During my 1st winter caring for them, all of a sudden leaves started dropping. So, I had to ask the question: why are my bougainvillea leaves turning yellow and falling off?
Let’s be honest here, bougainvillea is not a plant I grew up with in the Connecticut countryside. I thought it was some kind of exotic plant until I moved to Santa Barbara 16 years ago where it’s found growing in some form or color on every block.
Bougainvillea is ubiquitous in warm climates I tell you. Yet in my opinion, it’s a beautiful “weed”. I had no experience growing bougainvillea until a bought a house 16 years ago with 3 of them on the property.
Turns out, this is one of the most common questions asked about bougainvillea. I’m sharing what I’ve learned (so far!) about this plant that can be used in many ways and gets covered with masses of beautiful flowers.
Note: This post was originally published on 3/16/2016. It was updated on 10/20/2022 to give more information.
Table of Contents
Problems With Bougainvillea Leaves
Looking for bougainvillea care tips? Check out some of our guides: Bougainvillea Care and Growing Tips, How to Plant Bougainvillea in Pots, Bougainvillea Care In Pots, Bougainvillea Pruning Tips, Bougainvillea Winter Care, Bougainvillea Plant Care, & Answering Your Question About Bougainvillea.
I’ve grown bougainvillea in 2 different climate zones. I lived in Santa Barbara, CA for 10 years and have currently lived in Tucson for 6 years. By the way, everything I’m sharing here can happen to bougainvilleas growing as container plants too.
Bougainvillea Hardiness Zone: 9b-11
Santa Barbara USDA Zone: 10a, 10b
Tucson USDA Zone: 9a, 9b
What Causes Bougainvillea Leaves To Turn Yellow
One of the common issues you may have with your bougainvillea is the leaves turning yellow. I can’t tell you why it’s happening to yours, but I can give you some causes and you can go from there.
Too much water. Whatever your soil type, a bougainvillea plant must have good drainage. Too much water can produce an excess of green growth and less flowering. If not caught, overwatering can lead to root rot. If the soil is too heavy, one symptom is that the leaves will curl.
Too little water. During periods of drought (like here in the Western US) bougainvillea leaves will turn yellow and fall off. If you’re not watering your bougie deep enough, this will happen also.
Pests. An infestation can cause it. You might see the leaves (both yellow and green) curling as well.
Fungal disease. They can be prone to fungal diseases (it’s not common) but I’m not well versed on this subject. Mine has never gotten any.
Nutrient deficiency. I never have fertilized any of my bougainvilleas, even those in pots because they haven’t needed it. Yellow leaves on plants can be a sign of a nitrogen deficiency.
Temperature change. This is the reason some of my bougainvillea leaves would turn yellow and fall off both in SB and Tucson. Some would fall off yellow, and some green. When the evening temps dip below 45-50F, it happens.
What Causes Bougainvillea Leaves To Fall Off
My initial experience with the Bougainvillea leaf color change and drop issue had me scratching my head. What was I not doing? Or, was I doing something I shouldn’t be?
I did some reading and got some answers but the final confirmation of the cause came when I visited San Marcos Growers that February to pick up some plants for a client in the San Francisco Bay Area. They’re a large wholesale plant grower with an excellent reputation so, with ears open wide, I listened closely to what they had to say.
Here’s the scoop: Bougainvillea plants are tropical plants native to coastal areas. They do great in Santa Barbara where the winter temperatures rarely dip below the low 40s but the tropics it is not.
One of the causes for those heart-shaped leaves turning yellow (and yes, they turn completely yellow) is environmental. Those cold temperatures in the winter months will do it.
Once leaves turn yellow, then they’ll fall off. As I said above, green leaves will drop also. Some will hang on and then fall off in late winter/early spring when the new growth appears.
In both Santa Barbara and Tucson bougainvillea is semi-deciduous. Not all the leaves fall off but maybe 1/2 of them. Tucson has colder evening temps and I had one of my bougies hit fairly hard but the leaves hit by the freeze turned dark brown and hung on. You can see more on this below.
Water stress in general can cause this. Another reason why yellow leaves fall off of Bougainvilleas in winter is due to a prolonged dry spell. The last few winters haven’t been too cold but they have been dry. The lack of rainfall in the last 5 or 6 winters has brought on drought conditions so the bougies just aren’t getting the water they were used to.
Conversely, leaves can fall off bougainvilleas in the case of too much water. Established bougies prefer infrequent but deep waterings.
