The raised bed we had in Florida was set up with regular treated landscaping timbers, stacked 3 high, 4'x8'. It was a pain nailing each tier together and each corner with each level. Also, the idea of using treated wood in my garden makes me a little uneasy, so I avoid treated woods and unsafe chemicals in my garden.
So this year, especially since we moved, I wanted to use a more simple system. I've been reading about small space, potentially portable (in case we move). and square foot gardening and pretty much set up my systems like that in the past, but there's a lot more involved with it. As with anything, I take the information that works and applies to me, and toss the rest in the wind. So here's what I've got so far. I agree with the 4' width recommended so that you can't walk on soil, as well as making it easier to get in the garden to harvest- proof in the fact by remembering that year I spent the night before my b'day in the ER because I was trying to reach something in my bed that I couldn't reach (and spent three weeks in pain, attending a couple days of classes in a narcotic haze- just to be able to sit upright).
Supplies for 1 4'x4' raised garden bed:
~2 2x8x8's each cut in half to make a perfect square.
~Box of 3" wood screws (you'll need 12 total + a few extra if you strip)
~1 roll landscaping fabric (bought mine at Fred's for $4 per roll, the exact same thing was $16 at the hardware store)
~Staple gun and staples
~Enough fill dirt of your choosing
~Plants- I use veggies, I tend to kill flowers and quite frankly, being able to eat what I grow makes it much more fulfilling than looking at pretty flowers I'm probably allergic to and will kill. And I even tried inter-planting some marigolds and other flowers one year, but they died.
Step 1. Lay out the boards in the arrangement you're going to use. And you'll probably need a helper:
Step 2. I used a basic Black and Decker drill, fully charged up, with a 5/32 bit (general purpose) for drilling the holes in the frame.
Step 3: I secured each corner with one screw around each side to make the basic frame. This was a little annoying switching from the drill bit to the screw bit, but I wanted to make sure the frame was actually a square. It probably would have been easier some other way, but whatever, this worked for me.
Step 4. After securing each side with one screw, I then went around and drilled the holes for the next screws. Drilling the holes after securing each side.
Step 5: Installing the bottom of your box or using a black landscape fabric (this was the easiest part).
Basically, the reason I used this instead of plywood recommended by the SFG'ers is because the plywood was pricey and I will be in this place for at least the season, so I shouldn't have to move the entire garden bed. The beauty of using this is to prevent grass, weeds and other crap from coming up from your dirt and out of the garden bed, more info here. It's even used for creeping veggies to keep the bugs from crawling up and eating your precious harvest from my facebook friend that is a master at straw bale gardening here:
I laid the fabric down, then stapled each corner into place, so that it was taut in place. The rolls were only 3 feet wide, so I had to layer/stagger them to have a solid bottom. Pulling corners, stapling down and then filling in the spaces at about 4-6 inch intervals. Again, I'm not specific, just wanted it to look good.
Step 6. After all the fabric was stapled down, I trimmed the sides up to the edges so they wouldn't be visible once in place.
I'll update with more pictures once the bed is all filled up. We've got lots of goodies going on this year, many things I haven't tried before, so lots of experimenting going to happen while gardening.