I been attempting to find what would work best in getting my small greenhouse hot to maximize the growth of what grows there. I reside in St. John's, Newfoundland, Canada and this city receives more cloud, rain, and wind then in any other major city in Canada!

First, let me share some of what I have checked out:

I have heard that one could try using a dark colored container, and even go so far as to lay charcoal on the surfaces where not growing to absorb heat. Also, use some sort of water container, and likewise, large rocks, to absorb heat in the day to later give off heat as it cools in the night. (And placing it where it gets the most heat, south side generally)

What I want though is a super heated greenhouse...and I am wondering if anyone has heard of any creative ideas without having to use electricity?

I would love to hear what others have to say, brainstorm etc....

Great topic of interest in growing figs in cold climates!

Applying layers of clear bubble wrap all around the greenhouse should increase the temperature by increasing the insulation and trapping the heat in.  You would need to cool during the summer.  

1) Google "solar furnace" and apply those concepts to a greenhouse.  You could boil lead in the Arctic if you just concentrate enough sunlight.  As you mentioned, use thermal masses like water or rocks to absorb the heat from the concentrated sunlight and radiate it over time.

2) Google "rocket stove heater" and build a big one that runs the length of a greenhouse.

Best of luck, if you've got a good engineering mind, you can do it.

Geothermal would be a great option. Isn't there quit a bit of that in your area? It's always on and easy to control.

Anything related to the sun doesn't work well in a cloudy climate. If solar heats well on a cloudy day then as soon as the sun comes out it will incinerate your figs unless you have very good controls.

The first thing you should do is move to S. California -lol . But since that may be the least practical..........

The rocket stove is a very good idea. If you can build one that burns as efficiently as is claimed, that may be a good alternative for you. Also, depending on the size of your GH those candle heater pots could be an inexpensive route to go as well. Especially if you can find (or order) some of those long burning emergency candles: http://www.youtube.com/results?search_query=candle%20heater%20pots&sm=1

I wish you the best but, figs in Newfoundland, really ;) ? It will be interesting to hear about the results you experience there. Please keep us posted........... 

Is anyone experimenting with manure-based hot bed techniques?

I heat my greenhouse with an outdoor wood furnace. I also heat the house and garage with it as well.
The only electric you would use in the greenhouse is for the fan. I was able to keep the greenhouse at 42 degrees even on the coldest nights. There where times when it got down to -15 outside at night and that's not including the wind chill.
The downfall is that you need to like to cut firewood. It gets to be a pain.

I looked at some of the videos on solar furnaces, and there are some creative examples out there, that would work for my small greenhouse. My purpose is to get that temperature up where our temperatures are generally considered cool as compared to the mainland. The woodstove or a rocket stove heater would be an asset for a bigger greenhouse. 

If one can grow grapes in Newfoundland, then figs should be able to be ripened here too.  For anyone interested, a good example of grapes grown in Newfoundland would be the following link: http://www.dccw.ca/

Here in St. John's, though, we have more challenging fluctuating cooler weather. One can only try and just maybe I will have something to show for it,

Rick's suggestion of a manure base hotbed is also a good idea for any greenhouse. Heat is generated from the decomposing organic material and you're making compost to boot. Only drawback is it does require a little extra space which is usually at a premium in a GH.

Ron, How many days of sun would you say you average in the summer? One nice advantage for you is the fact that you get much longer days in summer than we do further south. Some folks in AK are known to grow some really huge vegetables because of the many hours of summer sunlight they tend to get.

It will be interesting to hear back from you over the next couple seasons to see what kind of results you get. 
 

Glad you took the time to look into solar furnaces, zhrob1.

One point of clarification, as I may have been misleading: I was not implying that you concentrate all of that extra sunlight onto the plants (since that would incinerate them).  I would indeed bounce a little extra light into the plant area (maybe 30-50% more than would naturally hit it?), but the copious concentrating of extra light would occur in a separate (though connected) solar furnace.  You could, for example, concentrate enough light into the solar furnace to make a large amount of hot water.  If this water is well insulated, it will hold the heat well over time; if you circulate this hot water through the connected plant house (which should also be well insulated), you can "superheat" your plant house without incinerating any plants, and by just using simple controls.  So just to re-state, I'm talking about two separate but connected structures: your greenhouse with your plants in it, and a solar furnace that serves as the heat catchment system.  Could be as simple as two tunnels next to each other, where you bounce perhaps an extra 30% more light into the first one (where you grow the plants), but an extra 300% or whatever into the second one, with the two tunnels connected by plumbing.

Also, I would create a system in the plant house to moderate air temps.  This can be done by blowing the hot air at the top of the greenhouse down through a system of perforated culvert piping buried underground.  Essentially you're pumping heat from the air into the ground, which not only makes the air more hospitable, it warms your soil to promote better root growth.

These ideas use some electricity (circulating water between the solar furnace and the plant house, and circulating air underground in the plant house), but they don't use much.

The University of Manitoba has a passive solar greenhouse research project that you may find helpful, though I don't think they've gotten into solar furnaces yet.

Good luck on your fun project :)

There's an outfit in Milwaukee called Growing Power that does some greenhouse heating with compost.  They also use large stores of water (for aquaponics) to help regulate air temps.  They're worth googling imo.

St. John's has a humid continental climate (Köppen Dfb) with cool-to-warm summers, and relatively mild winters, which is due to Gulf Stream moderation. Mean temperatures range from −5.4 °C (22.3 °F) in February to 15.5 °C (59.9 °F) in August, showing somewhat of a seasonal lag in the climate. The city is also one of the areas of the country most prone to tropical cyclone activity, as it is bordered by the Atlantic Ocean to the east, where tropical storms (and sometimes hurricanes) travel from this country.

Of major Canadian cities, St. John's is the foggiest (124 days),^[34] windiest (24.3 km/h (15.1 mph) average speed),^[35] and cloudiest (1,497 hours of sunshine).^[36] St. John's experiences milder temperatures during the winter season in comparison to other Canadian cities and has the mildest winter for a city outside of British Columbia.^[37]

Insulation seems to be key, along with the other ideas being present here. This makes me think that many of you just don't grow fig!!

I don't think I will have much trouble incinerating the plants here, but I could use a smaller solar furnace to account for that...I do not want to underestimate the heat that could be generated. And yes, for sure, putting that into some passive device (water and rock?) would be the ideal. This is great input. thanks. 

How about using windmill or geothermal energy and connect to radiant floor heating.

if you have more cloud and rain than anyone else, solar heating might not be a good choice. But if you go that route, and have the space for the black panels on your roof, the pool heating systems do produce a lot of heat. Then you need some sort of fan and heat exchanger in the greenhouse.

I do not know if anyone else got anything to add, feel free.

Looks like I have lots to check out! Thanks.