Hibiscus fertilizer for post-prune re-foliation
I'm just learning about fertilizers. Previously, I just went to the nursery and used whatever they sold me.
My hibiscus was seriously overgrown, so I gave it a serious pruning. I have my doubts: I may have over-pruned. I'd like to fertilize it to encourage foliage this spring. So my first question is: how long after a serious prune, should one wait before fertilizing?
When I first moved in, it had a whitefly & city mold infestation. I went down to my local nursery and asked for help, and they sold me a 3-in-1 Rose Care treatment which helped a TON. Posts here suggest a 2-1-2 fertilizer for foliage, and that phosphorous (P) in general builds up and becomes harmful to hibiscus. I went through my fertilizer inventory, and nothing I have is 2-1-2, most of my fertilizers are high in phosphorous (P), so I figure I'll need to go back down to that local nursery and ask them for a 2-1-2 to feed my hibiscus. My fertilizer inventory turned up that the 3-in-1 Rose Care treatment has:
6% Nitrogen (N)
9% Available Phosphate (P2O5)
6% Soluble Potash (K2O)
2% Sulfur (S)
So, um, my second question is: have I been feeding my hibiscus a toxic 6-9-6 fertilizer these whole five years?