Hi Sam..

I use a mix for 'wicking' beds.
The basic mix I use is peat, pine bark fines and perlite... in a 3-2-1 ratio

The mix can wick up to a foot. I try to keep my troughs with about an inch of water in them.

I do add to the top third of each bag, lime, Epson salts, and organic ferts. before planting.
I top feed as the plant grows. Heavy feeders, like tomatoes, peppers and eggplants get more.

To keep the roots from becoming root bound...I use containers with holes in the sides.