I live in central-east Georgia. At the beginning of last winter, I noticed the ends of the leaves on gardenia were curling up, like something might be attacking it. As of spring, green upper leaves are still curled, new growth leaves are also starting to curl. Checked for insects and found none. Could it have something to do with low humidity?
Leaf Curl on Gardenia
Certified GKH Gardening Expert
Both white flies and thrips can cause leaf curl on gardenias. Here are some articles that you may find helpful: https://www.gardeningknowhow.com/plant-problems/pests/insects/controlling-thrips.htm