Lammas Part Four - A Greenhouse Made of Mud

The cob greenhouses which Nigel and Cassie had constructed were both charming and functional. Of course they had glass in too, for solid mud does not make for a good greenhouse. But the glass frames were encased in cob and the back wall was entirely made of cordwood and cob. The overall effect was of a light, warm growing environment, but one where the natural properties of the cob regulated the environment, stopping it from overheating during the day and releasing its stored warmth during the night.
Inside there were grapes and peaches, tomatoes and peppers as well as medicinal plants, for Cassie is a herbalist too.
One had a hügelkultur bed - a permaculture system where a growing bed is started off with logs, sticks and brushwood before being covered with layers variously of manure, rotting grass, straw and soil. It is supposed to provide long term fertility and a rich, living soil. It is an idea which I intend to try out in my veg plot.

Two sections of the greenhouse were already built. We were completing the structure. On the other end of the greenhouse was a cob room which had been given over to Cassie's daughter. What a wonderful space for a teenager.
I worked initially on the back wall which was not quite so straightforward as it seemed, having a bit of a lean and a bend going on. We were working on ladder staging with one person on each side of the wall.



Meanwhile others were working on the fill in between the window frames. This was the slow bit as there was not space for cordwood. The cob was sagging too, so we added straw to give it more structure. There was lots of banging in of nails too, known as spragging. These nails give the cob something to key into and hang on to.




Progress on the first day was slow. It was day four before we came back to the greenhouse with a determination to make faster progress. The A-team were on the job today! Progress around the window frames and over the top was faster. We were going through cob mix like nobody's business. There were occasional deviations for creative sculpture in the walls. There were troll-like faces, fertility symbols, a lizard and, of course, a cob-web.

















A cob greenhouse would be lovely back at Swallow Farm, but it is a huge project and one which I am not sure will ever happen. We'll see.
Maybe if the cob was mixed by animals and I had a team of volunteers to help out...