"THE 'THREE SISTERS' GARDEN THEORY" - based on several centuries of successful Aztec agricultural practice - is: THE CORN provides a vertical growing medium for the Kentucky Wonder pole beans. THE BEANS fix Nitrogen in their root systems, sharing the fixed Nitrogen nodules with everything around them. THE SQUASH provides ground cover with its broad leaves and sprawl, thereby helping the CHINAMPAS to retain liquid nutrients; also providing shade and lessening the evaporation rate as a living green manure and mulch. You get lots of really nice summer crookneck squash in this symbiotic bargain, too.