Another question you must ask yourself is how are you going to weed the garden, as this can take a lot of time. Our answer to weeds is black plastic, as we believe this type of garden is the easiest to maintain, water and harvest. Black plastic normally comes in 10'x25' rolls, which is ideal for our size garden. The 10' width of the plastic allows a foot of space on each side of the garden (the garden is 11 1/2' wide) where we place the fence and plant flowers. Weeding this small area takes almost no time at all and allows us a small 'open' area at the garden edges. For a 46' long garden you need exactly 2 rolls of plastic, which costs only a few dollars, and you waste nothing.
This black plastic prevents weeds and retains moisture
We use the cheap 3 mil black plastic as it seems to last the entire season and is very easy to cut when you have to put a seed or plant thru it. To plant a transplant, we cut an 'X' in the plastic, dig a small hole with our trowel, and place the transplant in the hole.
To plant something like peas or carrots, we cut slits in the plastic, dig out a small trough, and place the seed in the trough, covering them when finished. The seedlings then poke thru the slit in the plastic.
To prevent the plastic from blowing away we use wooden walkways made from treated decking planks and 10' plastic pipes filled with sand and capped off with plastic end caps. The spring winds in our area may become so strong that it will lift the plastic off of the garden, so we also use rocks and boulders to keep the plastic down.