What We Used and Why:
When we first began raised bed gardening, we essentially bought a kit from Home Depot of single plastic rails, about 4" high, with pound-in corner posts. We began with a single and built out to a double. We grew tomatoes, beans, peppers and strawberries (which took over the garden, the yard and the county).
But -- I wanted more.
So, I determined to built raised bed gardens of my own design.
First, I bought 12 4"x6"x8' rails, all of pressure treated lumber for durability.
I skipped the 6"x6" rails, or, the real live railroad ties, because I felt I didn't need the bigger rails, 4x6 was good enough for my needs and I didn't want to be rolling on the ground screeching the "Bohemian Rhapsody" after trying to lift one of the heavy rails into place. (I realize that the width and length of the beds will make it difficult to plant and work the center without tramping the soil down, so as we move forward, I'll either build walkways through the garden or just send Mr. Bitterman in there to do the weeding and harvesting.)
The 4x6 rails were manageable for me, fit nicely together and their weight was enough to hold the structure in place. To ensure no shifting when the dirt and water were added, I bought 3' half inch pieces of rebar and drove them down beside the rails. They held everything in place. (I also use metal straps I found at Home Depot to hold the joints together so they don't go walkabout.)
Building the new garden on the river rock section of the backyard, I figured I already had good drainage. I covered the base with landscape fabric (got a big, expensive roll, not realizing that I already had plenty hidden in a safe place in the garage), held down by extra rocks and bricks in corners.
With the beams in place, it came time to fill the garden. First, I had Home Depot deliver 20 bags of 2-cu foot Miracle Grow Garden Soil. They delivered it with the rails and put it in a neat pile right next to the garden. I hefted each bag over, waddling as I went, singing higher with each chorus of "Bohemian Rhapsody" and poured them into the structure. Below is what I wound up with after 20 bags and two hernia operations.
Nowhere near enough.
Traipsing over to my local Santa Fe Sand and Gravel outlet, I ordered four cubic yards of garden soil. When they delivered it, They could only back the truck in a few feet past the gate as the electric lines overhead would have proven to be quite the nasty surprise while dumping. Suddenly, I had a pile of four cubic yards of soil some twelve feet from the garden. Time for the wheelbarrow and shovel along with another lively chorus of Freddy Mercury's greatest hits.
After a few days of wrestling with the wheelbarrow, a number of elegant curses and a splinter the size of a steak knife in my hand, the new garden (Nora) was filled. As was the old garden (I'm thinking now of calling it Nick), the pumpkin garden and the butterfly garden (Honi), who you have yet to meet.
Running two independent vegetable gardens gives us the chance to grow more veg, rotate crops, experiment with heirlooms and provide Mr. Bitterman with additional dirt clods which he can then chuck at the next door neighbor during his regular fits of pique.
It's exciting to consider the possibilities.
Now, I just want to start growing.