Bougainvillea is an evergreen tropical plant that blooms in spring from beginning in May and continue to bloom until the end of September in warmer climates.
The reason why bougainvillea isn’t blooming is that it is under stress. Bougainvilleas require six hours of direct sunlight and bloom at their peak when the day’s length is less than 12 hours. The soil is too wet to allow bougainvilleas to flower and excessive fertilizer results in the lush foliage to be less flowering.
Read on for more details about the reasons your bougainvillea might not be blooming , and how could you do make sure that you have an impressive display of flowers in the coming season…
1. Too Much Water Prevents Flowering
Bougainvilleas are drought-tolerant plants that actually thrive in dry soils that require frequent irrigation.
The most common mistake made by gardeners is to adopt the same method like hydrangeas, roses, etc. and to ensure that they water regularly to ensure that the soil stays always damp.
If you do not water bougainvilleas often, the plant can become stressed due to this being contrary to the conditions it prefers in its dry and hot native habitat, which results in less blooms.
For bougainvilleas, it is ideal to imagine as having the same requirements for watering as Mediterranean plants like lavender and wait to water until the soil is dry, even to the winter’s depths.
This mimics their natural flowering time (they bloom during summer, which is dry in home country of South America) and the stress from water triggers the development of vibrant blooms (and bracts).
Personally, I water my bougainvilleas in pots each week in the summer and spring and have found this to be the perfect balance to satisfy the requirements for moisture and encourage flowering.
Give bougainvilleas a nice soak every time you water them to the point that water escapes from the bottom in the bottom of your pot.
This helps the roots grow in the soil, which enhances their drought tolerance as well as their ability to absorb nutrients.
Bougainvilleas that have been established, and planted in garden boarders, usually do not need any watering or irrigation, and can flourish and bloom even with poor care.
(If your bougainvillea’s not growing, check out my article on the reasons why my plant declining to help save it).
2. Too Much Fertilizer Encourages Foliage at the Expense of Flowers
Frequently applying fertilizer to bougainvillea plants can stimulate lots of lush green foliage and stems at the expense of flowers.
Bougainvilleas are tough plants that are able to adapt to a range of soil types. The most crucial characteristic of soil to encourage blooms is that the soil drains well instead of being overly fertile.
Established bougainvilleas that are well established and planted in soil of the garden generally don’t require fertilizer to flower.
If, however, the Bougainvillea is being grown in pots for a number of years, the roots could drain the soil in the pot of nutrients. In this the need for additional fertilizer could be needed for Bougainvillea to bloom at its most effectively.
The most important thing is to apply a half strength, all-purpose NPK (Nitrogen Phosphorous as well as Potassium) fertilizer in the spring to supply the plant with the necessary nutrients needed for growth and blooming, without overburdening your soil Nitrogen.
Reduce the frequency of fertilization for bougainvillea if not seeing blooms in the summer and then leave the plant to grow for a whole year.
Bougainvilleas thrive in poor conditions and may bloom in relatively nutrient-dense soils with a large amount of perlite or sand, but prefer well-drained loam soil.
If you do not add fertilizer, the bougainvillea will be in better shape to show flowers.
(Read my article on on how you can cultivate bougainvillea inside pots).
3. Not Enough Direct Sun Light For Flowering
Bougainvilleas originate from the tropical South America where it enjoys the full sun..
If it is planted in shade, the bougainvillea will grow more plants and less flowers.
To ensure the best bloom, place your bougainvillea in a sun-drenched location that has at least 6 hours of sunshine to guarantee an excellent bloom.
This is among the reasons it is recommended to plant bougainvillea in pots that are in full sun throughout the months of Spring, Summer and Autumn and to bring the plant indoors in winter to protect it as it isn’t cold-hardy (USDA hardiness zones 9b, 10).
It is interesting to note that it’s not just the brightness of the sun’s rays that are important in flowering (full sun, not direct sunlight) however the length of the day affects the quality of flowers that bloom in bougainvillea…
4. Bougainvillea Flowers are best when they have shorter Days
While Bougainvilleas love intense sunlight in the daytime They actually bloom best when they have days shorter than 12 hours..
The preference for shorter days to encouraging blooming is a result of adaptations to its natural habitat in the tropics in which the days are shorter than nights in the dry season.
To encourage your plant to bloom, it is essential to mimic the ideal lighting conditions that are typical of its natural surroundings.
In northern latitudes where the sun may rise very early and set late, a frequent issue is a long day length that hinders flowering (New York’s peak is 15 hours of light on the 21st of June, UK has as much as 16 hours of light) therefore, to make the most of your bougainvillea, it might be required to:
- Find a spot in your garden that’s shaded during the afternoon, or for those who are serious about flowers…
- Cover the plant with a black fabric the plant at night to mimic the shorter days of the tropical climate in which it is native to encourage flowering.
If the bougainvillea is in a shaded area then it is easier to make sure that the Bougainvillea is not in more than 12 hours of sunlight, however artificial lighting can hinder the flowering process, so select a spot that is exposed to direct sunlight in the day, but dark evenings that are shaded, or when it isn’t under the direct light of your lighting fixtures in the evening.
5. Slow Draining Soils Prevent Blooms
Another reason why bougainvilleas aren’t blooming is due to boggy soils that hold excessive amounts of water.
Slowly draining soils have the same effect as watering often. In clay soils or low lying boggy soils, the roots don’t have the chance to dry between watering sessions.
In gardens that have soil that is damp (and in colder temperatures) plant bougainvilleas in containers or pots.
Pots are more suited to drainage characteristics than garden boarders. It is much easier to modify the mix of potting soil to meet the preferences for the plants.
To ensure that your bougainvilleas are clear of root rot and bloom to their fullest potential, use the potting mix made of high quality multi-purpose compost. You can also include a bit of horticultural sand, grit , or perlite to aid in drainage.
This well-draining soil mix mimics those conditions of dry soil found in the native bougainvillea range and guarantees that the plant gets the opportunity to blossom without suffering from boggy soil.
(Read my article on on how you can water your bougainvillea pots).
6. Warm Temperatures Increases Blooms
Bougainvilleas like warmer temperature to ensure greater blooms. The ideal temperature for the night should be in the range of 65 degrees (18degC) is ideal for the development of flowers however bougainvillea can bloom in cooler nighttime temperatures.
If the weather is not seasonable cold or cool in Summer it could affect the chances of blooming bougainvillea and the plant should keep indoors or covered by a fleece covering to keep blooms in check.
Bougainvilleas aren’t cold-hardy and need winter security in frigid climates. plant them in pots or containers to bring the plant indoors in the fall.
For colder climates, an open, warm window is usually the ideal spot to plant bougainvilleas. It is also a good idea to ensure that they flower.
(Read my article on ways to help the bougainvillea which has lost the leaf).
- The reason why bougainvillea isn’t blooming could be due to the soil being damp, excessive fertilizer, insufficient sunlight and also because of longer days than 12 hours.
- Bougainvilleas require slightly dry soil and warmer temperatures during the night. 6 hours of direct sunlight and less than 12 hours of daylight to flower.
- Over-use of fertilizers and/or too shade typically can result in a lot of foliage, but at the cost of flowers.
- Don’t water bougainvilleas often or plant them in soil that drains slowly as excessive water can hinder flowering. Plant bougainvilleas in pots to ensure better drainage.