Q.Mini Gardenia Bugs
What bug infestation can cause leaves to turn yellow in mini gardenia bushes?
Certified GKH Gardening Expert
There are several, such as aphids, mealybugs and scale, that can do this. These articles will help you with figuring out which one you have:
https://www.gardeningknowhow.com/plant-problems/pests/homemade-aphid-control-a-natural-way-to-kill-aphids.htm
https://www.gardeningknowhow.com/plant-problems/pests/mealybugs-white-residue-on-plants-leaves.htm
https://www.gardeningknowhow.com/plant-problems/pests/scale-bug-how-to-control-plant-scale.htm
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/helping-a-gardenia-bush-with-yellow-leaves.htm