This cold frame is super sexy:

I liked the braids and the back patch myself Glad to see someone else is using my patented seed dispersal techniques. I do that with nettles at least once a day this time of year. everywhere. muhaha

I'd love to see an update on how well this worked, what the internal temperatures were during different parts of the year, etc. I've heard that in France in the 1800's, horse manure was used to heat cold frames and more wintertime produce was grown this way than anywhere else in Europe at the time. I am in the process of building an underground cold frame that has a couple of feet of hugelkultur below it -- here's the progress so far: http://woodforfood.blogspot.com/2014/04/underground-cold-frame-part-i.html

If anyone has suggestions on where to take it from here, I'm all ears. I'm hoping to slant it toward the southwest by building the walls higher on the northeast side, and then I'm thinking to attach the window to a wooden frame that can sit on top of the rock walls.

Happy growing!

With fresh horse manure it's called a hot bed, and I tried it once myself. In January, I dug a hole, filled it with manure, then placed the soil back on top, with a cold fram over. It didn't get hot enough to actually work, though. Maybe the manure wasn't fresh enough, or maybe there wasn't enough of it. I consoled myself with the thought that it at least fed my worms

GF, that is interesting! I'm glad your worms were happy and sorry to hear the heat didn't pan out. About how big would you say the hole was? Any idea what volume of manure went in? My underground cold frame doesn't have a massive amount of manure under it, but I'm hoping it will be somewhat heated with the combination of a decent amount of manure and the hugelkultur wood, about two feet below it plus whatever I put into the base of it before planting. It's pretty deep so I should be able to load it up with more manure.

I have one bed called the "Aspen Hotbed" because it has a lot of manure... over 10,000 pounds in the one bed... http://woodforfood.blogspot.com/2014/03/aspen-hotbed.html. It grew very nicely last year and this spring I started constructing a mini greenhouse over it to capture some of the heat. Then I had a dust devil problem (http://woodforfood.blogspot.com/2014/03/dust-devil-eats-greenhouse.html) and I reconsidered my design! This mini greenhouse was different than the one that got eaten by the dust devil, but not strong enough that I felt confident following through and putting the walls up (yet). Our place is really windy. It seems it's always something! I wonder for how long 10,000 pounds of manure/hay mixture will give off heat. I guess I need a soil thermometer with a really long probe...

About how big would you say the hole was? Any idea what volume of manure went in?

It was about two feet deep, by about 4 feet by 4 feet. I couldn't say exactly how much manure it was, but we had to bag it up ourselves and cart it home in the car, so it was not a huge amount! I would say it filled the hole almost to the top. I can remember getting in and stomping it down to make sure it all went in. I wonder if the amount of soil that went back on top was also a factor in it not getting very hot? I don't know; I read about this procedure in a (conventional) gardening book, and watched one youtube video about it, so that's the length of my knowledge and experience.

That said, I would definitely like to experiment more. Maybe I'll call up the stable again and ask if we can come get some more. This time I might try just piling the manure on top of a bed and covering it with a much smaller layer of soil.

Hot beds need really fresh manure. Most stables here have a huge heap that you can go and dig from, but it may well have been sitting out for 6 months and cooled right down. Great for growing, less good for heat.

Yes, it may have been older manure. It smelt pretty strong, but we noticed the stables only had about five or six horses altogether. Perhaps it was just that top layer which was so pungent, and they'd been building up the pile all winter.