This post below was written for us by our friend Scott Allison. As we all know, straw has multiple uses and this is a pretty easy/economical/functional use for bales. This is a quick a simple project that you can do to extend your growing season. The details below are for a simple, what I would call “annual” cold frame. In other words, this would need to be rebuilt each year because it is not plastered and protected from the elements. That said, it could be upgraded with ease to be a permanent structure if that’s what you are after. Here’s what Scott had to share:
As a sustainable builder I have always loved working with natural materials and I myself have a fondness for reusing as much as I can whenever I can. So when my friend and long time client asked me about building a cold frame on the south side of her little urban farm I thought it would make sense to work with straw bales.
The project took me just a few hours to complete and I was working by myself.
First I built what I understand to be a Ben Franklin style foundation with out infill other than a few cross red bricks to keep my spacing. With hindsight I would suggest a few screws and fastening some 2×4 spacers to keep the foundation from falling on its side while placing the bales.
Second I placed the bales side by side. Two high on the north side and a single row on the south. Then I took apart a single bale and stepped the sides down, filling in where I needed to.
Next, I placed wooden spacers on the top of the north and south rows and screwed them into wooden 1×1′s so they would support the poly carbon plastic panels on top. The 1x material can be doweled into the bales to keep it in place and the poly roof attached with roofing screws (with washers) to the 1x runners.
I planted a few broccoli, arugula, lettuce, collard greens, and chives and they all seem really happy. The night that I built the cold frame turned out to be the second frost in our area; however, the temperature inside the cold frame stayed well above freezing. The broccoli is now blooming so I think it’s gonna work pretty well. I intend to place some red brick towers in the north side corners as thermal mass and I imagine a few candles (in coffee cans of course) might go a long way to make for a really warm place to grow food during the winter.
I hope you enjoy the concept and creation,
About the Author
Andrew Morison is a specialist in straw bale and green construction. He has shown thousands of people how to build their own straw bale projects through his comprehensive series of instructional straw bale, concrete foundation, and plastering DVDs, as well as his hands on workshops. You can check these out at www.StrawBale.com/store.
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