Your first DIY greenhouse is as simple as attaching a sheet of clear material to a box. This is called a cold frame and is the best way for a beginner to start with greenhouses. A cold frame can be put together with materials most people already have on hand inside an afternoon.
Read our cold frame greenhouses article for more details about cold frames, and free plans to make your own.
The more serious greenhouse farmer will want to graduate to building a high tunnel greenhouse. Most folks don’t have large quantities of poly sheeting and piping, so you’ll need to make a trip to a local hardware store to purchase some materials. Fortunately, the components for a high tunnel are fairly cheap, and the entire project should only take up a weekend. High tunnels are the cheapest type of large-scale greenhouse to build. As a result, many commercial growers use large arrays of high tunnel greenhouses for crop production.
High tunnel houses are most fragile to wind damage, I know some farmers that put up a beautiful high tunnel greenhouse in Victoria that only lasted a week due to the stiff winds in that city.
One of the best free guides to building your own high tunnel greenhouse is this article by Mother Earth news.
Building your own permanent greenhouse is rewarding and long-lasting. There are many different ways to build a permanent structure, from the a standard 2×4 framed greenhouse to very creative re-purposed solarium. Permanent DIY greenhouses can use glass, or even better, polycarbonate sheets. A properly built greenhouse can take up to a week of time, assuming you have the right tools for the job.
While cold frames and high tunnels are well within the construction skills of an average greenhouse farmer, a permanent hothouse-style greenhouse requires a higher degree of competence Folks without strong framing skills should consider purchasing a pre-built kit from a consumer greenhouse supply company.