I need advice

[Bernie]

This is my first winter with a greenhouse. My greenhouse is a green poly 4'w X 8'd x 8't. It is completely sealed except for the zipper entry door. I have it insulated with two layers of heavy bubble wrap that is much like a pool cover. The door way is protected from a rush of outside air coming in by a curtain of the same bubble wrap although there are large gaps at the top and bottom. There are no vents. In the spring I just opened the door when it got too warm but it wasn't freezing during the day. I can’t afford to run a heater but I kept it above freezing at night with only a few light bulbs even when the temp dropped to 19* without much drain on the power bill. There are plants growing in a wooden box raised bed in there that's 4' X 2' X 2' deep which I am sure helps.
Before long it will be below freezing for the duration of the fall and winter. This is an experiment. I know controlling the temp will be a challenge but since I am home 24/7 I will be here to monitor it. I know it will get to warm in there on sunny days but I’m not sure how to deal with that. Can I just open the door a little? It opens from the bottom. Or should I open it all the way and leave the curtain closed. I wouldn’t want to let the temp drop to low. Should I cover the whole thing with shade cloth? Would it work okay if I simply laid the shade cloth on top of the plastic greenhouse cover? How important is air circulation? Should I put a little fan in there? How long does it need to run? I have to keep the power bill in mind. Any and all help would be appreciated.
Bernie

[joclyn]

i would definitely put some kind of fan in there and leave it running constantly.

you could try opening the doorway a bit and leave the inside cover down - there's sure to be a bit of a breeze and that should be enough to move the inside covering just enough to cool it down if it gets too hot. although, it's not likely to get too hot if the outside temps are freezing or below.

i wouldn't think opening the doorway all the way would be good (even if you leave the inside cover down) as you'd be more likely to get a really cold blast into the gh and that wouldn't be good.

since you're home you can monitor things and adjust accordingly until you find what works best.

i don't think shadecloth would be a good idea at all in the winter - you want the sun to warm things up.

is there enough support on the roof area so that snow weight won't buckle the whole thing or break through?

keep us posted on how things are going!!

[Bernie]

Thanks Joclyn. Should I aim the fan at the plants or just let it circulate the air throughout the GH?

I don't know if it will hold up to a snow load. We don't get a lot of snow here most years so it's fingers crossed and hoping for the best.

This is an on going experiment so I don’t have any expensive plants in there. I started with a pile of junk, lots of research and picking the brains of everyone and anyone I thought could help. I got so many negative comments on another site; if I’d listened I would have never even tried it. I am a determined person so I didn’t let it deter me. I’m glad I chose to listen only to the positive folks because it worked even better then I hoped last spring. I have to keep my eye on the pocket book so it’s one step at a time. If I can control the temps and the plants survive I will stretch the budget and build a sturdier frame and roof next year. If not I will only use it in the spring to start cuttings etc. As they say nothing ventured nothing gained.
Thanks again,
Bernie

[joclyn]

nothing ventured; nothing gained. absolutely!!

i would just put the fan somewhere near the roof area so that it gets the air moving throughout. if you can put in a small ceiling fan, that would be ideal. if not, a small fan in a corner would do.

[Bernie]

Thanks again for the input.
:hug: Bernie

[Pennylee]

Bernie, I don't think you mentioned having a greenhouse thermometer?
There are all kinds, from very simple through to digital and they don't seem to
be extremely expensive. They would give you an optimum temperature to work from. You could use trial and error by cautiously switching on or off a certain number of heating globes for a limited time, and as it is entirely your
greenhouse you would gradually know what other controls to introduce.

Probably a simple vent or vents able to be opened or closed could be
incorporated into any plastic greenhouse, just as long as you had good advice that these items
worked and were trouble-free, including their installation! If you type "add vents to plastic greenhouse" for instance,
you are presented with some options.

[Bernie]

Thanks Penny I have two simple thermometers. Last spring I moved them to different areas of the GH looking of cold spots. That is how I learned I needed to add the curtain inside the door. Also found a few leaks that way.
I never thought to look up how to vent a plastic GH but that's a great suggestion so I will.
:hug: Bernie

[donybee]

My greenhouse is completely sealed for winter. I heat it with a Delonghi oil filled heater with a thermostat. If the sun is out the temps can get over 130+ degrees. If the sun is out I open the main door and a window directly across from the door and that usually brings the temp down. Just have to make sure you don't forget to close them back up before nightfall.:lol::lol:Our winter temps here can drop as low as 20 below so it has to be heated. I will start using the heater at night when temps go below 30 at night. Does your GH have a window you can open? If not a fan would work as well.

[Bernie]

Nope, no windows Dony. DS was over this AM and reminded me of a camping tent we had with windows that were just flaps that closed up with Velcro. I remember it but not precisely how it worked. I am going to experiment with some left over plastic and bubble wrap before I cut into my GH cover. I still haven’t found a fan but I’m sure I’ll find something before long. For now the temps during the day are still warm enough that I can open the door without worry.
:hug: Thanks for the input.
Bernie