Country Lore: Build a Free-Standing Greenhouse

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Clara Coleman loves her new greenhouse.

It must run in my genes because after my successful first winter of growing greens in a hay-bale-and-plastic cold frame, I was eager to try a real greenhouse. I wanted to walk into an enclosed space to tend my greens throughout the snowy Rocky Mountain winter. Rather than a hoop house with rounded sides, which wouldn’t handle heavy snow, I decided I needed a wood-framed structure with a sloped roof and straight sides to withstand Colorado’s windy, snowy winters.

With the help of a book my father, Eliot Coleman, gave me, Greenhouses for Homeowners and Gardeners by John W. Bartok, Jr., my boyfriend and I designed a 200-square-foot wood-framed, plastic-covered, free-standing greenhouse. We purchased the wood and building supplies from a local lumberyard. Because railroad ties border my 25-by-8-foot garden, we simply built a base on top of the railroad ties with 2-by-4s. Next, we drew a pattern on our deck to create the 7:12 roof pitch and 4-foot tall walls. Laying the 2-by-4s flat on the pattern, we cut the wall and roof rafters at a 32-degree angle and attached a ½ -inch plywood gusset (taken from a pattern in the book) on either side of the 2-by-4s for structural support.

We used additional gussets at the wall-to-roof connection and at the ridge. We attached each frame at 4-foot centers to our base plate and slipped our 2-by-4 ridge into place. At one end of the greenhouse, we built a 2-by-5-foot door frame with a homemade, plastic-covered door and at the other, a 2-by-2-foot window frame with a similar homemade window. We covered the open end wall spaces with plastic and secured it with ½ -inch plywood strips and screws. Finally, we were ready for the last but most tedious task: securing the large sheet of plastic over the entire green house. On a windless day, we draped the plastic over one side, secured it with ½ -inch plywood strips, pulled it taut and attached it to the other side.

When I set foot into my greenhouse for the first time, I was thrilled to experience that wonderful, earthy greenhouse smell. Overall, the process was pretty simple, and it only took us about $325 and two weekends to complete the greenhouse. Last fall I planted arugula, green and red ‘Oak Leaf’ lettuces, spinach, mache, ‘Bull’s Blood’ beets, Swiss chard and ‘Winter Density’ romaine lettuce. I had two planting dates — September 1 and 15 — which produced edible crops by October 7 and 30, respectively.

The only hard part is remembering to open the door and window on warmer days for ventilation. A good rule of thumb I learned from my father is to always err on the cooler side with the greens. They can recuperate much easier from a little cold than from the wilting heat. After all, this is a winter greenhouse! The joy of being able to go out and cut fresh greens on a snowy morning far outweighs the effort it took to build it.

Clara Coleman
Woody Creek, Colorado