The little greenhouse here at Heartsong, I’m going to call it the Garden Greenhouse, is falling apart.
I put together some ideas about what might be done so I could present them to the Heartsong Families so we can plan for the coming season. But first, a little background:
Here’s a picture of my first hoophouse with my Dad (who bought it for me in 1991) and Nikita. It was a 15’ x 50’ kit with rolled steel arches that I used in two different locations at Tolstoy for about ten years until it finally succumbed to a snow load.
The next hoophouse I built in 2006. It was a quaint one for a community garden called Twin Owls up in the Glenrose Hills.
We ordered just the bent arches and I constructed the rest including a solar-powered, louvered exhaust fan. I used plastic “lumber” made from recycled plastic for the baseboard, should last a good long while.
In 2010 I was manager at the P.E.A.C.H. Community Farm in Cheney. We got a grant from the Rotary Club to buy a 20ft. x 60ft. hoophouse kit. I supervised a couple dozen volunteers who put it together.
Later on when it was the Pine Meadow Farm Center, we entered into a deal with the Natural Resources Conservation Service (USDA) where they would pay for the construction of a mobile hoophouse. Unfortunately, the organization folded before we could complete the project. It was fun and very educational. We convinced the NRCS that we could design and manufacture our own hoopy (see appendix). After some trial and error and research, we bought a tubing bender at Harbor Freight and put on workshops with folks as they learned how to do it and we got our tubes bent.
I have an on-line album of the tube bending workshop:
Then we had a crew of volunteers come a couple of times to start constructing the thing from the plans I’d drawn up.
This was going to be a hoophouse on rails and would have utilized a complex rotation of crops and four different locations for the hoopy to be along the track.
There is a fun little video I took during one exceptionally productive volunteer day when all the cross bracing was manufactured and installed:
So, this is what I have in mind for Heartsong (32ft. x 10ft.):
I have quite a bit of experience building bent tubing greenhouses and I could build a good, sturdy one where the old greenhouse is, expanding it to extend the length of the existing south wall of the shop and shed. My preferred style for the Garden Greenhouse would be with a 4-ft. vertical wall facing south on top of which the arches extend back to under the eaves of the shop roof.
With an eye towards being realistic, we might just set a goal for 2017 to have the first half of the greenhouse completed this season.
I see two distinct options for approaching this:
Option 1) Minimize costs and replace old greenhouse with one styled along the lines of a low-cost, bent-tubing hoophouse similar to what a budget-conscious, time-constrained small farmer might construct.
With my tubing bender, I could bend the arcs from chain-link top rail which is fairly inexpensive but sturdy pipe, attach them securely to the exterior wall of the shop and to the frame in front and then securely fasten a plastic greenhouse film to the arches with wiggle-wire fasteners.
The whole thing can be glazed in greenhouse film (we may have enough greenhouse film on hand to cover the half we build this season, maybe more). The sides and front could incorporate the glass panels there now. We would need to remove the film come winter as a precaution against snow damage, and that would reduce the maximum season extension possible.
Option 2) This option isn’t aimed at maximizing costs. It’s a fairly inexpensive way to maximize the functionality of the greenhouse. This design uses a slightly more permacultury approach, although it still requires lots of plastic. It is based on the same general design and uses home-bent arches made from chain link fence pipe, but it uses long-lasting, very strong, double-wall polycarbonate panels for glazing on the arches.
Some level of attention and care would need to be taken to monitor the snow situation (as with any roof), but this glazing could be left installed permanently and last 20 years plus. The polycarbonate double wall adds a significant extra frost protection compared to a single film while the structure of the channels that run through the panels gives it more strength than simple corrugation.
Option 2 includes a “tromb wall.” A tromb wall is a wall designed to store solar heat. Having a masonry mass for the back wall of the greenhouse would make many plants very happy for years to come. It would protect seedlings from frost and also it would protect the wood wall of the shop from all the watering and humidity that happens on the inside of a greenhouse.
I propose a tromb wall constructed of 8″x3″x16″ cinder blocks or the equivalent. The wall would only be 3″ thick and would be designed to be self-supporting but not load-bearing. My plan would involve tying the masonry wall to the existing exterior wall of the shop.
The tromb wall would cover the two south-facing windows of the shop. Since the little greenhouse has been up, one of these windows hasn’t gotten much light. The other one does and if need be, the tromb wall could have a space in it for that window, but the plan is to have that back wall of the greenhouse be a living wall so likely then there would not be much light from that window either. The shop has those nice big north-facing windows high up that a lot of light comes through. As you see in the design, I propose to add a window with sturdy wood shutters to the shop on the east wall. There are many days when work is happening the shop door is open all day. One of my evening chores is to check that the shop door is closed. I could easily also shut the shutters then to keep the tools safe. You’d lose the shelf space where the new window goes but gain shelf space where the old windows were.
Plus that’s two extra pieces of glass to use in the new greenhouse if we take them out and use them.