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.
Barbara Karst bougainvillea with its showy pink bracts is a popular variety grown in gardens across warm climates. However, this tropical beauty can sometimes develop issues with curly, wrinkled, or twisted leaves. If your Barbara Karst bougainvillea’s foliage looks less than perfect, don’t panic. In most cases, leaf curl in bougainvillea is due to environmental factors or pests and is easily corrected with a few care adjustments.
Common Causes of Leaf Curling in Bougainvillea
Here are the most frequent culprits behind curled leaves in Barbara Karst bougainvilleas:
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Insufficient Water Both under and overwatering can cause leaves to curl. Drought stress from dry soil makes leaves curl and wrinkle, while saturated soil leads to root rot and curled foliage.
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Light Imbalance: Too much or too little light leads to leaf curling. Low light causes weak, curled growth. Direct hot sunlight burns and dehydrates leaves, making them curl.
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Temperature Extremes: Chilling winds and cold temperatures cause leaves to shrivel and curl inward. On the flip side, scorching heat also leads to curled, dried leaves.
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Pest Infestations Sap-sucking bugs like aphids mealybugs and mites cause leaves to distort and curl as they feed. Their toxic saliva damages plant tissues.
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Diseases: Fungal and bacterial diseases disrupt nutrient and water movement in plants. Leaf spot, powdery mildew, and root rot especially lead to curly leaves.
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Poor Soil Conditions: Compacted, clay-heavy soil prevents proper root aeration and drainage. This stresses the roots and causes curled leaves.
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Nutrient Deficiencies: Lack of nitrogen, iron, calcium, magnesium, and other essential nutrients lead to stunted, twisted new growth.
Environmental Causes and Fixes
The most common environmental factors that induce leaf curl in Barbara Karst bougainvilleas are improper watering, light imbalance, temperature extremes, and poor soil conditions. Here’s how to identify and address these issues:
Insufficient Water
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Symptoms: Leaves appear wrinkled, dried, or curled inward. Plant may wilt even when soil is moist.
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Solution: Water thoroughly when top 2 inches of soil become dry. Provide 1-2 inches of water per week. Avoid overhead watering.
Excess Water
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Symptoms: Leaves curl downward, turn yellow, wilt, and drop. Roots are dark brown and mushy.
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Solution: Allow soil to dry out between waterings. Improve drainage by amending soil with compost. Repot if needed.
Too Much Light
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Symptoms: Leaves curl upward, look dried out and burnt along edges. Sunscalding on bracts.
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Solution: Move to a partially shaded location. Use sheer curtains to filter harsh sunlight if growing indoors.
Too Little Light
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Symptoms: Weak, sparse foliage growth. Leaves droop and curl downward.
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Solution: Place in a bright, sunny spot indoors or outdoors. Prune overhanging branches blocking sunlight.
Temperature Extremes
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Symptoms: Chilling causes tight, inrolled leaf curl. Scorching heat leads to dried, upward curling.
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Solution: Move potted plants to protected areas. Water frequently during heat waves. Cover or move indoors when temperatures drop.
Poor Drainage
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Symptoms: Lower leaves yellow and curl upward. Roots appear brown and rotten.
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Solution: Repot in a container with drainage holes using well-draining soil. Add organic material like compost to improve aeration.
Pest Problems
Bougainvillea plants are prone to infestations by aphids, mealybugs, scales, spider mites, and caterpillars. These bugs suck sap, damage plant tissues, and introduce diseases that distort and curl leaves. Here’s how to tackle the common pests:
Aphids
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Signs: Clustered colonies of green, gray, black soft-bodied insects on young shoots and undersides of leaves. Curled, sticky leaves.
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Solution: Knock off with strong water jet. Apply insecticidal soap or neem oil sprays every 5-7 days. Introduce ladybugs.
Mealybugs
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Signs: Clusters of tiny white cottony insects in leaf joints and stems. Curled, yellowing leaves with sticky honeydew coating.
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Solution: Dip a cotton swab in alcohol and wipe off insects. Use neem oil or insecticidal soap sprays.
