Clivia are frost tender and can be damaged by temperatures below 5°C (40°F). They should be grown as a houseplant, in a conservatory or warm greenhouse and do best in bright, filtered or indirect light. Avoid direct sun in summer, which may scorch the leaves, and place pots away from radiators or other sources of heat.
Pot up in well-drained, loam-based John Innes No 2 compost mixed with multi-purpose compost or additional leaf mould and grit, although any good potting medium should be satisfactory. Do not plant too deeply – the neck of the bulb should be above soil level.
For flowers to form, a cool period of 10°C (50°F) is needed from November to February. After this, water sparingly, applying a balanced fertiliser weekly until the flower buds form; then move to a well-lit position with a temperature of 16°C (60°F).
After flowering, remove spent flower stems near the base, unless seed is required, and reduce watering. Water sparingly through winter, but do not allow the containers to dry out.
Repotting, where necessary, can be carried out in early spring using a slightly larger container. Clivia flower best when well established in containers at least 20cm (8in) in diameter. Leave to grow on for several years undisturbed and top dress annually with fresh potting compost.
Clivias by Harold Koopowitz (Timber Press 2002, ISBN 0881925462)
Grow Clivias: A guide to the species, cultivation and propagation of the genus Clivia by Graham Duncan (National Botanical Institute, Kirstenbosch 2002, ISBN 1919684379)
These books are also made available through the RHS Lindley Library.