|Official Plant Name||Bougainvillea|
|Toxicity||Sap is mildly toxic|
|Flowers||Bright showy flowers and bracts|
|When To Sow||June, July, August, September|
|Flowering Months||June, July, August, September|
|When To Prune||February, March|
4 – 8M
1 – 1.5M
June – September
Most Soil Types
Moist but well drained
Neutral / Acidic
If you’re looking to add an explosion of colour to your greenhouse or garden borders during summer, tropical Bougainvillea, with its bright green leaves and vivid magenta bracts, might just be the perfect choice.
This South American evergreen climber favours a hot climate and will struggle to survive frost, so if growing outside in the UK, it must be brought inside during winter. Growing it in a pot or container will allow you sufficient control of its environment for it to flourish.
Alternatively, a heated greenhouse provides the ideal environment for a bougainvillea to thrive, being warm and with direct sunlight protected by glass. You could also grow the plant exclusively inside, in a warm conservatory or on a sunny windowsill, and attach it to a trellis for support as it climbs.
Read on for our full guide on how to grow and care for bougainvillaea in the UK, as well as answers to many frequently asked questions. Whilst it may not be the easiest plant, with the right knowledge, there’s no reason your home or garden can’t be filled with beautiful bougainvillea blooms every summer.
Background, Origins & Varieties
Bougainvillea is a tropical vine that is native to Central and South America, including Peru, Brazil and Argentina, and is thought to have been first introduced to Europe in the early 19th Century. These days, it is grown in many warm climates around the world, from Florida to Greece, and is the national flower of Grenada.
Bougainvillea is characterised by bright green foliage, with curved, black-tipped thorns and tiny white flowers found at the centre of the colourful blooms. These sought-after vivid blooms are actually paper-thin bracts (coloured leaves).
Providing it has plenty of sunlight, the plant will re-flower several times during a UK summer, dropping its bracts each time. Bracts are most commonly found in shades of pink, magenta and purple, although many other colours also exist, including white, yellow, orange, red, and two-toned varieties.
Larger varieties of bougainvillea can reach up to 10 metres tall with support, and 10 metres wide if grown as groundcover. There are also dwarf cultivars that are unlikely to top 1 metre tall or wide. Of the over 250 varieties of bougainvillea that exist, only a couple are commonly cultivated and grown in the UK.
A good one to look for is ‘Barbara Karst’, which has bright magenta bracts and is one of the hardiest varieties, most likely to succeed in a UK climate. Low-growing B. glabra and B.buttiana (a hybrid) are two of the best choices for hanging baskets and containers.
Feeding, Care & Growing Tips
Bougainvillea should be planted, or, if necessary, re-potted, in early spring. We recommend planting in a container, with plenty of room for the root system. Bougainvillea favours a slightly acidic soil and needs plenty of nutrients. Use a well-rotted compost and a loam-based fertiliser, such as John Innes.
The plant requires full sunlight (at least 6 hours a day), although it should be protected by glass from direct light during summer. It also needs heat – you should place it outside only in late spring and summer. Otherwise, keep it indoors or in a greenhouse, ensuring the temperature of its surroundings stays above 10°C.
Bougainvillea does not have a high water requirement. You should water it regularly whilst it’s growing (when the soil starts to feel dry), but once matured, a thorough watering every 2-3 weeks during spring and summer should be enough. Use pH-neutral rainwater and add a high-potassium liquid plant feed to encourage blooming, if necessary.
Be careful not to over-water, as this will cause the plant to replace flowers with an abundance of green leaves and can also lead to root rot. Once the flowering period is over, around September, the plant will go into winter dormancy, and should only be watered very occasionally – although refrain from leaving it completely dried out for a long period of time, and water immediately if it starts to wilt.
In order for a potted bougainvillea to thrive indoors, you will need to tie it to a trellis, or other support system. This should be inserted into the soil upon first potting of the plant, to avoid damaging the roots later down the line. See below for more information on how to train bougainvillea on a trellis.
Habitat & Growing Conditions
Bougainvillea’s natural habitat is the tropical and sub-tropical, coastal areas of Central and South America. In these environments, the plant receives lots of sunlight, and benefits from high temperatures and humidity. In warmer climates, bougainvillea will flower practically year-round, not just in summer.
Bougainvillea grows in nutrient-rich soil, in areas with plenty of space to accommodate its root system (which can be quite significant on a larger variety). It prefers a drier soil with good drainage, as too much water can cause the roots to rot, and it does well in periods of drought. As the plant is native to coastal areas, it also has a higher-than-average tolerance to salt.
How To Train Bougainvillea On A Trellis
If you have planted your young bougainvillea in a container, and you want it to grow upwards, you need to provide it with the support of a trellis. This should be inserted into the soil when you pot your bougainvillea, to avoid damage to the roots at a later date.
Place the trellis behind the growing plant and use plant ties to loosely tie the vines to it, approximately every 30cm. Keep adding more ties as the plant grows – make sure you tie them tightly enough to secure the weighty branches. When it reaches maturity, it will be ‘trained’ and will not require further ties, unless you wish to change the direction of growth.