Scales
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Signs: Clusters of small bumps on stems and leaves that look like scabs. Sticky honeydew and sooty mold on leaves.
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Solution: Prune off heavily infested shoots. Use horticultural oil or neem oil sprays every 10-14 days.
Spider Mites
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Signs: Tiny moving dots on underside of leaves. Fine webbing, yellow stippling on leaves. Leaves curl downward.
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Solution: Hose down plants to dislodge mites. Apply sulfur sprays every 5-7 days. Release predatory mites.
Diseases Causing Curled Leaves
Fungal and bacterial diseases disrupt nutrient transport in bougainvillea, leading to distorted, curled foliage. Monitor for these common diseases:
Leaf Spot
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Signs: Small, circular brown lesions on leaves that enlarge over time. Leaves curl, twist, yellow, and drop.
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Solution: Prune and destroy infected leaves. Apply copper fungicide sprays every 7-10 days. Avoid overhead watering.
Root Rot
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Signs: Leaves curl, wilt, and turn yellow. Roots are brown and mushy.
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Solution: Avoid overwatering. Repot in new container with fresh potting mix. Apply fungicide drench.
Powdery Mildew
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Signs: White powdery coating on leaves. Distorted, curled leaves. Stunted growth.
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Solution: Prune infected parts. Apply neem oil or sulfur fungicide sprays every 7-10 days. Avoid overhead watering.
Preventing and Managing Leaf Curl
You can avoid leaf curl in Barbara Karst bougainvilleas by providing proper care and following these tips:
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Water thoroughly only when the top few inches of soil become dry.
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Ensure plants receive at least 6 hours of direct sun daily. Filter intense afternoon sun.
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Prune plants after flowering to remove diseased and pest-infested parts.
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Check for pests like aphids and mealybugs regularly under leaves. Remove by hand or use insecticidal soap sprays.
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Apply a balanced liquid fertilizer every 2-4 weeks during the growing season.
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Repot in a container with drainage holes, using a well-draining potting mix amended with compost.
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Protect plants from temperature swings and chill. Move potted plants to sheltered areas.
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Inspect leaves and stems periodically for disease signs like spots, rust, or mildew. Remove and destroy infected parts.
With proper site selection, routine care, and pest monitoring, you can keep the foliage of your Barbara Karst bougainvillea healthy and lush. Curled leaves are usually a temporary setback easily fixed by tweaking care and treatment. Pay attention to your plant’s needs, and you’ll be rewarded with a vigorous bounty of bracing pink blooms against deep green 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.
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.
Common Bougainvillea Problems
FAQ
How do you treat bougainvillea leaf curl?
Why are my bougainvillea leaves curling up?
Why does my Barbara karst bougainvillea lose its leaves?
There are times when my Barbara Karst Bougainvillea loses its leaves, particularly if it gets too cold. It’s a semi-deciduous plant, which means it can shed its leaves in response to stress, like a drop in temperature or insufficient water. However, once the conditions improve, it usually bounces back with new growth.
Why is my bougainvillea leaf curling?
What causes bougainvillea leaf curl? The main reasons for bougainvillea leaf curl are pests, water stress, diseases, low light intensity, and scorching heat. Flushing the leaves with a jet of water and treating them with neem oil can get rid of pests, but if the issue is insufficient light, move the plant where it will receive full sun every day.
Why are my bougainvillea leaves wrinkling?
Mealybug infestations can also cause leaf damage and wrinkling in bougainvillea. Mealybugs are small, oval sap-sucking insects that infest many different plants, including bougainvillea. They appear as white, cottony masses on the stems and leaves of the plant. Mealybugs can weaken the plant and cause the leaves to curl.
How do you care for Barbara karst bougainvillea?
Barbara Karst Bougainvillea is a fast growing plant and may deplete the nutrients in its soil over time. Replenish them with a gentle organic fertilizer or compost every 1-2 months depending on your location and season. Fertilize more often during the growing season and in warmer and brighter climates.