I have a gardenia plant I bought last summer. It was blooming well. I brought it indoors as the weather was getting cold. The leaves started turning yellow and are falling one by one from bottom up. Now some of the top leaves are turning dark brown, drying, and falling. I do not have a humidifier yet and have kept the plant away from direct hot air blowing from the home heating system.
The plant was infested by white flies toward the end of the summer and I had sprayed it with recommended pesticide. I have now purchased a can of SAFER houseplant insect killer (containing pyrethrins) which I have not applied yet. What do you think I should do?