Pruning your bougainvillea is essential to encourage new growth and flowering. The best time to prune is in late winter / early spring – the end of February is usually about right. The aim is to prune before the new year’s growth begins in March, as this will ensure your plant is in the best possible position to flower.
Take this opportunity to re-shape your bougainvillea, removing any damaged or wayward branches, and setting it up for how you want it to grow. Limit overall pruning to a maximum of 50% of the plant, and always wear gardening gloves when pruning, to protect yourself from the thorns.
As well as this hard pruning prior to the growing season, you can also undertake a lighter pruning after each blooming in summer. This will encourage a second, or even third wave of bracts before the season is out.
Where To Buy Bougainvillea
Bougainvillea can be purchased from many garden centres or online specialists. Remember to look for a low-growing variety that does well in a container. If you already have an existing plant, you can also grow another from cuttings.
Common Diseases & Problems
The most common problem that occurs with bougainvillea is wilting and leaf drop, as a result of it being exposed to too low temperatures. Prevent this by bringing the plant inside during the winter months, and ensuring the surrounding temperature doesn’t drop below 10°C.
Other than that, bougainvillea is generally fairly hardy – it can survive with limited water, and there are not many diseases that are common to it. It may, however, succumb to some general pests, such as whitefly, aphid and red spider mite. Whitefly can be a particular concern as they favour a warm climate, such as the one you’ll be providing for your bougainvillea.
Visible signs of whitefly include the tiny white bugs themselves, the sticky honeydew substance they produce, and the black mould which develops as a result of the honeydew. An infestation can be controlled biologically, by introducing Encarsia Formosa (parasitoid wasps) to the environment, or by using an organic insecticide.
Frequently Asked Questions
How Big A Pot Do I Need For Bougainvillea?
How big a pot your bougainvillea needs will depend on the variety you are growing. Providing you choose one of the lower-growing varieties, such as those specified above, which have smaller root systems, bougainvillea can flourish in a relatively small container.
You can start out with a small pot, and simply re-pot the plant into a larger container if and when it becomes necessary. Just be careful not to damage the root system when you do this. Make sure that any pot used has at least one drainage hole, as bougainvillea does not like water-logged soil.
How Can I Grow Bougainvillea On A Fence?
The problem with growing bougainvillea on a garden fence in the UK is that you cannot move it inside during winter to protect it from freezing temperatures. Frost can cause wilting, significant damage to branches, or even kill your plant, depending on how badly the roots are affected.
If you decide to grow bougainvillea outside anyway, you should try to choose a sheltered area, such as courtyard, and cover the plant with a blanket on winter nights to keep the frost off. You are probably more likely to be successful if you live in an area of the UK with a milder climate, such as Cornwall.
In order to get a bougainvillea to grow on a fence, you should choose a tall, climbing variety. Follow the same procedure as attaching it to an indoor trellis – use soft plant ties to attach the branches to your fence posts or wire and continue to do so every 30cm until the plant reaches maturity. When it reaches the top, you can encourage it to grow back down/ along your fence using the same method.
How Can I Protect Bougainvillea From Frost?
Bougainvillea favours a warm climate and does not do well in temperatures below freezing (or temperatures under 10°C). Therefore, if left outside unprotected, it may not survive a UK winter – or at least, it could suffer significant damage.
To protectabougainvillea from frost, you should ideally grow it in a container, that you can move inside in autumn, before the first frost of the year. Try to find your plant a nice spot in a sunny conservatory or porch, where it can remain until winter is over.
If you’re growing bougainvillea in your garden, there are still steps you can take to try to protect it from frost. Monitor the weather forecast, and if a frost is expected, cover your bougainvillea with a blanket or plastic sheet. Use stakes to make sure it doesn’t touch the plant, but rather hangs over it like a protective tent. Remove the cover once the temperature rises.
Is Bougainvillea Poisonous To Dogs?
Bougainvillea is considered mildly toxic to dogs and can produce symptoms such as vomiting and diarrhoea. If your dog is displaying any of these symptoms, and you suspect they may have eaten bougainvillea, seek veterinary advice immediately. Minimise the risk of harm by keeping your dog away from bougainvillea plants.
Are Coffee Grounds Good For Bougainvillea?
Bougainvillea favours a rich soil with a slightly acidic pH. As fresh coffee grounds are highly acidic, it is often thought that adding a limited amount (up to 20% of total compost) to the soil around a bougainvillea can be advantageous to the plant.
Why Is My Plant Dropping Flowers?
There are several reasons why your bougainvillea may be dropping flowers. It could be that the temperature has dropped too low – bougainvillea plants need to be kept warm. In the event of an unexpected cold snap, make sure to bring your plant inside.
It could also be that your plant doesn’t have enough water. Although bougainvillea favours a drier soil, it still needs water to bloom. Do not allow the soil to dry out completely in the flowering season and give it a good drink at least every 2-3 weeks.
Make sure also that your bougainvillea is getting enough sunlight. It should have access to direct sunlight for at least 6 hours a day. If you’re confident all these requirements are being met, try adding a potassium-based liquid fertiliser to the soil, to give it a bract-strengthening nutrient boost.
April is a freelance writer who specialises in writing about home and garden design and the environment. She is an avid wildlife-enthusiast and adventure-seeker, and feels happiest when in the Great Outdoors.