Tropical Plants

Bougainvillea: Questions and Answers

Despite its tropical appearance and although it requires a little special care, bougainvillea is not as difficult to grow as you might imagine. You simply need to know its secrets for it to become covered in colorful bracts. Here it is, in the form of a fun little questionnaire!

Image: Charlotte Harrison on Unsplash

Some horticulturists say that bougainvillea is a climbing vine, others say it is a shrub. Who is right?

There are some 17 species in the genus, but those grown in Quebec are almost all complex hybrids involving three main species: Bougainvillea glabra, B. peruviana and B. spectabilis. All three are climbing shrubs. In the tropics, bougainvillea climb tall walls, sometimes up to three or four stories high, or even to the tops of trees. In homes, however, it can rarely be allowed to reach such proportions: instead, it’s pruned into the shape of a shrub. Moreover, the stems, weakly or strong and thorny, depending on the cultivar, are remnants of its former life: they helped it to cling to rough surfaces.

Is it true that bougainvillea is not grown for its flowers?

The true flowers, small and white or yellow, are unattractive and fall off quickly. However, to attract hummingbirds, which love brilliant colors, the plant has, over its long evolution, developed colorful leaves, called bracts, which surround the insignificant flowers. Thus, the hummingbird, attracted by the bright color of the bracts, approaches and discovers the tiny tubular flowers filled with nectar. The advantage for the gardener is that because a bract is actually a leaf, it lasts longer than a flower. Thus, the “flowering period” can easily last three months and sometimes even six!

Image: Mike Castro Demaria on Unsplash

Are there many varieties of bougainvillea?

Hundreds… but few are found in commerce. Besides, they are often sold without a name, just based on the color of the bracts. There is a wide range of colors – red, orange, yellow, purple, pink or white – as well as cultivars with double bracts.

Since bougainvillea is of tropical origin, should it be kept in the house at all times?

In the wild, Bougainvillea grows in the mountains, it actually prefers rather cool temperatures, especially during its resting period. Ideally, it is kept at around 10 to 15C at night during the winter.

In summer, on the other hand, it is placed outdoors, where the greater air circulation and the higher light intensity stimulate faster and more vigorous growth. However, place it in the shade when you take it out into the garden, then gradually increase its exposure to the sun until it is in full sun or light shade. It can burn if exposed to intense sunlight too quickly.

Can it flower if it stays in the house all year round?

Yes, but often it flowers less. In fact, it requires very high light intensity to flower well. A glass roof or south-facing room, with large windows or a skylight, is often necessary.

What is the flowering time?

In the wild, it flowers in summer. Hybrids are, however, capable of flowering repeatedly, usually taking three months of rest after a flowering cycle. In warm countries, it is possible to find bougainvillea in bloom 12 months a year!

Does it need a lot of watering?

Yes… but only during growth periods. Abundant watering as soon as the soil dries out is very suitable. In fall and winter, it can be allowed to dry out further between waterings, to the point where its foliage begins to wilt. A rest period helps stimulate bougainvillea flowering.

Do they prefer rich soil?

No, actually bougainvillea prefers regular potting soil. Fertilizers, especially those high in nitrogen, stimulate rapid growth but hinder flowering.

In what season can bougainvillea be repotted?

They can be repotted at any time, but the best time is early spring or fall, either just before a new growth cycle or immediately after.

Image: Pisauikan on Unsplash

The growth is so overwhelming that at some point it’s necessary to prune to control the development. When should we do it?

Usually, pruning is done in the fall, when the plant returns indoors. On the other hand, if the plant is still in bloom at this time, wait until after flowering. If the bougainvillea flowers out of season, in the middle of winter for example, which is not impossible, know that pruning after flowering is always appropriate. Even severe pruning does not harm flowering, since the plant flowers on new wood.

Sometimes gardeners complain that their bougainvillea does not bloom. What could be the reason?

Bougainvillea absolutely need a period of almost dry rest, at cool winter temperatures (less than 15°C at night), and also at high light intensity. Kept under normal indoor temperatures (18°C and above at all times), watered too abundantly, especially under low lighting, it is very possible that they will not bloom.

In addition, it flowers more abundantly when it’s a little cramped in its pot and the soil is not too rich: people who repot regularly in larger and larger pots and who fertilize too much will get lots of beautiful leaves, but very few colorful bracts.

Why do their leaves fall?

It naturally tends to lose a lot of leaves in the fall, at the start of the rest period. Their fall is therefore natural and is not necessarily a sign that there is a problem. On the other hand, a massive leaf fall at other times often indicates a lack of light.

Image: Mollie Moran on Unsplash

Julie Boudreau is a horticulturist who trained at the Institut de technologie agroalimentaire in Saint-Hyacinthe, Québec. She’s been working with plants for more than 25 years. She has published many gardening books and hosted various radio and television shows. She now teaches horticulture at the Centre de formation horticole of Laval. A great gardening enthusiast, she’s devoted to promoting gardening, garden design, botany and ecology in every form. Born a fan of organic gardening, she’s curious and cultivates a passion for all that can be eaten. Julie Boudreau is “epicurious” and also fascinated by Latin names.

2 comments on “Bougainvillea: Questions and Answers

  1. Bougainvillea do not actually climb actively. They produce tall lanky shoots that lean onto support. From there, the produce more of the same that do the same higher up. They grow through canopies of large shrubbery and small trees so that they can be difficult to pull out. However, they do not climb bare walls without some sort of support to hold them in place.

  2. Victoria Coward

    Thank you. Your timing was perfect for me. I’m planning to move a new purchase plant from a sunny window to a hot sunny deck. Our nights in West Kelowna are warming up to 10 to 15, days are 25 -26.
    Should I leave the plant in the nursery pot or transplant up?

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