To increase the amount bougainvillea blooms and to stimulate flowering, locate bougainvillea in full sun but ensure it is exposed to fewer then 12 hours of daylight as they are short day plants. Watering potted bougainvillea once a week crates the optimal balance of moisture and drought stress to encourage more flowers.
Bougainvillea are native to Brazil and fewer hours of sunlight stimulate flowering as shorter days signal to the bougainvillea it is the optimal time to display its flowers to coincide with the right environmental conditions at that time of year.
Shorter days is one of the most influential factors for increasing bougainvillea blooms. Keep reading to learn the 7 ways to increase the number of flowers and for flowers that are display for longer…
1. Bougainvillea Blooms More with Shorter Day Lengths
Bougainvillea are a little different! Whilst they require daylight, they will bloom more if they have shorter day lengths.
This peculiar feature is a result of adaptations in tropical environments where, in the dry season, the days are shorter than the nights which signals to the bougainvillea it is the right time of year to flower.
It is, therefore, pertinent to replicate these conditions. Bougainvillea prefer at least 12 hours of uninterrupted darkness to flower.
Finding the best spot for your bougainvillea can therefore be a little challenging for those who live in northerly latitudes.
For example, the UK can have as many as 15 hours of daylight a day or in New York, where peak sunlight hours can reach as many as 16.
Ensure there is no artificial light at night that interrupts the preferred 12 hours of darkness.
If you’re particularly keen (like me), this could be helped through using a cloche, horticultural fleece or even an umbrella to shade your bougainvillea, to replicate its natural conditions for flowering.
It is important to note that bougainvillea still requires lots of direct sunlight to flower but the hours of sunlight should be restricted to slightly fewer then 12.
Encouragingly, bougainvillea are capable of flowering all year round if your climate has a mild winter, e.g. for those of you in a Mediterranean climate, but regardless of location, they will flower more with 12 or more hours of darkness.
Fun Fact: Bougainvillea flowers are actually small and delicate. The large colorful petals are not actually flowers but bracts which is a specialized leaf that has the function of attracting pollinators.
2. Water Less Often for More Flowers
Bougainvillea love the heat and dry conditions – they are native to Brazil after all!
Therefore, it is important that they are not watered too often.
Bougainvillea are drought tolerant and should be treated a little different from your hydrangea and rose displays, but a little more like your lavender and Mediterranean herb collection.
Typically water your potted bougainvillea once a week with a through watering, but refrain from watering if the soil feels moist to a fingers depth. The soil should just feel as though it is drying out before watering again.
Watering too often will invoke a stress response from your plant and will ultimately lead to fewer blooms. Watering less will solicit some drought stress and will stimulate the bougainvillea to display more flowers. This is the bougainvillea’s fascinating survival response, as blooms are the plant’s way of reproduction.
I personally water my potted bougainvillea once a week – and I am rewarded with this display of blooms.
Mature bougainvillea vines planted in garden boarders often do not require watering unless they are small plants that do not have an established root system yet or in exceptional drought.
(It is important to note that you should water bougainvillea different amount at different times of year. Read my article for how to water potted bougainvillea).
3. Direct Sunlight Promotes Bougainvillea Blooms
Direct sunlight is a must for bougainvillea. As you can imagine, they get this in abundance in their native Brazil – so it is really important to recreate these conditions as best you can in your garden, wherever you are.
To do this, plant your bougainvillea in a sunny spot where they can absorb at least 6 hours of direct sunlight. This will ensure your bougainvillea has enough sunlight to stimulate a good display of flowers.
A good idea is to plant your bougainvillea in pots; this enables you to move them to full sun areas during the changing seasons.
Furthermore, you can then move these pots indoors during the winter if you live in a non-Mediterranean environment. This will help protect the plant from the cold and potential frosts.
(Bougainvillea often lose their leaves in Winter if they are outside of their optimal climate, however the leaves can regrow in Spring with the right care, read my article on bougainvillea losing their leaves for how to save your bougainvillea).
Remember, it is important to consider the shorter day length for increased blooms, as well as the intensity of the sun.
