The very earliest greenhouses were constructed with wooden greenhouse frames.
And though wooden frames have been somewhat eclipsed in favor of other materials, wooden frames are still very much in use in greenhouses.
Here's a look at some of the comparative advantages and disadvantages of wood frames:
Most people would agree that wooden greenhouses are the most beautiful type of greenhouse. Or perhaps I should say can be. Because the appearance of a wooden frame is somewhat dependent upon the type of wood used, and how it’s maintained as it weathers and ages.
A greenhouse with a cedar frame, for example, can be a thing of beauty that would grace the most elegant of mansion grounds. A greenhouse built with a frame of yellow pine 2x4’s – not so much.
A wooden-framed greenhouse can be among the cheapest or most expensive of greenhouses. Again, much depends upon the type of wood used.
A yellow pine frame will cost a fraction of what a cedar frame would cost. (Cedar is considered to be among the best of woods for greenhouse construction. Redwood is also favored for greenhouse construction.)
A wooden greenhouse frame is probably easier to work with than any other type of framing material, with the possible exception of PVC pipe. Most anyone who would have an interest in building their own greenhouse would have the simple hand tools needed to work with wood.
Once again – you guessed it – much depends upon the type of wood used. A cedar greenhouse is likely to be intact and functional for decades. But a greenhouse constructed of wood that is susceptible to moisture rot may not last long.
Cheaper grades of wood can be long-lasting if they are pressure treated, but be careful – treated wood can be toxic to plants (and other things). The newer method of pressure treating wood is less toxic than the older, arsenic-based method. But you should still avoid contact between the plants and the wood.
Also avoid water dripping from the treated wood onto the plants, or onto the soil in which the plants are growing. Gardeners who have used pressure treated wood in the construction of a greenhouse recommend allowing the wood to fully dry from the pressure treating process before using it.
Painting or staining the wood can also lesson the possibility of the wood harming your plants. (Be careful about the paint, though. Some paints have chemical additives designed to inhibit the growth of mold, and those chemicals could themselves be harmful to plants).
Wood is an incredibly strong and durable material, especially when compared to other materials on a pound-for-pound basis. A well-designed, well-built, and well-maintained greenhouse will be a very strong and long-lasting structure.
Additional advantages: Wood is a natural insulator, so it won’t draw heat out of your greenhouse as other framing materials would. In fact, wood will absorb heat from sunlight during the day, and release the heat into the greenhouse at night.
Additional disadvantages: The most inexpensive type of greenhouse covering is thin plastic film. This type of covering is difficult (though not impossible) to use with a wooden frame. Wooden framed greenhouses are most often covered with rigid plastic or fiberglass transparent panels.
Wooden frames are bulky in size, and tend to block more light from entering the greenhouse than other framing materials. This is a definite disadvantage during the low-light days of winter.
If you crave a wooden greenhouse, you have lots of choices.
Many beautiful kits are available for wooden framed greenhouses. But if you’re a build-from-scratch kind of person, wood offers the advantage of being easily fabricated to accommodate any type of suitable greenhouse structure.
Just watch out for the splinters!