Bougainvillea

What looks like a flower on a bougainvillea is in truth three coloured bracts — hence the German name Drillingsblume, triplet flower. The actual blooms sit as small white tubes at their centre. Because bracts last longer than petals, each colour wave holds for several weeks.

The trade is dominated by Bougainvillea glabra, the most reliable bloomer in containers, alongside the more colourful but touchier varieties of Bougainvillea spectabilis and numerous hybrids. The classic magenta-pink is toughest; apricot and bicoloured varieties need more warmth.

The key to flowering is the right dose of stress: bougainvilleas bloom most richly in full sun with the soil drying slightly between waterings. Plants kept constantly moist push only foliage — the most common reason a bougainvillea at home never flowers like it did on holiday.

At the same time the root ball must never dry out completely, or the plant sheds leaves and bracts overnight. This narrow band between too wet and too dry makes it a plant for attentive gardeners. After leaf drop it usually shoots again, though, so do not discard it prematurely.

The shoots are thorny and grow as scramblers — they do not climb by themselves but want tying to a trellis or hoop. Pruning after each flowering wave keeps the plant compact and triggers the next wave, since flowers form on new growth.

Overwinter it bright and cool at around five to twelve degrees, watered very sparingly; leaf drop in winter quarters is normal. From mid-May it can go back out — harden it off in shade first, or the leaves grown indoors will scorch in the first sunny week.