Last updated on January 22nd, 2022
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These beautiful plants are evergreen climbers that produce vibrant red, purple or pink bracts. These are usually produced from the early Summer through until 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 notice 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 will 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 during the summer, however, they will 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 originates from the warm climates of South America and as such, needs 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 re-establish themselves in the spring.
If grown in a conservatory, they need to be planted in good quality compost and a granular fertiliser 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 milder. They need a dry protected site in well-drained soil. However, trying to grow one outside is always a risk and they could be killed at any time from the cold winter weather.
As they start to put on new growth, (usually around February-March) start watering them more frequently, keep the soil damp and allow the soil to become a little dry before watering again, being very careful not to rot the roots. If your Bougainvillea needs re-potting then this is the perfect time to do this.
Once your plant is growing nicely (around April) begin to water it freely and feed with a high in nitrogen feed.
When your Bougainvillea starts to produce bracts you will need to change to a balanced feed that you should apply weekly. If you want to grow your plant outside during the summer move it to a cooler sunny spot to allow the plant to adapt to the cooler climate (keep above 10°C) before relocating it permanently. Once the risk of frost has passed, usually around the beginning of June, you can move the plant outside permanently to a sunny location and water frequently.
Growing Bougainvillea in pots
If you want to grow Bougainvillea in pots then we would recommend using soil-based composts such as John Innes 3 and only pot them on when they become heavily root-bound. Bougainvillea plants 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 too quickly. Pot on in the spring before the new growth begins and 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 your Bougainvillea flowering
Bougainvillea will flower all summer if cared for correctly with you firstly ensuring that 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 good colour, they will 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 colourful bracts and keep them flowering for longer. Ensure you also feed them with a balanced fertiliser because this encourages more flowers. Do not continue to use the same high in nitrogen feed as this will encourage foliage growth rather than blooms.
Bougainvillea will flower up to 3 times a year. This can be further encouraged by feeding again with the high in nitrogen feed (when the bracts have dropped) to encourage another flush. When the next lot of bracts show good colour again, change to a potassium feed. After each flush or bracts have finished it’s 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 allowing the soil to become dry between watering sessions and watering 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 they will probably lose their leaves. Ensure they are kept dry if you choose to do this.
How to propagate Bougainvillea cuttings
Bougainvillea cuttings can be taken in summer or in winter. If you are taking the cuttings in summer you need to take semi-hardwood cutting with a heel, or you can take a hardwood cutting in the winter. In the winter they are best placed in a propagator with bottom heat to encourage rooting.
One of the best techniques for propagating Bougainvillea is via a method known as layering, which can 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. Layering is where you encourage a part of the plant to root whilst still being 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 layering is.
Standard and bonsai Bougainvillea
Bougainvillea is commonly used as a climbing house plant, grown on a strong trellis or frame, although they can also be trained as standards and are commonly grown as bonsai trees.
Bougainvillea is generally disease-free but they can be attacked by common pests, such as red spider mites, aphids and mealybugs.
Bougainvillea needs to be pruned either in the late summer (after flowering) or early spring before the new growth begins. It is essential that they are pruned before any new growth starts as they flower on new growth, and if you prune away the new growth you will be cutting the growth that produces the bracts. New falling shoots can then be tied to the frame.