Do you know where I can get step-by-step plans on how to build a greenhouse?
This publication from the University of Minnesota, Cold Climate Greenhouse Resource, lists all the basics of greenhouse growing including different types of heating (active and passive). They use real life examples from growers, lots of photos, costs, etc. There aren't specific plans, but if you're handy you can easily recreate these designs. Also included is an extensive bibliography which may include detailed plans. Hopefully you can contact one of the resources for a start.
Here are several sets of plans and considerations for building a small greenhouse:
- Hobby Greenhouse Plans from Alabama A&M and Auburn Universities
- Hobby Greenhouses publication from the University of Georgia Extension
Good luck and have fun. Hobby greenhouses are a great way to extend the vegetable gardening season.