Asia

In traditional Chinese medicine, Trachelospermum is used for its anti-inflammatory and antioxidant properties. The leaves were sometimes used in infusions against sore throats and digestive disorders.

Cultivation and planting

Exposure and climate

• Sun: sunny to partial shade, ideally 6 to 8 hours of direct sunlight per day.
• Hardiness: down to -15°C (USDA zones 7 to 10). Tolerates Mediterranean heat well.
• Protection: in cold climates, mulch the base in winter and protect young plants from frost.

Soil

• Type: well-drained, fresh to dry, slightly acidic to neutral (pH 6 to 7.5).
• Texture: loose, rich in organic matter.
• Planting: in spring or autumn, avoiding periods of frost and intense heat.
• Spacing: 1 to 1.5 metres between plants for a hedge.

Step-by-step planting guide

1. Choose a location sheltered from strong winds to protect the flowers.
2. Dig a hole twice as wide as the root ball.
3. Amend the soil with compost or planting compost.
4. Place the plant with the graft point (if grafted) above soil level.
5. Backfill and lightly firm down.
6. Water generously immediately after planting.
7. Mulch the base with bark or mineral mulch to retain moisture.

Avoid waterlogged soils, which encourage root rot.

Watering and fertilisation

Watering

• Young plants: regular watering the first year (1 to 2 times per week depending on heat) to encourage rooting.
• Established plants: drought-resistant, moderate watering during prolonged drought.
• Frequency: let the soil surface dry between waterings.
• Method: water at the base, avoid wetting the foliage to limit diseases.

Fertilisation

• Timing: a balanced fertiliser (10-10-10) in spring and after flowering.
• Type: fertiliser for climbing plants or flowering plants.
• Method: spread at the base, lightly incorporate into the soil, then water.
• Alternative: mulching with well-rotted compost.

Pruning and training

Pruning helps stimulate flowering by opening up the centre of the plant, controls the growth of the vine, removes dead or diseased wood and maintains an attractive shape suited to the support.

When to prune?

• Light pruning: after flowering (July-August), to remove spent flowers and shape the plant.
• Hard pruning: late winter (February-March), before the resumption of growth, to rejuvenate the plant.

How to prune?

• Use clean, sharp secateurs.
• Remove dead, diseased or poorly placed branches.
• Shorten overly long stems to balance the silhouette.
• Keep vigorous young shoots, which will bear the upcoming flowers.
• For a hedge: prune in a slightly conical shape to encourage sunlight penetration.

Tip: after hard pruning, apply a nitrogen-rich fertiliser to stimulate regrowth.

Propagation

Semi-ripe cuttings (the most common method)

1. Timing: June to August, on semi-ripe stems (neither too soft nor too woody).
2. Preparation: cut segments of 10 to 15 cm, just below a node.
3. Leaves: remove the lower ones, keep 2 to 3 leaves at the top.
4. Hormone: dip the base in rooting hormone powder (optional but recommended).
5. Substrate: a mix of compost and perlite or sand for good drainage.
6. Planting: pot up in small containers, under cover (greenhouse or cold frame) at 18-22°C.
7. Rooting: 4 to 8 weeks. Repot into individual pots as soon as roots appear.
8. Planting out: wait until the following spring to plant in the ground.

Success rate: 70 to 90% with this method.

Other methods

• Layering: aerial or by ground layering in autumn. Slow but reliable method.
• Seeding: possible but rarely used: long germination (2 to 3 months) and unreliable, plants not true to the parent.
• Grafting: rare, used to propagate specific varieties on resistant rootstocks.

Diseases and pests

Rust (Puccinia trachelospermi)

A common fungal disease characterised by orange-brown pustules on the leaves. Symptoms: rust-orange spots on the underside of leaves, deformation and premature drop, general weakening.

• Remove and burn affected leaves.
• Avoid excessive moisture on the foliage.
• Treat with Bordeaux mixture in spring and autumn.
• Open up the plant with a thinning prune to improve air circulation.

Powdery mildew

A white powdery fungus appearing on leaves and stems. Symptoms: white felting, yellowing and drying out of tissues.

• Treat with sulphur or a specific fungicide.
• Avoid excess nitrogen, which encourages the disease.
• Remove affected parts.

Scale insects

Sucking insects that attach themselves to stems and leaves. Symptoms: white or brown clusters on stems, sticky honeydew encouraging sooty mould, weakening.

• Clean with a cloth soaked in 70° alcohol or black soap.
• Apply horticultural oil or a systemic insecticide in spring.
• Introduce beneficial insects: ladybirds, lacewings.

Spider mites

Microscopic mites causing yellowing of the leaves. Symptoms: pale leaves with fine webs, yellowing and leaf drop.

