Last updated on March 26th, 2021
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These beautiful plants are an evergreen climber that produce vibrant red, purple or pink bracts. These are usually produced from early Summer through to Autumn. The fabulous flowers can sometimes flower all the way through into December. The flowers are actually tiny, white and insignificant and it is actually the bracts that produce the attractive vibrant colours you see. If you look carefully you will see the tiny white flowers on the plant.
In the UK they are usually grown in a warm conservatory or in a heated greenhouse as they need a bright sunny location and a minimum nightly temperature of at least 10°C (50°F), any lower they lose their leaves. They are quite at home in large pots and planters, as they like to be slightly root-bound. These plants can be grown outdoors in the Summer but they need to be brought in before the frost and kept in a warm position during the winter. Inside warm conservatories they have been known to flower for up to 10 months.
Bougainvillea originate from the warm climate of South America and as such, need to be kept warm, above 10°C at night. They can handle the temperature dropping lower but they will lose their leaves and take longer to establish in the spring.
If grown in a conservatory, they need to be planted in good quality compost and a granular fertilizer should be added to encourage new healthy growth.
In some parts of the UK it has been possible to successfully grow Bougainvillea outside all year round. This is mostly in the southern parts of the UK in counties such as Cornwall and some parts of London where the conditions are generally warmer and winters more mild. They need a dry protected site in well drained soil. However trying to grow one outside is always a risk and they can be killed at any time by cold winter weather.
As they start to put on new growth, usually around February / March, start watering more often and keep the soil damp and allow soil to become a little dry before watering again being careful not to rot the roots. If your Bougainvillea needs re-potting then this is the time to do this.
Once your plant is growing nicely around April start to water freely and feed with a high in nitrogen feed.
When your Bougainvillea start to produce bracts you need to change to a balanced feed which you should apply weekly. If you want to grow your plant outside in summer move to a cooler sunny spot to allow the plant to adapt to the cooler climate (keep above 10°C). Once the risk of frost has passed, usually around the beginning of June move the plant outside to a sunny location and water frequently.
Growing Bougainvillea in pots
If you grow Bougainvillea in pots then use soil based compost such as John Innes 3 and only pot on when they have become heavily root bound. Bougainvillea actually like to have tight roots and should only be potted on into the next pot size up, so be careful not to go too big. Pot on in Spring before the new growth begins, they can be planted out in summer when the temperature is ideally above 18-21°C (65-70°F) at night and a little warmer in the day.
How to keep Bougainvillea flowering
Bougainvillea will flower all summer if cared for correctly, firstly ensure they are grown in full sun and kept warm. Once they are growing well usually around April / May then water regularly and feed weekly with a feed that is high in nitrogen.
When the bracts are looking well with a good colour, they benefit from being moved to a slightly cooler location still in full sun but also protected from direct sun with a little shade. This will help prolong the colorful bracts and keep them flowering for longer, ensure you also feed with a balanced fertiliser to encourage more flowers. Do not use the same high in nitrogen feed as this will encourage foliage growth.
Bougainvillea will flower up to 3 times a year and this can be encouraged by feeding again with the high in nitrogen feed when the bracts have dropped to encourage another flush. When the next lots of bracts show good colour again, change to a potassium feed. After each flush or bracts have finished its advised that you cut them back by about half to encourage more bracts.
What to do with your Bougainvillea in winter
Once they stop flowering, usually anywhere from September through to December, then we recommend reducing watering and allow soil to become dry between watering and water less frequently. If temperatures get above 10°C they will stay evergreen and provide some colour through the winter. However if you want to store them in a cooler area they will survive if kept frost free but will probably lose their leaves, ensure they are kept dry if you choose to do this.
How to propagate bougainvillea cuttings
Bougainvillea cutting can be taken in summer or in Winter, if taken in Summer you need to take semi-hardwood cutting with a heel or you can take hardwood cutting in winter. In winter they are best placed in a propagator with bottom heat to encourage rooting.
One of the best techniques for propagating Bougainvillea is by a method known as layering which an be done in winter. This will produce more established plants and you can have them flowering within 2-3 years. Layering is also one of the easiest ways to propagate plants as they don’t have to survive on their own like cuttings. Laying is where you encourage a part of the plant to root whilst still attached to the main plant. Some plants do naturally layer and take root. Have you ever seen a plant where a branch has touched the floor and started to root, this is an example of what laying is.
Standard and bonsai Bougainvillea
Bougainvillea are commonly used as climbing house plants grown on a strong trellis or frame but they can also be trained as standards and are commonly grown as bonsai trees.
Bougainvillea are generally disease free but they can be attacked by common pest such as red spider mite, aphids and mealybugs.
Bougainvillea need to be pruned either late summer after flowering or early spring before new growth begins. It is essential that they are pruned before new growth starts, as they flower on new growth and if you prune new growth you will be cutting the growth that produces the bracts. New falling shoots can then be tied to the frame.