Bougainvilleas (Bougainvillea) are popular tropical climbing shrubs from the Nyctaginaceae family, which are cultivated in Central Europe exclusively as tub plants. We also call them triple flowers. They bear their unusual botanical name in honour of the French navigator and circumnavigator Louis Antoine de Bougainville, who lived in the 18th and 19th centuries.
All bougainvilleas originate from a relatively small area that stretches along the Andes from Ecuador to Brazil. They grow there predominantly in summer-dry forests, where they throw off its foliage with beginning of the dry-time and drive out again afterwards again. The gardening assortment consists mainly of different varieties and hybrids of the Bald Triple Flower (Bougainvillea glabra). A little rarer in culture is Bougainvillea spectabilis. There are still approximately 15 further types without horticultural meaning.
Appearance and growth
The tropical climbing shrubs are so-called spread-climbers – they do not form special climbing organs, but climb up with the help of long, slightly spined shoots. With good care they flower with small breaks the whole summer through in strong, bright colors of white, yellow-orange over pink, pink and lilac until blood-red. Each inflorescence consists of three coloured bracts surrounding the creamy white tubular flowers.
The egg-shaped, tapering stem leaves disappear almost completely under the lush blossoms in summer. In their natural habitat and also in the Mediterranean region, the plants reach impressive growth heights of well over five metres as outdoor plants. In Central Europe they are cultivated exclusively as tub plants because of their sensitivity to frost. As such, they are rarely taller than three meters.
Location and substrate
Bougainvilleas need a warm and full sunny location, because even in semi-shade they have fewer flower buds. A rain sheltered place on the terrace is ideal, but bougainvilleas can also be cultivated all year round in the bright, heated winter garden. They grow best in a structurally stable, permeable pot plant substrate with sufficient mineral content. The addition of clay is also very good for the plants.
Bougainvilleas have a high water and nutrient requirement. It is best to place the pots in a saucer and pour them on hot days in the morning and late afternoon. A regular water supply during the vegetation period is very important, because the climbing shrubs quickly drop the leaves and stop growing when there is a lack of water. This is a natural adaptation to their original habitat, the tropical dry forest with pronounced rainy and dry seasons. From spring to late summer, Bougainvilleas should also be supplied with a phosphate-rich flowering plant liquid fertilizer every two weeks at the latest.
Bougainvilleas prefer a permeable pot plant substrate with a low humus content. The pot should be rather small, as this promotes flowering – in containers that are too large, the plants may only form leaves. The pot is repotted every two to three years in spring after being cleared out of the winter quarters.
If triple flowers are not cut, meter-long shoots with weak branching form, which only bear flowers at the ends. Therefore a strong pruning is recommended in autumn before wintering or in spring. The plants go through several flowering phases in one season, after which they should also be pruned again and again. By regular pruning, the plants can easily be kept at a height of one to two metres. So after a few years, when the guide drives are strong enough, they can do without climbing aids. Also an education as Hochstämmchen is possible.
Bougainvilleas do not tolerate frost at all and therefore have to be brought to their winter quarters in time in autumn. A bright location with temperatures between 10 and 15 degrees is ideal. When there is a lack of light, the bushes lose their foliage, but that is not a problem – they sprout reliably in spring. Water unleaved plants only so much that the soil does not dry out completely. The pot should not stand directly on a cold stone floor, but better on a wooden board or a Styrofoam plate.
The propagation is possible by cuttings, but hardly practicable for hobby gardeners, since one needs a cultivation bed with floor heating and usually several months pass, until the first roots show up. It is easier to plant individual shoots in spring. One leads a shoot segment into a separate pot with growing soil and keeps it evenly moist. A wound incision accelerates root formation.
Diseases and pests
All in all, bougainvilleas are quite robust. With dry-hot climate and lack of water, however, they are attacked by spider-mites occasionally. Scale insects can also occur, especially in winter quarters.
Whether potted plants such as oleanders or indoor plants such as orchids: The scale insect infests the most diverse plants. René Wadas, a herbalist, will give you his tips on pest prevention and control: Production: Folkert Siemens; Camera: Fabian Primsch; Editing: Dennis Fuhro; Photo: Flora Press/Thomas Lohrer
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