In warm climates, the tropical perennial plant known as bougainvillea can bloom from as early as May through the end of the fall.
The stress on the plant prevents the bougainvillea from blossoming. The optimal time for bougainvilleas to flower is when the day is less than 12 hours long and they receive 6 hours of direct sunlight. Bougainvilleas cannot flower in wet soil, and excessive fertilization results in luxuriant foliage but few flowers.
Continue reading to learn more about the reasons why your bougainvillea might not be blooming and what you can do to guarantee a good flower display the following season.
1. Too Much Water Prevents Flowering
Because they can withstand dryness and do well in drier soils with infrequent watering, bougainvilleas.
Gardeners usually make the error of trying to water regularly so that the soil is consistently moist, similar to how roses or hydrangeas do.
More frequent watering of bougainvilleas stresses the plant because it isn’t getting the hot, dry conditions it prefers in its natural habitat, which leads to fewer blooms.
It is best to treat bougainvilleas as having the same watering needs as Mediterranean plants like lavender and wait to water them until the soil is just barely beginning to feel dry for the winter.
In their native South America, they flower during the dry season, so this mimics those conditions, and the water stress encourages the development of the vibrant flowers (and bracts).
During the Spring and Summer, I personally water my potted bougainvilleas once a week since I’ve found that this strikes the perfect mix between supplying the necessary hydration and encouraging blooming.
Every time you water, give bougainvilleas a good soak until water starts to leak out the pot’s base.
This helps the roots become established in the soil and raises both their resistance to drought and their capacity to obtain nutrients.
Established bougainvilleas that are planted in garden borders frequently don’t need any additional watering and flourish when given careless handling.
Read my post Why is my bougainvillea Dying to Save It if your bougainvillea is not growing.
2. Too Much Fertilizer Encourages Foliage at the Expense of Flowers
Bougainvillea plants can be encouraged to produce an abundance of lush green stems and foliage at the price of flowers by regularly fertilizing the plants.
Because they are resilient plants, bougainvilleas may grow in a range of soils. The most crucial soil quality for promoting flowers is that it drains effectively rather than being excessively fertile.
Bougainvilleas that have been grown successfully in garden soil typically don’t need any additional fertilizer to bloom.
The roots may deplete the potting soil of nutrients if the bougainvillea has been growing in a pot for a number of years, in which case additional fertilizer may be needed for the bougainvillea to flower at its best.
The secret is to just apply an all-purpose NPK (nitrogen, phosphorous, and potassium) fertilizer at half strength in the spring to give the plant the nutrients it needs for growth and flowering without overdosing the soil with nitrogen.
If you don’t get any flowers in the summer, cut back on your bougainvillea fertilization schedule and let the plant go for a year.
Although bougainvilleas can flower in somewhat nutrient-poor soil with a high percentage of sand or perlite and can grow in neglectful conditions, they typically fare best in well-draining loam soil.
The bougainvillea should be in better shape to produce blossoms the next year without further fertilizer.
(View my article on potted bougainvillea growth.)
3. Not Enough Direct Sun Light For Flowering
Native to South America’s tropical regions, bougainvilleas thrive in direct sunlight.
The bougainvillea tends to produce more foliage and fewer blooms if it is placed in the shade.
Locate your bougainvillea in a sunny area with at least 6 hours of direct sunlight for best flowering to ensure a healthy bloom.
This is one of the reasons it is ideal to grow bougainvillea in pots, where you can place them in full sunlight during the spring, summer, and fall and bring them indoors for protection during the winter (USDA hardiness zones 9b and 10).
Interestingly, the length of the day also affects how effectively the bougainvillea flowers, as does the sun’s intensity (full sun is preferred to indirect light).
4. Bougainvillea Flowers Best with Shorter Day Lengths
Due to adaptations to its natural environment in the tropics, where the days are shorter than nights during the dry season, this preference for shorter days for boosting flowering is the result.
In order to encourage your bougainvillea to bloom, it is crucial to mimic the ideal lighting conditions found in its native habitat.
In northern latitudes where the sun can rise and set very early and late, it is common for the length of the day to be excessively long, which prevents flowering (in the UK, the length of the day can reach 16 hours on June 21st, while in New York it peaks at 15 hours). Therefore, to get the most out of your bougainvillea, it may be necessary to:
- Find a spot in your yard that receives afternoon shade, or for serious flower lovers…
- To encourage flowering, cover the plant with a dark cloth in the nights to simulate the shorter days of its original tropical environment.
Although artificial lighting can also prevent flowering, choose a location with direct sun during the day and shaded or even darker evenings where it is not in the glare of house lights at night if your bougainvillea is indoors. If your bougainvillea is indoors, it may be easier to ensure that the Bougainvillea is in less than 12 hours of light.
5. Slow Draining Soils Prevent Blooms
The presence of soggy soils that hold an excessive amount of water is another factor in bougainvilleas’ failure to flower.
Slow-draining soils have the same result as excessive watering. Clay soils and low lying, wet soils prevent the roots from having a chance to dry out between waterings.
Bougainvilleas should be planted in pots or containers in gardens with soggy soil (especially in cold areas).
Compared to garden borders, pots offer better drainage conditions, and it is much simpler to adjust the potting mix to a plant’s preferences.
Use a potting mix of high-quality multipurpose compost and add some horticultural sand, grit, or perlite to increase drainage for healthy bougainvilleas that avoid root rot and bloom to their maximum capacity.
By simulating the dry soil conditions of the bougainvilleas’ native habitat, this well-draining soil mixture guarantees that the plant will have the chance to blossom without being hampered by soggy soil.
(See my article on how to water potted bougainvillea.)
6. Warm Temperatures Increases Blooms
For more blooms, bougainvilleas require warmer temps. Although bougainvillea is versatile and may flower in cooler nighttime temperatures, the ideal temperature for flower development is around 65°F (18°C).
It is recommended to bring the bougainvillea plant indoors or cover it with fleece to prevent blooming if the weather is unseasonably cool or cold throughout the summer.
Planting bougainvilleas in a pot or container to bring the plant indoors in the fall is a good idea because they are not cold hardy and need protection throughout the winter in cold locations.
A warm, bright window is frequently the finest location to grow bougainvilleas and guarantee that they blossom in cooler climes.
(To learn how to rescue a bougainvillea that is losing its leaves, read my post.)
How do I get my potted bougainvillea to bloom?
Make sure the bougainvillea has 12 hours of continuous darkness every night to enhance the number of blossoms on the plant. Because bougainvilleas have short days, they can flower with less light and less darkness. In the summer, water bougainvillea less frequently to induce drought stress, which encourages flowers.
How do I get my bougainvillea to bloom?
Water and fertilize, but not excessively, in the spring and summer to promote flowering. Give a plant some water if it begins to wilt because it is too dry. Instead of using a high-nitrogen fertilizer, choose one with a high potash content, such a hibiscus fertilizer.
How long does it take for bougainvillea to bloom?
A average, healthy bougainvillea will continue in a blooming period for 3 to 5 weeks with at least 5 hours of direct sunlight per day.