I got some plumeria cuttings when I was in Hawaii last May. I live in Kansas and the temperatures here swing drastically. I had to bring them in in early September and put them under grow lights in the basement. They are in their own little closed off section where I keep the temps at 80 deg. during the day and let it fall to 75 deg. at night. They are under LED grow lights with the leaves are recieving 70,000-80,000 lux. All of them are on heating pads with soil temps at a constant 80 degrees. Soil is a 50/50 blend of miracle grow garden soil and volcanic pumice.
However, the space that they are in feels very humid and the soil stays wet for several days.
The leaves begin turning lime green then start developing brown patches before falling off. The rest of the leaves don't look healthy and new growth has stopped. The uppermost leaves look the healthiest. There are some tiny bugs that hang out on the leaves that insecticide/mite killer isn't taking care of. They are wingless critters that I usually see in wet soil but are on the leaves for some reason. I don't see any webbing so I'm assuming they are not spider mites. I've also sprayed fungicide on the leaves but it didn't have any effect on the leaf drop. I'm not sure if they are dropping because of the humidity allowing a disease to spread, bugs, root rot, or what. Thank you for your help!
-Tim