The best time to plant Gardenias is in spring so they have plenty of time to produce roots before being challenged with winter cold. Gardenias prefer to grow in acidic soils. Use fertilizers and soil amendments that do not contain lime that will ‘sweeten’ soil, or raise the pH.
If growing a Gardenia in a container, add trace minerals including iron. Gardenias dislike root disturbance, so add mulch to root areas rather than cultivating soil around roots.
Night temperatures between 50-55 degrees are necessary to form flower buds.