Transplant shock. If they’re happy, bougainvilleas are tough cookies and grow like crazy. Despite this fact, their root systems are very sensitive. I’ve never attempted to transplant a bougainvillea and it can be tricky business if you try it. When I plant bougainvillea, I always plant them in their grow pots. This is another tip I learned from another grower back way back when.
Bougainvillea Leaves With Holes
My experiences with holes in bougainvillea leaves have been related to insects. Rather than go into this subject at length here, you can read more about it below.
Find out what’s causing Holes in Your Bougainvillea Leaves.
Do All Bougainvilleas Drop Leaves?
It’s interesting because I’ve noticed that some Bougainvilleas drop more leaves than others. And, there are many different types of bougainvilleas not to mention bougainvillea varieties!
I’ve been told that some varieties tend to shed more than others do although I haven’t delved too far into that topic. However, I’ve observed that Bougainvilleas in cooler, shadier, windier, etc parts of town shed more leaves than those in more sheltered areas with direct sunlight.
There’s a huge hill behind my house that looks out over the ocean, blowing those cool winds. When I was taking a late winter walk up there, I noticed that a 2 block long hedge of bougainvilleas (I believe they were B. San Diego Red) had almost completely defoliated. But, once the weather warmed, they all started to leaf out like crazy.
Best Time To Prune Bougainvillea
I’ve done many posts on bougainvillea pruning so I not going too in-depth on the subject here. I’m including this short blurb on pruning because I’ve found that a great time to do it is when a lot of the leaves have fallen off and before all the new leaves have opened up. You can better see the structure of the plant prior without the dense foliage.
I always wait until the colder months have passed and the nighttime temperatures have warmed to over 45F to prune. In Santa Babara, it was mid to late winter, and in Tucson late winter to early spring.
The pruning that I do at this time is the one that sets the framework shape and size-wise as to how the bougainvilleas will grow for the rest of the season. I find it easiest to do this before the leaves come out and all the foliage is in the way. And remember bougainvillea, blooms on new wood so pruning will encourage flowering.
My B. glabra, which you’ll see a couple of photos up and in the video below, was a flowering machine. It puts out a big show of magenta/purplish color off and on during the growing season which is 9 months out of the year. It grew up and over my garage which sits at the end of a long, narrow driveway. It got a major “WOW” from anyone who saw it. That plant was an adventure in pruning!
By the way, this is How I Prune and Trim my Bougainvillea to Get Maximum Bloom. For more on pruning, check out Bougainvillea Pruning 101.
See how my bougainvillea glabra looks in winter:
What To Do
It depends on what’s causing them to fall off. I’ve touched on that above.
The cause with my bougainvilleas both in Santa Barbara and Tucson was environmental. It happens in late fall/winter. The reason is the colder evening temps. and prolonged dry spells.
So, for this reason, there are two things you can do about those leaves falling off bougainvilleas: #1 is to just let them be and fall where they may, and #2 is to rake or sweep them up.
It’s part of the plant’s natural cycle, and because we don’t get any colorful foliage displays in these parts, we’ll take it as our version of fall!
FAQs About Bougainvillea Leaves
In my experience growing them in two different climate zones, yes. They lose a good portion of their leaves. In Tropical climates, I’ve heard they stay more evergreen.
Common causes that I know of are: not enough water, not getting enough light, or some type of pest.
I can’t give you a definitive answer on this one. I refer to the ASPCA website for this info, and they don’t list bougainvillea. People can have bad reactions to the thorns skin-wise, but in terms of the leaves and papery bracts of the flowers, it’s best to deter your pets (and young children) from eating them.
There are a few reasons. It could be too much or too little water, transplant shock, pest infestation, not enough light, or a temperature drop.
In my experience, it’s their natural cycle of shedding in late fall/winter so they can put out fresh new growth.
The colored parts of the bougainvillea aren’t flowers. They are leaves. The technical term is bract. The flowers are the tiny white centers.
They lose their flowers after every bloom cycle, which is 2-3 times a year. They also lose them in colder temps, when the light levels are too low, or if they’re too much or not enough water.
After the leaves drop and the new growth is well on its way, then those bougainvillea blooms appear. These gorgeous plants are somewhat of a mess, but well worth it in my opinion!
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Nell, the founder of Joy Us garden, was born into a gardening family and grew up in Connecticut’s countryside. After living in Boston, New York, San Francisco, & Santa Barbara, she now calls the Arizona desert home. She studied horticulture & garden design, working in the field all her life. Nell is a gardener, designer, blogger, Youtube creator, & author. She’s been gardening for a very long time & wants to share what she’s learned with you.