Miraclegrow, New limb growth overdrive, Grow lights

Hi. I live in Missouri, so heading into late Fall/early Winter, but I have grow lights bought from Amazon, so tree's metabolism shouldn't be slowed during Winter sun. My question is if using Miraclegrow, because, I think I remember seeing the ratio at 8-6-8, some numbers that make me think the tree is going to grow in overdrive manor, with a Nitrogen number like that.
I do want overdrive growth for the new limb that appeared on the main stem--right now, the Limb looks tiny, and I have placed training wire to get the Limb to grow upwards, not towards back of tree. With the grow light providing a sunlike day, can I substitute the Bonsai Pro I use in favor of a rich Miraclegrow? Can I use Miraclegrow without diluting it, because of Winter? If I need to dilute it, should I stay with Bonsai Pro--the tree looks healthy.     

The amount of awailable light is the driver for growth, not fertilizer. It is basically just vitamines for the trees making up less than 5% of the dry weight of the leafs. Sinze they are 90% water, the number for a fresh leaf is 0,5%.

Trees uptake can be limited by lack of one substance. But as long as everything is awailable, the tree takes what it needs and the rest is flushed out or bound to the substrate and used later. What product used is not that critical. They all contain every nutrients the tree needs.

Fertilze according to tree growth. The more the tree grows, the more you fertilize, not the other way around.