I am looking to do a small sea of green grow in soil. I know sqaure containers provide more soil/per space than circular pots. I was planning on using 1 or 2 gallon square containers. For the small sea of green plants, that should be enough soil right? But my real question is this. Can you use rectangular potting trays to pot like 5 plants in a row? It seems like you'd pay less that buying individual pots and the plants will have less of a chance of becoming root bound. Any comments or experience with this?