Hibiscus cannabinus aka Indian Hemp

Hibiscus cannabinus, or kenaf, belongs to the mallow family. Other names include Deccan hemp and hemp mallow. Its native home remains unclear. Sources suggest tropical Asia or America, but do not confirm either. People have grown it in Africa for about 6,000 years. Today, growers raise it across tropical and subtropical regions. They harvest it for fibre, food, oil, and traditional medicine.

Kenaf grows fast and usually serves as an annual crop. It can also live briefly as a woody-based perennial. Sources give heights from about 6 feet [1.8 metres]. The RHS garden range reaches 8–13 feet [2.5–4 metres]. Plants spread about 3–5 feet [1–1.5 metres]. The upright form has few branches, often with one main stem. Slender stems bear small spines and dark green leaves. Long stalks hold the leaves away from the stems. Upper leaves have lobes that spread like fingers. Lower leaves lack these lobes, and the foliage is deciduous.

Flowers appear from summer into autumn. Each has a funnel shape and a deep red centre. Most are pale yellow, though some are purple-red. They grow alone or in clusters along a flower stalk. The plant forms seed capsules after flowering. Useful Tropical Plants lists insects and bees as pollinators. It also reports that kenaf is self-fertile.

Outdoors, give kenaf full sun and a sheltered site. Use well-drained soil with a neutral to slightly acid pH. Long, hot summers help it flower well. Frost damages the plant, and RHS rates it H2. Containers allow growers to move plants indoors for winter. Indoors, provide bright filtered light, moderate humidity, and good airflow. Sow seed indoors in spring, or divide plants then. Plants grown as annuals need no pruning. Kenaf suits borders, bedding, large pots, and glasshouses. Under glass, watch for aphids, scale, mealybugs, and whitefly. Powdery mildew can occur; honey fungus is a rarer risk.

Cooked young leaves add a sour taste to soups. Seeds can be roasted or milled into flour. They also yield edible oil. Flowers and roots are edible, though roots are fibrous. The sources report no known hazards, rather than confirmed universal safety. Stem fibre supplies rope, sacks, and other coarse fabrics. Growers also use kenaf to limit erosion and improve soil cover.