Great deck Preston. You should be able to grow lots of veggie in that space.
You already know that the plants like your tomatillos and such will need the most sun, every little bit they can get. Things like lettuce, etc. can take a lot more shade and grow well.
I can't wait to see how you set it up. I love your idea about using casters, easy to follow the sun for the sun lovers. I really like this type of planters, as it keeps the container and water off of the railing. You could probably come up with a homemade/recycled idea?
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