Hi Anne,

Thanks again for reaching out to the UVM Extension Master Gardener Helpline with your bougainvillea question.

From your pictures, the leaves show:

• Yellowing that starts between the veins and along the edges,

• Tan, papery tissue at the leaf margins, and

• A few small, round “punched-out” tan spots on older leaves.
  
  

Taken together, this pattern is most consistent with leaf-edge scorch and general stress, not a spreading disease or insect problem. Bougainvillea grown indoors in our climate often shows this when:

• The potting mix stays too wet or dries out sharply,

• The roots are chilled near a cold window, and/or

• Leaves get bright sun through glass followed by cooler night temperatures.

The small round spots appear to be old dead tissue that has dried and fallen out, rather than fungal leaf spot (which usually has darker, irregular lesions and a more “speckled” pattern across the leaf).

Recommended steps:

• Repot into a fresh, well-draining mix (good quality potting soil with added perlite or pine bark). Use a pot with drainage holes and avoid one that is much larger than the root ball.

• Remove the worst affected leaves. They won’t recover and trimming them off makes it easier to monitor new growth.

• Adjust watering. Water deeply and then allow the plant to dry out between waterings. A moisture meter can help tell you when the plant needs water... or you can try the simple chopstick test by inserting the chopstick in the soil -- if the chopstick is wet with sticky soil on it, it means the plant is not yet ready for water.

• Move the plant slightly away from the cold window glass to reduce night-time chilling, but keep it in bright light.

• Maintain as even a temperature as possible around the plant.

• Also inspect for spider mites. We noticed some webbing in one of the photos. Here is some additional information on indoor plant pests: https://extension.umn.edu/product-and-houseplant-pests/insects-indoor-plants
  
  

New leaves are the best indicator going forward—if conditions improve, new growth should be greener and free of edge scorch.

References:

• Clemson Cooperative Extension – Bougainvillea: https://hgic.clemson.edu/factsheet/bougainvillea-2/

Mississippi State University Extension – Bougainvillea in containers:https://extension.msstate.edu/news/southern-gardening/2024/bougainvillea-perform-their-best-containers