|my otherwise healthy new gardenia bush gets many buds but as they mature a brownish to black fungus appears at the base of the bud and they drop off. I have applied a sestimic spray but it dosn't seem to help.|
|What you describe is called "bud drop." Flower buds abort and drop off just before they open. Common causes include low humidity, overwatering, underwatering, insufficient light and high temperatures (night temperatures between 50 and 55 ? F are necessary for the formation of flower buds). There's not much you can do to stop this process other than to remove the suspect buds from the plant. The good thing is that gardenias develop lots and lots of flower buds and most of them open.
Good luck with your gardenia!