4. Warm Temperatures Increase Flowering
Warmer temperatures mean increased bougainvillea blooms. This is particularly important for those of you who live in cooler climates.
Night temperatures should be, optimally, around 65°F (18°C). However, bougainvillea are relatively hardy and have good adaptable qualities and can manage cooler (but not cold!) night-time temperatures and still display lots of flowers.
Place your bougainvillea in a sheltered location so that cold winds to not stress the plant.
If the nights are too cold, the plant can become stressed. In colder climates it is important to grow your bougainvillea are in pots and bring them indoors in the Winter as they cannot tolerate severe frost.
Place your pot in a sunny window spot so that they get the indoor warmth and the light of the sun for optimal blooms.
5. Use Less Fertilizer for More Flowers
Using too much fertilizer will cause your bougainvillea to grow lush green foliage at the expense of flowers!
If your Bougainvillea are well established and planted out in borders, they should require little to no fertilizer. They are likely thriving in that position because they have well drained soil – rather than fertile soil (see point 6 on drainage).
If your Bougainvillea are in pots, then using some half strength all purpose fertilizer would be pertinent to ensure they have the correct nutrients for flowering and not too much nitrogen (the chemical responsible for that lush green foliage). Apply the fertilizer at the start of spring once any threat of cold weather has passed. Remember, Bougainvillea are not cold hardy!
I personally have seen great results by stopping using fertilizer when the day lengths begin to shorten as the ‘stress’ of less available nutrients also stimulates flowering.
This is in the same way that drought stress can also incentivize the bougainvillea to prioritize reproduction-by flowering- rather than growth on its leaves, roots and vines.
6. Well Draining Soil Increases Blooms
As noted, bougainvillea have adapted to growing in soil that has good drainage. They do not tolerate boggy, over-watered soil as the roots can rot. To increase blooms, make sure your bougainvillea has good drainage.
Ensure your soil has good drainage by adding horticultural grit – this will help to replicate the well draining soil conditions the bougainvillea has in their native Brazil.
When creating a potting mix for bougainvillea use the same formula as potting for Mediterranean herbs with one third horticultural grit and 2 thirds peat free compost to ensure the optimal balance of soil moisture for the bougainvillea to display flowers.
If you are planting in pots, make sure the pots have drainage holes in the base to allow excess water to escape efficiently after watering. Pots may, therefore, be the location of choice for bougainvillea as you can control the drainage more so than what you can do with your garden borders.
7. Pruning Bougainvillea for More Flowers
Bougainvillea displays its flowers on new seasons growth rather then old wood, therefore to increase your bougainvillea flower display it is important to prune your bougainvillea in either late Winter or early Spring before Spring growth starts growing.
If you don’t prune your bougainvillea then they can grow leggy with fewer flowers so some tactical pruning is always recommended.
Pruning should not be too heavy as this can divert too much energy to growth new shoots and vines but rather light pruning is best for stimulating flowering and can help you keep the bougainvillea in a desired shape on your trellis or support structure.
Watch this helpful YouTube video for how to prune your bougainvillea to increase the concentration of flowers:
(For all more tips and all the best practices of bougainvillea care, read my article, how to care for bougainvillea in pots).
Key Takeaways:
- To increase the amount of bougainvillea flowers ensure bougainvillea has 12 hours of uninterrupted darkness each night. Bougainvillea are short day plants that require fewer hours of daylight then darkness to stimulate flowering. Water bougainvillea less often in Summer to create drought stress which promotes blooms.
- Bougainvillea originates in the hot and dry conditions in Brazil, where it flowers more in at least 6 hours of direct sunlight or more. Too much shade prevents bougainvillea from blooming. Bougainvillea require direct sun to stimulate flowering yet also requires more hours of darkness then daylight.
- Apply a half strength fertilizer to potted bougainvillea in the Spring to ensure the bougainvillea has the nutrients it requires to display flowers. Scale back the use of fertilizer as soon as flowers emerge as a slight nutrient deficit causes stress which promotes flowering.
- To increase the amount bougainvillea flowers, prune the vine in the early Spring. Bougainvillea flowers on new growth so pruning in Spring helps to stimulate new growth on which the bougainvillea displays its flowers.