I have two tropical hibiscus in large pots that I have had for years that are not looking good. I'm hoping someone can help. I think it may be a nutrient deficiency of some sort, but can't figure it out. I live in NY, so overwinter them indoors next to a large a sliding door with lots of light. In years past I have had issues with aphids. This year I thought I would be preemptive and water in some Imidacloprid early right when I brought them in (October), and again in February. I've recently come to realize some folks say that hibiscus don't like systemics. I tested the pH of my water and its right around 7.0. (I have acidic well water so have a neutralizer with calcite / limestone so I don't corrode my copper plumbing piping) I use Peters 20-20-20 water soluble fertilizer. This is not the normal leaf drop you see as the growth progress, where the leaves yellow and drop off. Here, they are remaining green and appear too just be drying up. One portion of the leaf will be crispy while the other portion is still alive, albeit for a while, until the remainder of it dries up. They do have alot of buds on them, some of which are dropping off before blooming. Below is a photo of some of the leaves that are falling off. Any help would be greatly appreciated. I'm stumped on this one and would hate to lose them, especially the one that is a "hand me down" from my Dad.
