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.
Once you have worked with raised garden beds for any of your gardening whether it is a flower garden, herb garden, or vegetable garden, you may not want to have an in-ground garden again because of how easy they are for cutting, maintaining, and harvesting. Your entire family will enjoy having some garden beds that are raised above the ground including your children.
You will have fewer problems with pests gardening in raised garden beds. If you have had previous problems with burrowing rodents, a lining of chicken wire in the bottom of each will eliminate them. Weed control is much easier handle because you can walk around a raised bed without having to bend over to pull out, if you have any weeds at all.
Then, determine what you would like to use for the anchors. If you built your garden bed out of lumber, you could use nails as anchors, spacing each nail the appropriate distance as determined by the results of the calculation in Step 1 above. If your garden bed is made out of a composite material (part wood waste, part plastic), I recommend using an anchor placed on the outside of the bed. Since my beds are 6 inches high, I used 12 inch metal spikes I bought from the local hardware store, pounding them into the soil directly on the outside of the garden bed.