Could you tell me why all my gardenia buds are turning black?
Why Are All My Gardenia Buds Turning Black
Certified GKH Gardening Expert
This can happen for a few reasons.
1) Did you have a cold snap or light frost? This can leave the leaves and branches looking ok but will kill (and blacken) the more tender flower buds.
2) Pests can do this. Some pests attack and kill the buds on a plant. Pests like thrips or aphids. Treat the plant with a pesticide, if you suspect pests. Examine the base of the buds closely for signs of them. Some are so small, they will just look like specks of dirt at the base of the flower bud.
3) Fungus can so this. If the black seems dusty, than it is likely a fungus. A fungicide should clear it up.