Re: Building Raised Beds- How To Questions
Don’t use pressure treated as this can be toxic to both humans and plants. The best alternative in your area, would be either Osage orange or Black locust which can be found at a local saw mill and will last an extremely long time in contact with soil (50years+). Dimensional framing lumber (spruce, pine or fir) from the big box stores will only last a few years, but is readily available and inexpensive.
Cornell has a fact sheet on raised beds here: http://www.hort.cornell.edu/gardening/factsheets/vegetables/raisedbeds.pdf
And Clemson has one here: