Croton is a tropical shrub grown entirely for its foliage: leathery, glossy leaves in combinations of red, orange, yellow, green and near-black, in shapes from broad ovals to narrow corkscrews, unlike anything else in a garden. It is perennial only in zones 10 and 11, where it reaches 3 to 8 feet; everywhere else it is a container plant or a seasonal annual, moved outdoors after the last frost and brought in before the first cool nights of autumn.
The colour depends on light: full sun gives the brightest leaves, and shade turns them green. Keep the soil consistently moist in rich, well-drained mix, since it wilts dramatically when dry, and feed lightly through summer. Bring containers indoors when night temperatures approach 55°F; it drops leaves in protest below that and again whenever it is moved, then settles. Indoors it wants the brightest window and a humid spot.
The bold foliage carries summer container plantings and works as cut foliage in late-summer arrangements. The milky sap is an irritant, so wear gloves when cutting, and the plant is toxic to pets if chewed. Spider mites and scale are the indoor pests. It is native to Malaysia and the Pacific islands.
Crown Rot
Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.
Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.
Botrytis (grey mould)
Grey fuzzy mould on petals and stems, worst in cool wet conditions.
Remove affected parts immediately. Improve air circulation. Avoid overhead watering. Apply copper fungicide if severe.
Croton Anthracnose
Tan to brown dead patches on leaves, often along edges or tips, sometimes with small dark fruiting spots. Affected leaves yellow and drop.
Remove and discard infected leaves. Avoid wetting foliage when watering and improve air circulation. Apply a copper-based fungicide if it spreads.
Spider Mites
Tetranychus urticae →Fine stippling or bronzing on leaves, faint webbing on undersides, foliage drying out during hot, dry weather.
Spray foliage with a strong jet of water to dislodge mites. Apply insecticidal soap or horticultural oil to leaf undersides; repeat every 5–7 days as needed.