Check out this website for more information. http://www.rodsgarden.50megs.com/improvingsoil.htm
Great in depth article on the importance of soil! For those doing raised beds, or container pots, here is another great solution, and or even for those just getting bad "dirt" plots starting to work in ones favor as a more immediate soil. I used to do square foot gardening but my garden is rather large for it these days. However when my kids are grown up and I lose my physical ability to do much more than container pots I'll likely go back to the below method. Mel's mix is best if you do each organically (your own compost, own chicken/cow/worm/mushroom compost, etc.. however not realistic for most) but if you can not, just avoid anything with additives such as Miracle Grow products often times using synthetic fertilizers that over time will not be good to consume nor produce healthy plants.
https://squarefootgardening.org/mels-mix-resources/
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