We did a raised bed garden this year on the deck, since the home owner didn't want me tearing up the yard. It was smaller than I wanted but got quite a bit out of it considering. All in it was about 12 inches deep (2 2x6s), 6 feet long and 3 feet wide. For drainage I think I had a bit too much with this design. The whole bed was raised about 18 inches off the ground with 4x4 legs. the bottom of the bed had 1x2 rail along the bottom of the bottom board and 1x2 ribs across the bed width ways 1 rib about every 3 inches or so. On top of the ribs was chicken wire, and on top of that I put weed barrier to hold the dirt. We did beans, lettuce, and carrots in it. The carrots went gang busters, the beans were ok and so was the lettuce. I did have to make sure it got watered regularly when it didn't rain to keep the soil moisture up. And with any garden I found my self needing to weed it every so often. This wasn't too bad because it's raised so it's easier on your back.