our limitations will go as far as your imagination takes you and the area of space you have to work the garden. There are raised garden bed kits available for purchase at some nurseries, home and garden centers, or on-line.
A 4x4 foot garden bed, for example, will have 16 planting squares (because there are 16 square feet in a 4x4 bed). A 4x8 foot garden bed will have 32 planting squares.
The close plant spacing and the use of compost generally result in higher yields with raised beds in comparison to conventional row gardening. Waist-high raised beds enable the elderly and physically disabled to grow vegetables without having to bend over to tend them.
I wish somebody would build a Square Foot Gardening grid that you can insert into a raised garden bed to mark off squares, but until this is available, if you want to use the Square Foot Gardening method, you will need to devise your own method for marking off squares.