BUILDING YOUR GARDEN
Once you have your four corner stakes in, be sure to measure corner to corner in both directions - essentially your tape measure is making an "x" in the garden. If the number is the same, then your outside edges are parallel. This is very important when implementing a square foot garden as it is a grid system. Next you will put a string line - at least a foot above the ground along our outside edges from stake to stake. You want the string high so that you can work with your shovel under it without disturbing it.
Take an edger or a square shovel and go STRAIGHT down under the string line. Stand outside the garden so that when you scoop up the shovel of soil - it is on the garden side you are removing the sod.
Removing the Sod.
Once you have your edge line dug out, you can start to remove the sod within the garden. Take your flat shovel and use it on a 45 degree angle to cut down past the sod root zone. Once your shovel has gone past it - about 4" down, you can level off the shovel so you are now shoveling a pancake of sod. The reason to change the angle is that you do not want to be removing more soil than needed, you just want to be removing the root zone of the sod. Be sure to always be working backwards, as in the picture. There is less resistance to remove sod that is already loose from the previous piece being taken. Flip sod pieces on their side in the garden beside your work space, so at the end you will have a line of flipped sod.
Removing the Soil from Flipped Sod.
So now you will be going along the length of your edge again to pick up the pieces of flipped sod and remove any excess soil on them. This process will keep more soil in your garden, as well as make the sod pile lighter that will need to be removed.
If you are adding your sod pile to a compost heap, layer it with different materials throughout - leaves, straw etc. to allow for more aeration and different breakdown times.
Clean up Your Edge.
Now you will need to go back and clean up your edge. A very simple step, but it will make sure that no soil clumps have stayed on the sod you want to keep which would kill the grass. As well it will redefine your edge. The deeper the edge the better because if there is no soil for the grass to grow into - it will not grow into your garden. As well, the deeper the edge, when the lawn mower goes by it can overhang the edge without picking up soil, and alleviate any need for whippersnipping.
The Final Step!
Congratulations! You are almost done. The final step is to take a hard rake and create a nice slope that will go from your deepest edge to the desired height of the soil in your garden. The more defined your garden edges, the less likely your lawn will creep in, the more obvious weeds will be and the more distinct your garden shape will become. The tidier you keep the garden in the beginning will make maintaining it easier throughout the season. Happy Eating!