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Jack in the bush

Chromolaena odorata · Asteraceae

The gardener's calendar

The right move for September

In autumn, ease off feeding and take the chance to clean up around jack in the bush and prepare for winter.

JFMAMJJASOND Planting

ID card

Common name
Siam weed, Chromolaena
Family
Asteraceae
Type
Shrub
Flowering
Summer to autumn, blue-violet flowers
Mature size
1.5 to 3 m in height
Growth
Very fast
Hardiness
Non-hardy, warm climates (tropical and subtropical)
Foliage
Evergreen, aromatic when crushed
Origin
Central and South America

Care

Light exposure

Plant Chromolaena odorata in full sun for generous blooming. It tolerates partial shade but remains less floriferous. This shrub appreciates warm, well-lit areas away from cold winds that can damage it.

Watering

Water regularly during active growth and flowering, keeping the soil moist but well-drained. Reduce watering during the dry season or winter depending on local conditions. Avoid waterlogging, which promotes fungal diseases.

Soil

This plant prefers rich, well-drained soil that is slightly acidic to neutral. It adapts to various soil types but appreciates added organic matter (compost) at planting time. Poor soil will naturally slow down its rapid growth.

Pruning and maintenance

Prune regularly after flowering to maintain a compact, bushy form. Remove dead, diseased, or overcrowded branches. Pruning encourages denser branching and better flowering the following year.

Fertilization

Apply balanced fertilizer monthly during the growing season (spring-summer). Reduce applications in autumn and winter. Excess nitrogen promotes foliage at the expense of flowers; prefer a formula higher in phosphorus and potassium.

Diseases and pests

Watch for mealybugs, spider mites, and aphids in dry climates. Poor drainage can cause root rot or fungal diseases. Ensure good air circulation around the plant and promptly remove affected leaves.

Did you know?

Chromolaena odorata, native to tropical America, has become a formidable invasive plant in Africa and Southeast Asia. Its name 'odorata' comes from its strongly aromatic foliage: when crushed, it releases a characteristic, sharp and herbaceous scent that can be pleasant or repellent depending on your preferences.

Where to buy it

Best planted in autumn so the roots settle in before summer, or in early spring once the frost has passed. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, October, November.

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Tips generated and checked by Viridia — adapt them to your local climate.