Caution: Be aware greenhouses are kinda like a disease that spreads- I started with one structure 20 years ago- now we cover 200,000 sq. ft. and ship nationally. Best wishes!

I am also in Colorado - moved here 2 years ago at 8000 feet, and have a an 8x12 Solex greenhouse which I don't heat at night either, although I do have a small heater for use on the occasional cloudy winter day we get. I use my unheated greenhouse nearly yearround - my plants spend the daylight hours in the greenhouse even in winter and then I just bring them into the house or garage (which is heated) for the night. I also have a 4-season sunroom in my home which is heated to use at night for plants. Springtime in my greenhouse starts around mid January - that's when the sun is bright enough to bring my geraniums into bloom when they spend days out there. Your greenhouse looks and sounds great, and with the magic of Colorado sunshine you may just find that you use it for a longer season that you expect! Between my greenhouse and my sunroom (which I just added onto my home last fall), I hope to be able to grow flowers and veggies yearround. Since you've got a fishtank, I was wondering whether you got the idea from the Growing Spaces Growing Dome - I would love one of those - maybe next time.

Dorothy

No, the I found the 100 gallon tank basically free at a garage sale, and figured I'd just throw it in under my workbench for thermal mass. Then it occurred to me that maybe I could raise Tilapia in it? I'd probably have to heat it with some large aquarium heaters, but then the heat just escapes into the greenhouse right? We'll see how that goes...

New question for everyone: I'm realizing now that I did not account for heat/air circulation within the greenhouse (when the vents are closed) and what a temp difference there is between the peak and the ground - I need to pull that heat down somehow. I don't really want to take up valuable roof space (I'm planning on hanging plants) with a large ceiling or even rotating fan for circulation, so my plan is this: Run a couple 6-inch round ducts/PVC pipes along the rafters, from the peak down to the ground on the opposite side (single-sloped roof - see pic link), and install inline duct fans in each to suck the air from the peak down. With each inline fan rated at 160 CFM (320 CFM total), and a greenhouse size of 1536 CF, this should circulate the entire structure in about 5 minutes (in theory). One day I'd like to perhaps dig out my planting beds and install a base of rock/gravel and run the heated air through that to better store heat, but that's not this year...

Questions:

1) Where along the ducts/pipes is the optimal place to install the inline fans? Top (pushing air down), bottom (pulling air down) or middle?

2) I've thought it might be nice to instead of simply having an open end at each duct/pipe that simply draws and exhausts air at a single point, that it might be better to install a perpendicular pipe at each end, that ran the length of the greenhouse, and was drilled with large holes that would more evenly draw and exhaust the air. However, will this create to much airflow "resistance", and dramatically reduce the circulation rate? I suppose I could always up the duct/pipe size and fans to compensate, but you gotta draw a line somewhere...

3) Anyone ever done anything like this?

Here is a link that might be useful: Greenhouse Photos

i have lower intake fan and higher exhaust fan and both are temp. controlled. i figured how much cubic air space and bought the fans that moved that much air per minute.

I would not go with upside down plants - first you are talking about a significant amount of weight; secondly, they will block important light from reaching plants below it; and third, very few people have lots of luck with them - the soil dries quickly or gets too hot, especially in summer.

My GH is also 12x16 but only 8.5' high, sloping to 5.5. I have a total of 1650 watts of electric heaters and as long as the temps stay above 20 degrees or so, my GH stays in the lower 50s or higher. I did buy a used kerosene heater but have only spent about $30 on kerosene this year, and almost all of that has been since early January. Next year, I plan on using it for live growing until mid December then will close most of it off and use just the front to overwinter bananas, coffee, pepper and cotton plants. Simply not enough sun light from mid-December to early March.

You'll love it, though. But unless you will be able to babysit it during the day, be sure to have the heaters and vents operated by a thermostat. I've seen the outside temps be five degrees at 7 am with a GH temp of 55. Four hours later, even after turning off the kerosene heater, it can easily be 105 inside.

Mike