An old article in Fine Gardening Magazine once said that Chemical fertilizers are like cocaine for plants. Growth is fast but not good for the plant down the road. Natural or organic fertilizer on the other hand is slow and safe and in the long run, the plants prosper much better.
The best way to look at this, over fertilizer with synthetics will kill the plant (just like an O.D.) but not so with organic. If you can use the synthetics in a very weak state, then I guess they are best.
