Answer: I haven't seen Rapid Grow fertilizer in years. I think it was manufactured by Chevron and they've gone on to other products. Burning bush should be pruned in spring and you can prune it back by about one-third without causing harm. I wouldn't prune them back to nearly ground level - it would be too much of a shock to the root system to lose that many leaves (they need leaves for photosynthesis).
Best wishes with your garden.
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