Just wondering, could I grow our hills (3 rhizomes per hill) within a 2' diameter, 2' deep, bottomless cylinder? Trying to think of ways to cut down on weeds and contain water.
2' diameter is a good space for 1 rhizome. With 3 they'll start to start to grow together and compete for water and nutrients. Which will result in less yield.
^ Yup, seriously, that'd be a tangled mess in short order - both above and below ground - as they compete for food and sunlight.
Bottom line is you need more than a foot of spacing if you're going to give your plants a chance to really produce...