Not a direct answer to your question but something to consider.....
I'd look into a new, dwarf raspberry, BrazelBerries 'Raspberry Shortcake'. Rather than the space and trellising needed for a typical raspberry vine, this is a very productive, self-fruitful berry that is intended for container culture. The berries are very tasty! I purchased one this spring and have decided to expand my collection in the coming season. This is an ideal plant for those renting or on the move or with minimal inground planting space.
The 5-1-1 mix will work fine for either the planter above or the container (s). And fwiw, standard raspberry canes should be planted 2-3' apart, so planting these in your wooden planter would limit that to two plants (3 if you squeeze :-))
Here is a link that might be useful: Raspberry Shortcake
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