It could be any number of problems such over watering, planting in the wrong soil (clay versus sand), plant not getting enough of too much light or a virus. I have found taking a branch and a description of where the plant is located at your home to the local nursery can get your close to a remedy.
Your planting site may not be right for the plant. It may have too much water. They need some shade and partly sun to thrive. I have a lovely bush about 6 feet tall and wide now. It grows beautifully beneath a weeping cherry tree, beside a garden pond. It has been in full bloom since january. It could also be located in a site that is too dry for it. You haven't described the site or location, or growing conditions, therefore it is difficult to offer a good answer. Good luck to you.
My gardenia which is now three years old. It is in a large pot in my garden in Spain which has sun and shade (as under and Almond Tree) last year it was beautiful at this time of the year (covered in flowers) but this year the leaves are very yellow and the buds seem to be drying off on the branches before they open. I water the tree on a regular basis by making sure it has enough water, without becoming water logged. I have feed the tree with slow release fertiliser which I have done on previous years, as I was not originally living in Spain (as now) on a permanent basis, and it was a beautiful and healthy looking tree, thus do not know why it looks as it does now as I have done nothing different this year as in previous years.
I recently received a gardenia bonsai plant from my daughter for mother's day and I did everything the instructions said to do. So why r my leaves turning yellow. I have my plant sitting next to my turtle tank for the humidity and its also next to the window where the sun comes in every morning. What am I doing wrong?
