When following the Gro-biointensive guidelines it is recommended that 30% of the growing space be devoted to high calorie root crops. These 7 plants have been studied intensively and provide the most calories per square foot of anything you can grow! Even at 7300′ we have successfully grown them all outside except sweet potatoes. They are: leeks, garlic, parsnips, salsify, potatoes, jerusalem artichokes and sweet potatoes. If your garden is small and you want the most bang for your buck, consider growing some of these. We love them all!