It has been my experience that the fertilizer always be added after planting. If planting seeds, the fertilizer, when mixed into the soil and combined with water, will burn the seed. The same is true when planting a potted plant, the fertilizer burns the roots. The soil acts as a filter for the fertilizer and water to sift through. Mixing a fertilizer with water and then applying to the soil won't hurt seedlings, but will hurt exposed foliage unless it is immediately rinsed off, otherwise it will burn.

Garaj,
You have read my 2004 experiment.
My 2005 experiment had a 2 inch stripe of 6 10 6 fertilizer on the surface under the cover. The container never got any top water since we were in our dry season. The Prudens Purple was a beautiful 6 ft. plant, loaded with blossoms but none of them set. The Lithuanian wasn't as pretty a plant but only got 5 fruit.
The Prudens in the soil right next to the cotainer produced 47 fruit and the Lithuanian 55 fruit and the greatest was 85 fruit from Sudduth Brandywine.
I seem to be getting more fruit from my soil each year since I started mulching with grass clippings.
I did everything the same as last year except the fertilizer stripe and no soluble Miracle Grow. If you have any further questions I'll e mail my phone number.
Fred