After starting to make our veggie boxes, and cutting them to 5' by 3', I started one of the gardening books that I had laying around. It's called Square Foot Gardening. In it, Mel (the author) claims that he has the answer to all veggie box woes and makes a pretty convincing argument. After the convincing, he tells you to make 4' by 4' boxes with 3 feet between them. He wants them 6 inches tall and filled (by volume, not weight) with 1/3 peat moss, 1/3 vermiculite, and 1/3 blended compost (at least 5 different ingredients or types if you are buying bagged). He also wants you to make a physical grid on them, separating them into one foot square segments.
This changed our game plan slightly, and I am happy with the new look. We now only have four boxes against the house instead of all six, and two are on the other side of the lawn. The little guy and I filled two of them up this morning, and he happily helped me drill with the drill bits and then water the dirt as I got the twine in place for the grid.
In the book, he tells you how many of each veggie can go into one square foot, and says it helps you not waste seeds and to visualize your harvest by breaking it into smaller pieces.
We are excited to get planting!