Editor's Note: This article was originally published on December 4, 2007. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
For many people, "Greenhouse" conjures up the image of a wood or metal framed glasshouse with a hefty price tag. However, new materials and the ingenuity of inventors have made new, more affordable options available. With the basic greenhouse kits, simple tools and a helpful assistant, you can have your greenhouse built and usable within a day's time. Below are a few options to consider.
Hoop or Quonset Structures
My first three greenhouses are in this category, and all of them are Weatherguard greenhouses that I purchased originally from Northern Tool. These structures consist of both curved and straight lengths of pipe, and tee or cross fittings that serve as connectors between pieces of pipe. The curved sections of pipe form the "hoops" that give these greenhouses their name. The kits come with nylon rope to use in holding the partially assembled structure together while you continue working, but I found a better solution for this. I decided to install small eye bolts on each of the tee and cross fittings and then used bungee-type cords between fittings to hold the pipe on with. With the Weatherguard greenhouse kits, the pipe pieces do not fit snugly, so either the nylon rope or the bungee cords are a must if you want to keep the structure from collapsing on you as you work.
The first time I assembled my large greenhouse, I used fabric-covered bungee cords, but found that these deteriorated rather quickly under the south Florida sun. I now have the black rubber bungee cords in place on the large greenhouse. With the small greenhouses, I decided to opt for plastic coated chain, old springs from a trampoline and quick links instead of the bungee cords. The spring-and-chain option is much longer lasting and is a good option if you happen to have access to some old trampoline springs. Both the bungee cords and the spring-and-chains make the greenhouse frame such that it pops back into shape after being subjected to stress, like from heavy wind.
There are other hoop or quonset greenhouse kits available in a variety of sizes. Some of these use swaged pipe (one end of pipe enlarged to allow the adjoining pipe to slide into it) and special clamps that join the purlins (horizontal runs of pipe) to the "hoops". This design serves the same purpose as the tee and cross fittings plus the unswaged pipe sections provided in the Weatherguard greenhouse kits. For larger greenhouses, you may need ladders or some kind of lift to help get pipe sections in place.
Once your hoop or quonset frame is complete, all you need do is install your greenhouse covering and you are ready for benches and plants. The kits come with a plastic covering but in the summertime you may want to replace it with shade cloth to prevent your plants from overheating. I use one of my small greenhouses for delicate or finicky aroids and even though I'm in south Florida, I need the greenhouse to keep the rain off these plants. If you have plants like that, you'll need to keep your covering on and just allow for proper ventilation to keep the plants from burning up.
While I have not obtained one of these personally, I have a sample of the Solexxtm panels and am quite impressed with it. The panel is similar to what is used to make plastic mail baskets I've seen at the post office and which they sometimes lend to you when you have a LOT of mail to pick up. It is like a translucent white plastic version of corrugated cardboard, only much stronger. Even if you do not purchase a Solexxtm greenhouse kit, the Solexxtm plastic panels are worth considering as a replacement for plastic sheeting on your existing greenhouse.
The overall design of these greenhouses is quite durable and functional as well as simple to construct, although a bit pricier than the hoop or quonset type of greenhouse. A plus is that most models include bench frames as an integral part of the structure. You can find out much more about these greenhouses at the Farm Wholesale Ag website.
Geodesic Dome Greenhouses
I include these because firstly, they are my all-time favorite greenhouse structure and secondly, a DGer chronicled his construction of one from scratch in a thread, Building a Geodesic Dome Greenhouse on the DG Greenhouse forum! The picture shown here is from that thread. I built one of these many years ago myself from scratch, but that was way before there was a Dave's Garden. These domes are futuristic, and being inside one had me feeling as though I was in a spaceship! Nowadays, connector kits or complete frame kits are available for building geodesic skeletons for use as greenhouses and other structures. You can get kits for a mind-boggling variety of sizes and designs. A plethora of examples are illustrated and available at the Worldflower Garden Domes website.
Building a geodesic dome is not for the faint of heart, but if you are precise with measurements and good with tools, the project is doable, and the result is spectacular. For the skilled do-it-yourselfer, constructing these greenhouses can be less expensive than the traditional wood or metal framed glasshouse kits.
Other methods of erecting a greenhouse can be found, such as specially designed brackets for joining 2 x 4s into a barn-type frame, or the "star plates" for joining 2 x 4s into a basic geometric dome frame. What you choose depends upon your budget and your needs, but that you can choose an affordable greenhouse option now is no longer in doubt.