Bougainvillea is a hardy tropical vine that grows in areas where winter temperatures remain above 30 degrees F. (-1 C.). The plant usually produces three rounds of vibrant blooms in spring, summer and autumn. If you don’t have growing space or live in a suitable climate, you can plant bougainvillea in a pot. If you live in a chilly climate, bring potted bougainvillea plants indoors before the first frost.
Bougainvilleas need a bright sunny position, but protection from direct sunlight under glass and a minimum night temperature of 10°C (50°F). As large climbers they can be planted directly into a conservatory border or grown in large containers. These can be placed in the garden in summer but must be kept frost free in winter. Enrich border soil with well-rotted compost and a balanced granular fertiliser or controlled-release fertiliser such as Osmocote. Use loam-based compost like John Innes 3 for containers.
Spring and Summer
- Increase water in February-March as the increasing light levels and temperatures stimulate growth
- Maintain high humidity in bright periods to encourage buds to break
- Re-pot if necessary in early spring, using loam-based compost such as John Innes 3
- If containerised, place outdoors in full sun, ideally 18-21°C (65-70°F) at night, a few degrees warmer by day
- Once plants are growing strongly around mid-April, water freely and feed weekly with a high nitrogen liquid feed
- When bracts show colour, changed to a balanced liquid feed and move plants to cooler conditions (if possible to 10°C (50°F)) with good ventilation and protection from direct sun. This encourages the bracts to mature and persist longer on the plant. Cooler conditions may cause the leaves to droop for several days so water less frequently until plant adapts
- When bracts have dropped resume high nitrogen feed to encourage a second flush of bracts
- Change to a high potassium feed when bracts begin to show colour
Autumn and Winter
- Once flowering ends, usually in September, reduce frequency of watering, allowing the plant to become drier between watering and stop feeding
- From November, water occasionally but thoroughly
- Maintain a minimum night temperature of 10°C (50°F). Bougainvillea can be stored above freezing provided the compost is kept relatively dry but they will drop leaves
Pruning and training
Bougainvilleas require a trellis or pillar for support and can be trained as a standard and spur-pruned to restrict size. They flower on the current seasons growth so pruning in late winter or early spring, just before growth begins.
- Early in the season, bend and tie in young strong-growing laterals to check the vigour and stimulate bract formation
- After the bracts have fallen cut this long growth back by half to encourage a second flush of bracts in the late summer
- Plants should respond to hard pruning but old plants are better replaced
Propagate by semi-hardwood cuttings taken with a heel, in summer or hardwood cuttings in winter but with bottom heat 3-6°C (5-10°F) above the air temperature to encourage rooting.Layering in late winter and early spring is usually more effective and new plants will flower in 2-3 years.