A greenhouse is a wonderfully valuable space for gardeners, and come late fall, it becomes a haven to protect plants for winter and do late sowings of cold-hardy crops. Even an unheated greenhouse can be 10-30°F warmer during the day, and several degrees warmer at night, providing an ideal, protected environment for plants.
I worked in several gardens with greenhouses, including one with two large restored Victorian glasshouses. They were a great space to overwinter plants indoors. I've also grown microgreens in there year-round, and propagated plants indoors in late fall. November isn't just a time for fun jobs like propagating, though. I also found it an ideal time to prepare for winter and spring by cleaning and sorting the space.
