Hi Noel,
Building a greenhouse has been bouncing around in my head for a while and the desire keeps getting fed by posts like yours. It's all those tropical Aroids that don't go dormant that I think about. There are so many Arisaema that are hardy up here that I'm searching for the ones that I can give the right conditions. I think part of my problem is getting the soil right, protection from winter wet and such. I have A. speciosum under a spruce and they're very happy. Winter dry I think. I lost A. serratum in a pot no less. I think I over watered in regular Miracle Gro potting soil.