Yellowing Leaves Falling Off
I have planted three gardenias outside. One has a good number of speckled yellowing leaves, a few of which have fallen to the ground. The other has many brown leave tips that are wrinkled and dry, thoughthe plants are watered every other day. The third one still has green leaves.
Certified GKH Gardening Expert
Here is an article that you may find helpful: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/helping-a-gardenia-bush-with-yellow-leaves.htm