Grow beautiful bougainvillea
With summer holidays on our minds, thoughts turn to exotic flowers of warmer countries, which we often dream of growing. Nothing is as vivid as expansive drifts of vibrant bougainvilleas in eye-popping colours – from yellow and orange to the more common purples and pinks.
A vigorous climber with arching stems armed with unexpectedly sharp thorns, it can reach 5m (16ft) or more in frost-free climates. Though we can’t hope to match this in our cool climate, with a little care we can recreate a little bit of Mediterranean magic here at home in the greenhouse, conservatory and even on the patio.
Up close and personal
In warm climates bougainvilleas grow freely, flinging arms of colour in all directions, covering the ground, scampering up walls and festooning slopes. Their colourful display isn’t provided by the flowers, which are small, tubular and creamy-white, but their surrounding leaf bracts. There are usually three bracts arranged in a triangle, with one or two flowers attached to each. The flowers don’t last long but the bracts stay bright and cheerful, long before the flowers open and weeks after the blooms shrivel up.
Facts on feeding
Although they grow in what seems to be dry soils, and they need sun and heat, it’s a mistake to treat them like cacti when growing them. Potentially large plants, bougainvilleas like plenty of water in growth and lots of food. Most are rather potbound when you buy them and can be put into slightly larger tubs. Use a good compost containing some loam, John Innes No 3 is ideal. Once growing, water frequently, though never allow them to sit in water, and apply a liquid fertiliser once a week right through to autumn. In spring, especially as plants come out of dormancy, give a balanced feed that’s relatively high in nitrogen to encourage strong stems. In June, switch to a high-potash fertiliser, which will help encourage flowering. If you buy a plant in bloom, use a general fertiliser, which will encourage more shoots to grow, rather than a high-potash one.
Pruning and care
Little pruning is needed in summer apart from cutting back the shoots that have finished flowering. When lightly pruned, it’ll encourage sideshoots that should produce flowers later in summer. In late winter and early spring they can be pruned in a similar way to a rose bush, cutting away dead stems, any that are badly placed and reducing the length of strong shoots. As with roses, very hard pruning may encourage strong stems that are unlikely to bloom except at the ends. This can be corrected by bending the stems over towards the horizontal.
Bougainvilleas are not especially prone to pests but aphids will attack the young shoot tips. In a greenhouse or conservatory they may be invaded by scale insects or mealy bug, which both suck the sap and secrete sticky honeydew. Both can be controlled with a systemic insecticide.
Sat in a pot on the patio, these tropical climbers scream summer. Just keep them frost free and you’ll have stunning displays
Year-long colour
When temperatures in winter can be kept above 10C (50F) the plants can be evergreen and have some bracts through most of the year, but if kept any cooler they’ll lose their leaves. This won’t damage the plants, which will be dormant in winter, when they should be kept almost dry and free from frost, in similar conditions to fuchsias and pelargoniums.
Choose the right site
It’s possible to grow them outside in only the mildest and warmest parts of the country. For everywhere else they need a sunny conservatory, sunroom or a greenhouse. Frequently sold on small wooden trellises, they can also be kept as houseplants on a sunny windowsill but they’ll eventually be too big and their thorny stems can play havoc with net curtains! A plant in bloom can be placed outside on a sunny patio, where the bright bracts will give your garden a touch of the Mediterranean.