On the left peas and greens on the right flats of fall sown perennials. In the back a 30 gallon rain barrel I make compost tea in; a Boston fern, Meyer Lemon, oregano basket, sweet olive, asparagus fern. My night temperatures are usually in the 30's. Cloudy days have slowed all the plant growth.

How much does it cost to heat your greenhouse?

When it gets down below 20 degrees my wood stove won't handle the 8' by 26' single pane glass part so I burn propane....its cheap this year; about $3/night on low.

The cacti and succulants don't seem bothered by the cold. I love my new silver torch cactus which doubled in size over the summer.

This is part of the east wall of my used window glass bldg. My probably useless black water jugs at the bottom.

I uncover my cold frame/ventilation excavation on sunny days. this is not well sealed at all and at night I cover with hated plastic and bags of leaves. The ventilation through here in spring is a huge help for everything inside.

Yay! I love pics of other people's setups. Vicarious greenhousing. Your pea plants look so vibrant! I hope they make some peas soon.

Thanks for sharing!

That's pretty cheap. We used an old electric space heater and a small fan when we had our 8x8 greenhouse. We never knew how much it cost to heat it.

You might want to think about using a solar pool cover to help insulate your green house. I just ordered one on ebay which is 16'x28' for about $80.
If interested you might want to check out these links:
http://forums2.gardenweb.com/forums/load/strucs/msg120734489734.html
https://mail.google.com/mail/u/0/?pli=1#label/GardenWeb/14acdacb19e04000

Here is a link that might be useful: Solar pool covers

this year, so far average, I may spend about $300 for wood and propane. That's for about 600 sq. ft. heated to keep things from freezing only.

My 1700 sq ft greenhouse costs about $300 per yr to heat to 40F. That's using natural gas. Winter low averages about 30F so am maintaining a 10F average gradient. Could heat to 32F for considerably less but 40F is much more effective chilling temperature than 32F.

Fruitnut, I admire what you are doing and your obvious knowledge. I bet your houses are very efficient. Its a good lesson for our viewers to see that your gh is probably 3X better than mine in heating efficiency. My set up will gain on yours cost wise when it gets hot and all my leaky windows can be opened. I am actually designing a survival greenhouse that can function if the lights go out for good. Still, its a lot of firewood, lots of work for an old man burning it, and a commitment to managing a greenhouse without controls. I also would like to use natural gas, especially now with all the fracked supply. I also could seal things a lot better with plastic sheeting but can no longer stomach all the plastics.

Nice system, I have an idea or two that might make winter heating a little easier....

The first thing I would suggest is possibly putting up an inside layer of clear plastic in the greenhouse, it will help to keep your greenhouse warmer. Two layers help to trap heat and light much better than one, and provides an insulative space between the two, you want the inside plastic to hang away from the glass giving you a 4 to 6 inch dead air space. I experimented with pallet built greenhouses that doubled as chicken coups in the winter for a few years and I was able to keep them in the 40's without any heat other than the chickens excess body heat. They were small buildings, 6 x 10 8 ft tall with 6 chickens in each.

I also have found using rotting hay and manure buried in the floor of the house useful for creating heat in the winter also, though it has the drawback of being rather stinky and producing a great deal of methane, ammonia, hydrogen sulfide and water moisture. This could lead to fungus problems in a permanent structure I imagine.

I have not tried it yet but I have always wanted to use a manure and hay pile outside the building with pipes run under to circulate air through as a winter heat source, eliminates having the mulch heat source within the greenhouse.

As for stove heat in a greenhouse I picked up a number of old 250 gallon oil tanks and converted on into a stove with a 55 gallon barrel stove kit. These tanks will hold up 1/4 of a cord of wood at a time, I am able to put up to 5 ft long material in it and up to 10 inches in diameter. I made the stove specifically so that I could efficiently burn brush and garbage wood in it as a heat source. I bundle all my brush in the summer into 8 inch or so diameter bundles and stack them and fill the stove with those. I am able to shut the stove down quite well and can burn a load of rotten logs for about 4 to 5 days a load. Burning brush I have to add material in the morning and in the evening. This stove produces mass amounts of heat though, enough to heat that greenhouse about 4 to 5 times over.

If you can get a bigger stove that you can seal air tight you can get it to keep producing good heat for up to days at a time through the winter If you design it to where you can use garbage wood and brush as a heat source it is quite handy and if you can keep it going for a while it handy.

Again, nice system and good luck with your peas, I start growing peas in the house in February, very pretty having all those flowers hanging in the windows.

Mountain, enjoyed your comments. I am no longer buying plastic...its an earthlove thing. I did once put about this much fresh zoo manure in an 18' by 40' greenhouse at a university. Fastest and best seed germination I ever had. don't think it would work actually heating a greenhouse nor do I want to haul that much inside my current greenhouse.

What kind of propane heater did you use?

a Mr. Heater burner which just screws into your tank.