Simple compost heated cold frame/ greenhouse for seedlings

After seeing Ben Falk's Jean Pain mound heated greenhouse, I was reminded of this article from a few years back on making a simple compost heated cold frame
For the last few weeks of seedlings which have been started indoors. The idea is basically to build a 3ft cubic compost pile, then a small greenhouse over the top. This seems like a great solution for home scale gardeners without a heated greenhouse in northern climates. I believe the article came out prior to the readily available hoop bender, which could be utilized to make the frame. Anyone have experience with this model or others

http://www.mofga.org/Publications/MaineOrganicFarmerGardener/Winter20072008/GrowHeatLovingPlants/tabid/842/Default.aspx

Hi George,

I'm using hugelkultur as the compost to heat my cold frame from below, and I've got the whole thing below ground to help insulate it: http://woodforfood.blogspot.com/2014/04/underground-cold-frame-part-i.html 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. It makes a lot of sense but I haven't found any drawings of the designs they used back then -- wouldn't that be neat?

If anyone has suggestions on where to take it from here, I'm all ears (see photos on above link for the stage it is at right now). I'm hoping to slant the cold frame 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. Have you seen any designs that include the cold frame being underground?

Julie Ashmore wrote:
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. It makes a lot of sense but I haven't found any drawings of the designs they used back then -- wouldn't that be neat?

Bearing in mind that this was before cars and there was widespread concern that horse manure would end up burying cities. They had quantities available far beyond the wildest dreams of a small farm with a couple of horses. I suspect that you would be able to nurture a small number of plants through a winter but you would need to find a regular and plentiful supply of manure to take it beyond hobby scale. These days most stables dose their horses with all sorts of antibiotics so the manure is rather less than ideal.

Michael, that is a good point -- the sheer volume of horse manure that would have been available. I definitely can't match that. But I would think the hugelkultur wood would generate some warmth, too. I am lucky to have a neighbor with two horses, and she gives me all the manure I want. I think I will beef up the manure supply in the base of the underground cold frame itself. I made it extra deep so there should be plenty of vertical space. Thanks for your comments!

Hugelculture wood is unlikely to raise any worthwhile heat - manure is a hot (bacterial) composting process, where as hugel is a slow, cold and predominantly fungal breakdown.

Growing Pineapples with Manure

Notice that they needed 30 tonnes of horse manure to ripen 10 pineapples.

This is a cross-forum link, so I have placed it in two forums.

Jean Pain compost mound heat for hot water loop to hoop house/green house, low tech and very good data:

http://www.instructables.com/id/Compost-Heating-System/?ALLSTEPS

That is quite the set-up, Ty! Thanks for sharing. I may try something like this. It was great to see they followed up with data -- "Our mound produced more than 6 million BTUs over a period of 12 months, including a freezing New England winter." That is with predominantly carbon materials, with a casual suggestion, "add manure, if you have any." Michael, I have to think that hugel would produce some heat, even though it's not "hot" like manure. Even a pile of leaves can be very warm to the touch at the center of the pile, in autumn as well... I think I need to find a way to measure the soil temperature about 2-3 feet deep in the center of my hugel beds. Any suggestions on a device that would have a long enough probe to do that? Thanks so much for your comments!

Some small amount of heat may be produced - but comparing brown leaves to a hot manure heap is much like comparing a candle to a bonfire.

A pile of leaves is a very effective insulator as well, so often will feel warmer and drier than the surroundings. You can make a really really warm and comfortable winter survival shelter from twigs and leaves heaped up. Do a search for 'debris hit' to see what I mean.

What appears to matter though is the rate at which heat is produced, rather than the temperature that can be reached. Similar conversations happen with solar power - you can make an insulated box that gets hot enough to warp and melt plastic but is still lousy because the rate of energy gain is too small.

By all means try it but my own experiences suggest it is unlikely to be successful. After all - farmers and market gardeners have been using these techniques for generations and have always advocated tonnes of the freshest horse manure they can get.

Urgh. Silly iphone keyboard 'debris hut'