Q.Problem Gardenias
Live in Maricopa, AZ and have Gardenia plant. This year the buds are forming; however, they develop a brown crust and then fall off the plant without blooming.

This could be due to light issues, watering problems and most likely humidity is too low. If potted and indoors placing the plant on a tray of pebbles and water will help.
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-plant.htm
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/growing-gardenias-indoors.htm
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/fertilizing-gardenias-in-your-garden.htm