The days of summer are behind us, and autumn is here. Which can only mean one thing: greenhouse season for all you growers who move indoors during the cold months.
If you don’t have a greenhouse, now is the perfect time to begin exploring your options. Even if you are a seasoned garden veteran, a greenhouse is a logical next step to supplement your existing garden activities.
However, there are a few different types of greenhouses available, and the differences can be difficult to understand at times. Every greenhouse essentially works on the same principles, so one “works” just as good as any other. However, not every greenhouse owner wants the same things from their buildings. Greenhouses can differ in aesthetics, efficiency in heating and cooling, climate control capabilities, durability, ease of use, ease of construction, etc. Before you decide to invest in a greenhouse, you should review the different types of buildings available and their respective pros and cons.
The primary advantage a DIY greenhouse is the cost. They can be inexpensive to construct since they are usually devised and built with at least a portion of available scrap material. Scrap windows, scrap lumber, etc. can all be used, and the quality can be quite good.
A popular DIY solution is a PVC framed structure covered with standard greenhouse film. These are low cost, but as with anything, you get what you pay for. In this case you get a short-term greenhouse structure that will certainly serve its purpose but may also require frequent work as it is exposed to the elements. DIY greenhouses are a good choice if your goal is to have a seasonal greenhouse that is used for a few weeks during the fall or spring.
A drawback to any DIY building of course is that you are 100% on your own when it comes to planning and building them. Plans can be found on the Internet, especially for the PVC greenhouses, and there are threads devoted to DIY greenhouses in many gardening forums. For any direct help though, you’re on your own to figure it out. That’s why these are best for the person who doesn’t mind projects and has the time and energy to devote to them. Once complete they can be very rewarding.
Hobby, Residential, and Backyard Greenhouse Kits
These greenhouses are small, usually no more than 150 sq. ft., and come in kits that include pre-cut, pre-punched frame pieces and panels along with a step-by-step instruction manual. They sometimes even include a video. These kits are perfect for small spaces and for those that don’t have the time or energy to devote to either a DIY project or a larger project. They work well as a place to start seeds for the spring and overwinter plants. They also work great as a place to maintain flowers and other decorative plants. They can, however, be a bit small to do something like grow a vegetable garden in the winter and the costs of maintaining a temperature conducive to that can sometimes be prohibitive.
Hobby greenhouses typically have extruded aluminum frames and twin wall 4mm polycarbonate, although some have thinner, single wall polycarbonate. Both coverings are rigid, but the single wall has very little insulation value comparatively, and so costs of maintaining a suitable temperature can be a little more in these.
Professional + Consumer = Prosumer
Most of the greenhouses I will call prosumer are still lumped together in the hobby greenhouse category. While technically this is true, the size and cost of these structures really makes them much more than just a hobby. Sizes can run from 12′ x 12’ to 20′ x 20′ and above, while costs can begin around the $5,000 dollar mark and go beyond $20,000. I call this category prosumer because it is a serious commitment to make for “just” a hobby and because any of these structures would fit right into a retail growing operation as a show house, a research house, a seeding house, etc.
Prosumer houses usually have a slightly higher quality aluminum frame, and coverings are most often 6 or 8mm polycarbonate. Often, they have glass as a covering option as well. They are fairly customizable as to the look and can be made to fit any grower’s exact needs. Many of the prosumer houses can be structurally rated, complete with engineered prints. They may be slightly more complicated to construct, and their foundation is usually going to include concrete footings, a concrete slab, or concrete perimeter wall.
In agriculture and gardening, a cold frame is a transparent-roofed enclosure, built low to the ground, used to protect plants from cold weather. The transparent top admits sunlight and relies on the greenhouse effect to reflect radiant heat that would otherwise escape at night. Essentially, a cold frame functions as a miniature greenhouse season extension device.
These structures are interchangeably called cold frames, hot houses, and hoop houses, among other names. The important thing to know about them is that they are non-engineered greenhouse structures. This just means that an engineer has not signed off on the structure, but that they are field tested to withstand, typically, 70mph wind and corresponding snow loads. Their non-engineered status and inexpensive materials list makes them a very affordable, similar functioning structure compared to full commercial buildings. Often, they are used for production houses in a commercial growing setting.
They almost always have a steel frame of some sort and 6mil polyethylene covering in either a single or double layer. They are a “real” greenhouse in every way except price. A full package – including standard equipment – in a size of 20’ x 36’ can be purchased for about $6, 000. There are also much smaller backyard versions that can be purchased at an extremely low cost.
These buildings are the most versatile and feature filled structures of all. They are useful in educational, research, and commercial applications and can be as inexpensive as $20,000 all the way up to $100,000 and beyond. These buildings can be gutter connected, partitioned, hundreds of feet long, multiple climate zone behemoths, or they can be relatively simple 35′ x 48′ teaching greenhouses with just a heater, fans, and shutters.
They will always be structurally engineered to a specific wind and snow load rating, constructed with load bearing sidewall posts and usually glazed with 8mm twin wall polycarbonate. There are multiple sizes and several styles to choose from.
These categories are by no means hard and fast. There certainly is some overlap, and keep in mind that what’s commercial to one person may be hobby to another.
Drew Landis is Social Networking Coordinator for an online greenhouse retailer.