YOU NEED SOME BOXES... It's a fact, if you have not much space in the ground, the boxes work almost as well as the ground (well, not that well, but pretty fine) well, I buy mines. See, nearby my home there is a market where sellers use wooden boxes to transportate avocado, so I buy them really cheap for $0.12
almost a gift... so, you could look at those boxes where those delicious Californian grapes are transportated, and save them from the trash, that would be for free...