Posted: 12/03/2014 at 19:53
Dear melanie, wood has a tendency to rot when it is outside, so I made my raised beds from 'pressure treated timber' this is unplaned timber suitable for using out of doors. I used 6 or 7inch wide planks (these are called gravel boards) with 2"x2" posts at the corners. So you hammer the posts into the ground, 4 inches or so, then you drill and screw the gravel board into the little post.
If you want the raised beds to be higher then simply attach another layer of gravel board, but please be aware that it will take an awful lot of compost/topsoil/well rotted manure to fill such a high bed.