Raised Garden Bed Drainage System - When vegetables that are growing in raised garden beds using the Square Foot Gardening method, your beds will have to be sectioned off into one-foot sections called planting squares. A 4x4 foot garden bed, for instance, 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. Each planting square comes with an address used to identify the square.
While the options for addressing change, one of the most straightforward would be to use letters for columns and numbers for rows, as well as the mix of the two identifies the square. Numbering beginnings in the upper left corner and goes left to right, top to bottom. I've yet to locate a garden bed that is commercially available with an included feature for marking planting squares off.
I wish somebody would build a Square Foot Gardening grid which you can add into a garden bed that is raised to mark off squares, but until that is available, if you'd like to make use of the Square Foot Gardening process, for marking off squares, you'll need to formulate your own personal system. The first step is to compute the measurements on the inside of the garden bed, which will be the length and width that is actually useable for planting.
The 4x8 foot garden beds I bought, for example, are 4x8 feet from end to end. But when you join the planks in the corners, you lose a number of inches, or so the interior measurements of the garden bed are actually a few inches short of the advertised size. In my instance, my beds have an interior measurement of 46.25 inches x 94 inches. I refer to these measurements as Useable Span for the balance of the informative article.