Bougainvillea is an extremely showy climbing plant with colourful papery bracts (modified leaves), hence the common name of “paper flower”. There are several colours available but the deep pink or purple still remains the most popular.
Bougainvilleas require room to grow and are therefore best suited to greenhouses or conservatories where they will also receive the good light they require. They can be grown directly into the greenhouse border or, if placed in a conservatory, grow them in pots. Placing the pots outdoors during summer would be beneficial to the plants but make sure they go back indoors well before there is any danger of frost.
You will most likely purchase a bougainvillea with bracts already developed. These will last for several weeks and new ones will continue to form. When all bracts have faded on each branch, prune that branch back by about half and more bracts should follow on the new growths that develop over the summer. Feed with a high nitrogen fertilizer to encourage growth but change to a high potash fertilizer when colour starts to show on the bracts.
In early autumn the bracts will stop developing and that is the time to start reducing watering and stop feeding. Keep the plants in a cool bright spot over winter. Around late February or early March prune the branches back by about a third and start to increase watering. When new growths appear start feeding again with a high nitrogen fertilizer, reverting to a high potash one as soon as colour appears in the bracts again. Remember, bougainvilleas flower on the new growths.
If your bougainvillea is to become a permanent feature in the conservatory or greenhouse, provide a suitable framework on which to train it. Plants in containers to move around can be fitted with a wig-wam style framework or trellis for the plants to climb around. Re-potting or potting on into a larger pot may be necessary every 2 or 3 years. Use a soil based compost such as John Innes No.3.