Established outdoor Gardenia massive leaf yellowing and drop?
I have a 4 year old "Chuck Hayes" variety of Gardenia. It has done extremely well with only occasional common Gardenia issues which I corrected promptly. For 4 years(since purchased) the Gardenia has been planted on south facing side of house in ground. Plenty of sun and air movement. It is surround by the driveway, concrete walkway and house. The Gardenia is roughly 4x4. This year the Gardenia grew at least a third in size. For the first time the branches were hanging over all sides of bed. I pruned twice in season to help maintain shape and access to my front door and driveway. Due to water damage my front door has been inaccessable for over a month. In the past week I noticed that more than half of the lower portion of leaves on the entire bush are yellowing with massive amounts falling off. This is first time this has happened. Have had small amounts yellow and fall in past but knew it was just old leaves. This is different. The last time I tended to the plant was exactly one month ago and it was perfectly healthy. No disease, no aphids, no whiteflys, no overwatering, no underwatering, no fertilizing, and I dont believe its an iron def. because the newest growth is still dark green. It was last fertilized in mid summer. The only thing I think it might be is the concrete surrounding it. But don't think that would cause such a dramatic leaf yellow and drop in less than a month. I did recently (August 20th) bust up the bricks that created a step on top of the concrete leading into my house. Could the brick and mortar dusk/particles added too much lime to Gardenia which is only 3 feet away? Lastly I had a pest control service for the first time spray and throw some sort of granule in late August. Any thoughts, comments, suggestions will be most helpful. I am truly stumped and would be devasted if I lost this Gardenia.