Seeds (Hibiscus sabdariffa)

Roselle (Hibiscus sabdariffa) is the true source of Egypt's famous karkade. Its tall, reddish stems carry pale creamy blooms that fall to reveal fleshy, deep-crimson calyces with a bright, tangy-tart flavour. Dried and steeped, they make the iconic ruby-red hibiscus drink served hot or chilled, and the calyces also shine in jams, syrups and sauces. The plant doubles as a striking ornamental in any sunny garden.

Planting

Direct-sow or start seeds in spring (March-April), as roselle needs a long, warm, frost-free season of about 6 months to mature. Soak seeds in water for roughly 24 hours, or lightly scarify and soak in hot (not boiling) water, to speed germination. Sow about 1.3 cm deep into moist soil; seeds sprout in 5-10 days at a soil temperature of 24-29 C. Space plants about 45 cm apart in rows about 90 cm apart. Raise seedlings in flats and transplant after 4-6 weeks, only once all frost danger has passed. When direct-seeding, sow a few seeds per spot and thin to the strongest seedling at 5-8 cm tall.

Fertilizing

Work compost into the soil at planting and apply fertilizer about 2-4 weeks after planting, guided by a soil test. Add a phosphorus source to support calyx development, and avoid excess nitrogen, which encourages leafy growth at the expense of flowering.

Care

Give roselle full sun for strong growth and good calyx production; too little light gives weak plants and poor blooming. Provide well-drained soil with consistent, plentiful moisture, especially during dry spells, never letting it dry out while growing. Rotate planting sites and mulch to suppress root-knot nematode, the most serious pest; watch for foot, stem and root rots in wet soils, and spider mites in hot, dry weather. As days shorten in autumn, blooms drop and red calyces form; harvest them plump, tender and crimson about 8-10 days after they appear.