I was in the middle of planning my garden on paper for May this year, and I had a question. Two years ago, I planted corn in a 4' X 4' garden box. It actually went really well except for one thing. When it was harvest time and it was ripe for picking, we picked it and unwrapped it, and to our surprise, 1/7 of the kernels, mostly on the top, didn't form! I want to try to make sure this doesn't happen this year, so what happened and how can I prevent it?