Raised bed questions.

Raised bed questions.

This might be a ridiculous question but I haven't found a definetive answer anywhere. I'm building two raised beds in the next couple of weekends and planning to make them both 4'x8' (I really want to avoid clambering/falling into them as I'm kinda clutzy). Our soil sucks, its virgin clay. As in, they plowed 30' off the top of a hill and that's where they built our house. With that in mind, how high(deep?) do the beds need to be assuming we grow cukes, tomatoes, pumpkins, and peppers? I've seen sites saying anywhere from 3" to 2' is good but I'm assuming that depends on a bunch of factors. Hopefully we can get away with 8-12" but I'd rather do whatever it takes the first year and be done. :) Also, what did you build your raised beds out off? Trying to decide between my two ideals of stone/brick walls and a no screw set up with composite boards. We've had termite issues in the past so I'm trying to avoid wood.
Redid my room

Redid my room

Flower Id’s?

Flower Id’s?

The beginnings of my garden

The beginnings of my garden

hi im nick

hi im nick

Mystery Herb

Mystery Herb

Another Mystery Plant

Another Mystery Plant