Gardenias can be damaged by cold temperatures. So move potted gardenias inside when temperatures drop below 60 to 65 degrees at night. Consider transferring garden gardenias into pots for the winter if your area experiences freezing nights in the winter. Use a garage or greenhouse to overwinter your gardenias. Do not disturb the plant or its leaves while you're moving it; gardenias do not like to be disturbed or handled. Fertilize your gardenias once a month, even in the winter. Put a layer of fertilizer around the base of the plant.