They also cycle in and out of bloom with the seasons. Gardenia blooms are sensitive to getting sprayed with anything, including water. Also, try not to touch the blooms. That can cause browning too. This is usually from either too little humidity or water that is too alkaline.
Distilled water is best.
Even though wilting is usually associated with a plant being too dry, it can be a symptom of several different problems. Check to see if the plant is being kept too wet. Exposure to sudden cold temperatures will do it too. Gardenias are sensitive to water with too much lime, like much of the tap and well water in our area. Use distilled water and an acid fertilizer.