Question: What is the best way to reduce humidity in a greenhouse without reducing temperature too much? My tomato and lettuce plants got quite moldy last year, and I'm guessing it was because it was so humid.

Answer: Your tomatoes and lettuce have fungal problems because of high humidity and stagnant air. That's why commercial greenhouses always have fans circulating the air. I'd suggest you install a house fan in the greenhouse and run it during the day to get air flowing and reduce the humidity a bit. The larger the greenhouse, the bigger the fan, but a house fan should be okay for a small greenhouse.