In the right conditions, Bougainvillea is a hardy and spirited plant that you’d think could withstand almost any trial and sorrow.
Yet, it does have its weaknesses and can show little will to fight to survive under certain circumstances.
One example is Bougainvillea dropping flowers.
Let’s find out what causes flower drop in Bougainvillea plants and what you can do about it!
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Why Is My Bougainvillea dropping flowers?
The primary reason your Bougainvillea is dropping flowers is exposure to low temperatures. Other reasons are over- or under-watering, insufficient sunlight, and applying the wrong kind – or wrong quantities – of fertilizer. Ethylene gas can also cause Bougainvillea to drop its flowers.
4 Reasons Bougainvillea is Dropping Flowers
1. Change in Environment
Bougainvillea gets “trained” from seedling onward. So, if your plant spent its first few months or years in a hot, humid environment such as a greenhouse, it won’t be a happy camper when you move it somewhere cooler or drier.
To grow Bougainvillea, the secret mantra is “adequate irrigation, warm temperatures, and direct sunlight.” Fulfill these three conditions, and your plant should thrive.
Even if you have been careful to select Bougainvillea based on its USDA hardiness and you live in a Bougainvillea recommended hardiness zone of 9 and above, young plants coming into an area 9 region might still get stressed because of their earlier training.
It is possible to retrain Bougainvillea, so don’t give up on the plant if you find it is losing its flowers in the first couple of blooming seasons after being newly planted.
Bougainvillea typically lives for several decades, so there’s plenty of time to get the plant sorted out, and when you have fixed the problem, I suspect you will feel a tremendous surge of pride and accomplishment.
If the temperature where you live routinely drops below 70°F, transfer the Bougainvillea into a pot and move it indoors during cold spells.
There are specific practices for looking after Bougainvillea in pots, and you should familiarise yourself with them by searching online. Take a look at this practical resource to help you.
To deal with a change of soil wetness, adopt the following irrigation practice to get your Bougainvillea going in its new location. Water the plant until its soil is thoroughly soaked, but then let it dry out again before the next soaking.
What you are doing here is aping Bougainvillea’s historical home in the tropics; heavy rainfall followed by days of dry conditions.
This is what the plant wants and needs at its very core, and eventually, you will be rewarded for your efforts with fantastic blooms all through the blooming season.
Finally, encourage new growth by trimming the plant. For a smaller plant, prune it by up to 50%.
Aim to trim about 20% or 30% for a larger plant. After pruning to encourage growth, give the plant food using a general-purpose 20-10-20 NPK fertilizer.
You mustn’t deviate from the manufacturer’s instructions for using the fertilizer. As we’ll see below, the incorrect use of fertilizer causes many problems for your plant and could even kill it.
2. Bougainvillea Likes Light
You might not have been paying much attention to the light conditions where you bought your Bougainvillea, but if you are experiencing dropping flowers and the nursery you bought your plant from isn’t too far away, you might try this trick.
Return to the store and check out how much light your Bougainvillea received with a light meter. (Talk to a staff member to help you get an accurate reading.)
Return home and compare the amount of light the plant is getting now to the amount of light it was getting back at the nursery.
If the plant now receives less sunlight than before, voila! You’ve found the culprit.
To remedy the situation, equal or better the light level at the nursery, and your Bougainvillea should recover and soon be as right as rain.
3. Fertilizing Bougainvillea can be Tricky
It can be challenging to fertilize Bougainvillea because a lot of nitrogen is excellent for its leaves but terrible for its flowers, and besides, a nitrogen-rich plant is a magnet for pests.
So, what to do?
Knowing when, how much, and what type of fertilizer is too broad a subject for me to discuss here and do the topic justice, so I’m going to point you, yet again, to your local nursery or university botany department.
If you are a passionate gardener or on your way to becoming one, you could also attend flower shows, and soon enough, you’ll be neck-deep in and surrounded by knowledgeable folks with literally decades of experience, most of whom you’ll find are not just willing, but genuinely anxious to help.
4. The Issue of Ethylene Gas and Bougainvillea
A very particular issue – and for me, totally unexpected – is that Bougainvillea is highly sensitive to ethylene gas.
If you think like me, “So what, I don’t have ethylene in my yard,” think again. Turns out, seemingly innocent things like chlorine in the pool, barbecue pits, and ripe fruits all produce ethylene.
As shocking as it might seem, if you have discounted other sources of trouble to make your Bougainvillea drop its flowers, you will have to investigate this possibility.
If your Bougainvillea is near a swimming pool, fruiting plants, or barbecue pit, you must move it.
A Quick Tip: You don’t have to settle for just one flush of blooms in a single growing season.
If you are an advanced gardener (or feel confident enough to try this technique), use deadheading to encourage your Bougainvillea to produce further blooms.
Afterword: Bougainvillea Dropping Flowers
As a decorative plant, even though its colorful bracts are a thing of beauty and joy themselves, it hardly serves its aesthetic purpose if your Bougainvillea remains flowerless.
Fortunately, Bougainvillea is a long-lived plant in the right conditions, and with patience, it is pretty easy to get the plant to produce a bounty of flowers again.
Read about Heather Plant Care next.
Frequently Asked Questions about Bougainvillea Dropping Flowers
How long should my Bougainvillea be in bloom?
In the best conditions, meaning plenty of sunlight (at least five hours of direct sunlight each day if not more), optimal temperature (70°F to 85°F), and adequate irrigation, you should be able to get a minimum of three weeks of bloom from your plant and up to five weeks.
What fertilizer type should I use to help my Bougainvillea flower?
The best type of fertilizer is a slow-release, balanced fertilizer with 10-10-10 or 5-5-5 ratios to ensure an abundance of blooms and safeguard the plant’s general health. But, when encouraging the plant to grow after pruning it, use a general-purpose fertilizer with a 20-10-20 ratio.
Conclusion for Bougainvillea Dropping Flowers
Bougainvillea is dropping flowers for the following reasons:
- Low temperatures
- Over- and underwatering
- Insufficient sunlight
- Wrong fertilization
- Ethylene gas
Daniel has been a plant enthusiast for over 20 years. He owns hundreds of houseplants and prepares for the chili growing seasons yearly with great anticipation. His favorite plants are plant species in the Araceae family, such as Monstera, Philodendron, and Anthurium. He also loves gardening and is growing hot peppers, tomatoes, and many more vegetables.