If i could only grow three crops where i live in zone 6a, they would have to be kale, squash and beans. I’m pretty sure kale is the thing i would grow if i could only grow one thing. Kale probably isn’t a subsistence crop (although the seeds are nutritious and high in fat, so that’s something one could pursue) but assuming you have access to a grocery store for your caloric needs then kale provides the vitamins and minerals to keep you healthy.
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