I have 3 gardenia bushes planted outside. Some of their leaves are blackish and some are even dead. Is this caused by insects? What should I do?
Gardenia Bushes Outside
Certified GKH Gardening Expert
Your Gardenia has Sooty mold, which is generally caused by aphids or scale.
Neem Oil is a good organic treatment and is safe for people, pets and Bees!
Here are some articles that will help you.