u/Doomscrye

My potted pixie pink bougainvilleas have leaves that are turning yellow with little white spots and falling off.

I'm pretty sure I'm not overwatering them - they're in a mix of potting soil/cactus soil/perlite/clay pebbles which I've found to drain very well, and I water them only when the soil is dry based on the "stick a finger in it" metric.

I thought it might be a fungal infection, so I gave them a good spray of copper fungicide a few days ago, but the situation is ongoing.

Since I'm in climate zone 4, I suspect maybe they're just not getting enough sun now, although I have a sun lamp on them (which I just moved closer), and are doing the deciduous thing for the winter. That window is facing south, also.

I'd really appreciate your input.