Square Foot Gardening means that you section off your beds into one-foot squares instead of planting in rows. There are many charts available online that show you at a glance how many plants of each type to plant in each square foot.
Chart of plants and how many to plant per square, explanations on how to calculate and sample pictures on my square foot garden
My square foot garden PDF guide by suwanee.com
ecogreenlove 
Great chart!
Just a note. The only way you can accomplish growing so closely together is by using a SUPER growing medium such as the one developed by Mel Bartholomew, inventor of the Square Foot Gardening method, after decades of research – 1/3 peat moss (or coco coir), 1/3 coarse vermiculite (perlite can be used in a pinch but doesn’t hold water as well and floats to the top) and 1/3 of a GREAT blended compost (containing more than 5 varied ingredients). Homemade compost is best as many ingredients are used.
Unlike bagged soils, this medium will never need to be replaced! After harvesting each square, simply add a trowel of compost in that square, mix and replant.
~ Kim, Certified SFG Instructor
Hi!
Thank you for the feedback, will make sure to add this note to the article 🙂