Have you ever admired those nice commercial-style high tunnel greenhouses? If you’ve checked the price, you know it can take some real money to get into greenhouses. But “four seasons gardening” pioneer Eliot Coleman has a design that is easy to build, portable and affordable.
I mentioned in my Solar Bike Station article that I spent the month of September as co-instructor of an “Energy 101” class at the Sustainable Living Center at Maharishi University of Management (MUM) in Fairfield, Iowa. This unique school offers bachelor and masters degrees in Sustainable Living, and “Energy 101” is one of the core classes in their curriculum. In addition to learning basic physics of thermal energy, electrical energy, chemical energy etc, the students tackle some hands-on projects of their own choosing.
Two Sustainable Living majors, LaToya and Ryan, chose to partner up and build a greenhouse form scratch, to show how the growing season can be extended with no additional heating. I had the honor of coaching them. Spending a few sunny fall afternoons building a greenhouse…what could be better? With a good set of plans, the right tools and materials, and, most importantly, a couple of strong youngsters to do all the work, I almost felt guilty about how much fun I was having at work. Almost.
The design we used was developed by the great Maine gardener Eliot Coleman, whose books like Four Seasons Harvest” and The New Organic Grower have revolutionized small farming and gardening. Coleman designed this “Gothic” top greenhouse to add some extra width to the conventional round-topped high tunnel, and to make modular sections that would be easy to move, but could be fit end-to-end to make longer units. The 1 3/8” galvanized pipe and most of the fittings are off-the-shelf chainlink fence parts from Lowes garden center, along with a few pieces of EMT. A link to the special benders needed can be found at the end of the article.
The design is excellent, leaving almost zero wasted pipe scraps. We screwed the benders down to the deck of my little trailer with big Grip Fast screws, but the instructions showed bolting it to a picnic table. Regardless, you need something stable and heavy, because bending the 1 3/8” pipe takes a little “oomph.” Both Ryan and LaToya did an excellent job of measuring and cutting all of the pipe, drilling all of the holes and bolting the whole thing together, with minor direction and adjustments from the “Old Timer.” They worked after class every afternoon for an hour or two, and had the frame completed in less than a week. When they did their cost analysis, the materials for the frame along with the bender came in at just a little over half of the price of a similar commercial greenhouse frame, with no shipping cost other than a run to Lowes with the little trailer.
The Hoop-house can now be covered with a single or double layer of polyethylene plastic. According to Coleman, each layer of protection creates a microclimate equivalent to moving one climate zone south. In other words, the climate inside the greenhouse in Fairfield Iowa will be the equivalent of central to southern Missouri or Kansas. That means that come spring, they will be able to plant weeks ahead, and harvest some crops, like spinach and kale, all winter long! This is a great project for a school garden, community garden, or anyone who wants to grow their own delicious, healthy vegetables.
You can find the Quick Hoops bender for around $60
