Compost based greenhouse heating.

I have enough material to build another greenhouse about 15' wide x 30' long and access to a large pile of compost and am looking for suggestions as to how much compost would be needed to stay cool enough to grow plants in during the winter, but warm enough so as to not die during the winter also. I construct my greenhouses out of pvc pipe and attached to the ground using 4ft rebar stakes so they are really easy to move and replace the compost when it burns out. Any suggestions?

where are you located? what sort of compost?

I'm a little northeast of seattle. The compost from what I can tell is various yard clippings, leaves, branches, etc.

is the pile of compost hot right now?

It's not being actively managed, the yard waste is dumped and occaisonally moved to form a more compact pile. Parts of it are warm, others are not. There is still a lot of organic matter that is not been decomposed so I think it could still be managed into a very active pile.

it's really hard to say without seeing and feeling the material in question. the local microclimates involved complicate things, too. is it near a south slope that will increase solar gain? does it get hit with a lot of wind? in the end, you won't know until you try.

I don't think getting too hot over the winter is going to be a problem for you, though. my guess is that 18" of active compost will give you a nice little bit of bottom heat, and you'll want a good layer of dirt over that. cloches over your beds inside the larger hoop house will help a lot, too.

for my own greenhouse, I'm considering burying some 1/2" tubing in a big pile of wood chips and plumbing it to a radiator inside. not sure if I'll need it yet, but it's something I'm thinking about.

We're in a much colder climate - mountains of northern Vermont. Anything that extends the season is wonderful. I have done numerous greenhouses and cool frames heated with manure/plant based compost. It has worked great. I'm planning on doing one on a much larger scale, probably about a quarter acre. In addition to the compost heating we have used and plan to use animal heat.

Cheers

-Walter
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
Read about our on-farm butcher shop project:
http://SugarMtnFarm.com/butchershop
http://SugarMtnFarm.com/csa

tel jetson wrote:it's really hard to say without seeing and feeling the material in question. the local microclimates involved complicate things, too. is it near a south slope that will increase solar gain? does it get hit with a lot of wind? in the end, you won't know until you try.

I don't think getting too hot over the winter is going to be a problem for you, though. my guess is that 18" of active compost will give you a nice little bit of bottom heat, and you'll want a good layer of dirt over that. cloches over your beds inside the larger hoop house will help a lot, too.

for my own greenhouse, I'm considering burying some 1/2" tubing in a big pile of wood chips and plumbing it to a radiator inside. not sure if I'll need it yet, but it's something I'm thinking about.

Do you think 24-36" of compost would be too much? I could literally bring 6ft of it in if I so felt inclined.