Gardening in Colorado can prove quite challenging, especially during the spring months when temperatures can swing 50°F from one day to the next. To complicate matters, hail is quite common and can destroy a garden in a matter of minutes. Even pea-sized hail can shred through the green leaves and pit most vegetables. This has happened to us the last few years and ultimately resulted in us restarting from seeds in June, which knocked off a couple months from the growing season. That’s why a greenhouse is almost necessary when growing vegetables in Colorado, and when that’s not possible, even a simple roof covered planter box can save the plants for the harshest of thunderstorms.
Instead of building one large greenhouse, I decided to build a couple around four existing 4’x8′ planter boxes (only two are pictured above). Although we won’t be able to walk into each of the greenhouses, they will be big enough to hang a couple hinged doors on the back-side that will allow access to the vegetables. By backside, I mean the southeastern side of the greenhouse that will not be exposed to the full force of the northerly winter winds.
I used untreated cedar wood because it lasts longer and won’t warp anywhere near as much as pine. I didn’t use pressure treated wood because of the chemical composition, plus it’s going to be in close proximity to the vegetables. So, I do anticipate there being rot at some point, but I don’t foresee that being a problem for at least 10 years, or more. And even then, it will just be the 4’x4′ posts in the ground that would need to be replaced.
The greenhouse stands about 6′ feet tall at its highest point. Each leg of the structure is 4′ tall. The pitch of the roof is at a 45° angle so as to deflect the hail without too much stress being placed on the plastic sheeting (yet to be installed). A horizontal roof would take the full impact of a hail stone falling from above and could puncture the plastic. Also, winter snows could build-up atop the plastic causing it to sag, or even tear.
I used 4×4’s and galvanized metal brackets because I wanted the greenhouse to be strong. It’s not uncommon for us to get 65+ mph winds in the winter, or even in the summer during a downdraft from a thunderstorm. It’s very solid and absolutely will not blow over.
I’m not sure I want to try and garden through the winter yet. This would most likely require some form of heating within the greenhouse. Nonetheless, even vegetables in an unheated greenhouse could start growing in early April and well into late November. Without a greenhouse, its difficult to start growing anything earlier than late May (one usually has to start the plants indoors).
The cost of the materials was right around $110 dollars for each greenhouse. The materials used were as follows:
- 4x cedar 4’x4’x8′
- 6x cedar 2’x4’x8′
- 12x Galvanized Metal 90° Brackets
- Box of 3″ deck screws
- Box of 1.5″ deck screws