The blooms are actually coming in! They are wonderful. I also spray for bugs and I'm wondering if it yellows the blooms early. Also, the leaves at the bottom are yellow. Too much water? Last week the plant (in a container in sun half of the day) was drooping, so I watered. We had tremendous rain this winter and now it's heading toward a hot season in California. Do the leaves yellow and die off in spring?
Gardenia Blooms Don’t Last
Certified GKH Gardening Expert
Yellow leaves on gardenias can be caused by several things. This article will help you with that: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/helping-a-gardenia-bush-with-yellow-leaves.htm
The spray should not yellow the blooms early, but whatever is causing the yellow leaves may be doing that.