It's not what most people would consider 'greenhouse' crops, however, it would give the corn the heat required to reach maturity, and the beans the protection they need at the ends of the seasons.
I figure a dedicated bean/corn greenhouse should equal 2 1/2 garden rows of beans. I started planting 6 rows of beans due to our short seasons, which makes for back breaking work when they're ready, but most years gives me enough beans to last the winter, even if an early frost wipes them out after a couple of weeks. I'd still plant a couple of rows in the garden, especially to start, but not 6- saving me space and time!
Corn, on the other hand, I only plant every few years when we have an early spring. It's done well in the greenhouse before, in the shortest of summers, but I'm rarely willing to give it that much space. 3 rows of corn would be more than I've EVER harvested before. The prospect is rather exciting...
A new area for vines means I can finally plant the Red Seeded Citron. After reading a bit more, it seems that it's simply the ancestor of the watermelon, basically the white around the rind, except all the way through. I already make preserves and jam from watermelon rind, and it's not a favourite here. They may not be worth the effort. I'll try them this year and see how it goes.
Greenhouse #5 next year? Hmmm... More tomatoes? More beans? Am I out of crops that require shelter?