Only for myself; if I plan on being on that site fewer than eight years, I'll use dimensional lumber (2 by 8 etc). If I think I'll be in residence eight or more years I'll use cinder blocks.
Very often the first year or two all I use is a bed raised by double digging and lots or organic additions.
Untreated-unpainted lumber has about a 6-8 year shelf life in garden. Or did for me in NY, VT, ME, NH, IL, OH.