• Increase ambient humidity by misting the foliage.
• Treat with a miticide or insecticidal soap.
• Avoid conditions of excessive dryness.

In case of severe infestation, isolate the plant to limit the spread to the rest of the garden.

Common problems and solutions

Yellow leaves

Usual cause: excess water (waterlogged soil) or iron deficiency (chlorosis). Solution: improve drainage and apply chelated iron.

Few or no flowers

Possible causes: lack of sun (less than 6 h/day), pruning too severe or at the wrong time, poor soil or phosphorus deficiency, age of the plant (young plants flower less).

Solutions: transplant to a sunnier spot, adapt pruning (avoid winter), fertilise with a fertiliser rich in phosphorus and potassium, be patient while the plant establishes a good root system.

Slow growth

Possible causes: soil too compact or poor, lack of water or fertiliser, roots smothered by overly thick mulch.

Solutions: aerate the soil and add compost, water regularly during the first year, lighten the mulch at the base.

Garden uses and companion planting

Main uses

• Ornamental climber for walls, pergolas, trellises and fences.
• Fragrant plant attracting pollinators (bees, butterflies) at the end of the day.
• Evergreen structure in winter.
• Ground cover when trained horizontally on a slope.
• Well suited to large container cultivation on a terrace or balcony.

Successful associations

• With clematis for a staggered flowering display.
• With climbing roses for a contrast of colours and textures.
• With honeysuckle (Lonicera) for an enhanced fragrance.
• Near an entrance or a window, to enjoy the fragrance.
• In an informal hedge with box or laurustinus.

The fragrance of Trachelospermum jasminoides is particularly intense in the evening, attracting moths.

Popular varieties

'Variegatum'

• Leaves variegated with cream-white.
• Compact habit, 3 to 5 m high.
• Fragrant white flowers.
• Ideal for small gardens and container cultivation.

'Tricolor'

• Leaves margined with pink and cream.
• Trailing habit, perfect for hanging baskets.
• Fragrant white flowers.
• Slower growth than the species type.

'Wilsonii'

• Vigorous and very fragrant variety.
• Larger and more leathery leaves.
• Abundant and prolonged flowering.
• Increased hardiness, down to -18°C.

'Star of Toscana'

• Slightly larger and more star-shaped flowers.
• Compact and dense habit.
• Intense fragrance.

Container cultivation

• Pot: large pot at least 40 cm in diameter, with drainage holes.
• Substrate: universal compost + compost + perlite for good drainage.
• Watering: more frequent than in open ground, let it dry between waterings.
• Location: full sun or partial shade, sheltered from cold winds.
• Overwintering: bring the pot into a veranda or cold greenhouse if temperatures drop below -5°C.
• Pruning: regular, to control the shape and stimulate flowering.

Specific issues in containers

• Yellow leaves: excess water or insufficient drainage.
• No flowering: lack of sun or pot too small.
• Slowed growth: fertiliser deficiency or root-bound.
• Pests: spider mites and scale insects more frequent indoors.

Pros and cons

Strengths

• Captivating and persistent fragrance.
• Hardiness and resilience.
• Evergreen foliage, green all year round.
• Easy to grow with moderate care.
• Adaptable: open ground, container, balcony.
• Attracts pollinators.
• Low susceptibility to disease when properly cultivated.

Limitations

• Sometimes slow growth in the early years.
• Susceptible to powdery mildew and rust in humid conditions.
• Can become invasive without regular training.
• Sensitive to late spring frosts on young shoots.
• Less abundant flowering in cold or low-sun climates.

Verdict: an excellent fragrant climber for most gardens, provided it is given a suitable support and sufficient sunlight.

FAQ — Frequently asked questions

What is the best time to plant?

Spring (March to May) or autumn (September to November), outside periods of frost or intense heat.

Can it be grown in a cold climate (USDA zones 5-6)?

Yes, by planting it in a sheltered spot (a sunny wall), mulching the base in winter and protecting the base with horticultural fleece. The 'Wilsonii' variety is hardier.

How long before the first flowering?

A young plant may take 2 to 3 years before flowering abundantly. A well-established plant flowers every year from May to July.

Is the fragrance present all year round?

No, the fragrance is mostly intense during flowering (May-July). Some varieties such as 'Wilsonii' have a more pronounced and longer-lasting fragrance.

Can you hard prune to rejuvenate an old plant?

Yes, hard pruning in late winter (February-March) can rejuvenate an old plant. However, avoid pruning more than a third of the foliage to avoid weakening it.

Does the plant need winter protection?

In very cold regions (below -10°C), mulch the base with a thick mulch (dead leaves, straw) and protect the base with horticultural fleece.

Further reading

• Trachelospermum jasminoides — Wikipedia
• Practical guide — Jardiner Malin
• Advice from Promesse de Fleurs