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 and fruits.
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 grow the stuff we’re interested in eating.
I used untreated 4×4 and 2×4 cedar wood because it lasts longer than pine, is cheaper than redwood, and won’t warp. I didn’t use pressure treated wood because of the chemical composition and its 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.
Each little greenhouse stands about 6′ feet tall at its highest point. 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. A horizontal roof would take the full impact of a hail stone falling from above and could easily puncture the plastic.
Some might think 4×4 are overkill, but on the eastern plains of Colorado, it’s not uncommon for us to get 55+ 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
I’d love to get a large walk-in greenhouse, but they are expensive. I’m also afraid they wouldn’t stand up to the harsh climate of Colorado.