I've always been puzzled as to whether there's some "basic knowledge" I should have when buying fertilizer (other than taking Chemistry), over and above that they mean Nitrogen, Phosphorus and Potassium. I know N produces green growth, P is important for root and flower development, and K for winter hardiness. And that "numbers" invariably include fillers. But ratiohas been mentioned in these forums several times. Evergreen fertilizer, for example. I've seen 8-6-8, yet others (and I've thrown empties away) also said evergreen yet their formulations didn't maintain the ratio, (i.e. 16-12-16, or 4-3-4). Guess what I'm asking is: what is the optimum ratio for, say, the evergreen family? Is there some general standardized knowledge for ratios...without going back to school?