I am on the middle of building this 10x12' greenhouse from Harbor Freight. There are quite a few opinions about this greenhouse available online. As I have not finished building mine I'll reserve comment. I have recently gotten nervous about overwintering my figs in it. I do have the auto opening vents so it should not get too hot. But I am worried about it getting too cold. I have 4 small heaters that I plan on setting with a thermostat. Possibly at 35 or 40 degrees. Will this be ok? I'm thinking the daylight hours should be fine and some heat will remain at night, but for 4-6 hours they may be very chilly. Can potted figs (1 year old 3 gallon mostly) withstand a frozen root ball should something go wrong? I also don't want to make it too warm so they never go dormant. Any advice???

This is not my greenhouse but the same kind.
I will repost on all of the modifications I will be making to it in a later post.
I'm in NJ zone 6b

  Thanks for asking all my same questions.
I have a 6X8 greenhouse on a covered porch with 2 sides exposed, facing South and West. 

Soni 

I just got done putting together the 6x8 from harbor freight it came out pretty good. I wish I would have went with the bigger one but oh well!!

Hello,
This is my first post so here it goes.
 Finished the same GH about a week ago in zone 6a MA. Glad a got the extra clips and about 10 tubes of silicone calk. Have 70 first year figs inside on red brick floor. Insulated the steel c-beam that is on 4x6 pt wood. Temps have run up to the low 90's. Running a small oil filled heater at night with small fan above and figs seem alright and have not dropped any leaves. Humidity is still very high and a work in progress.
Richard

Cool Richard, I have about 150 figs I need to jam in there. I will wait until they all go dormant before I do so. Maybe next year I will try to extend the season with a few varieties that will likely ripen with a few more weeks of warm weather. I have mine on 6x6 posts and plan on building benches that I will bolt onto the 6x6 and the frame of the Greenhouse. I am concerned about the minimum and maximum winter temps. I would not want to freeze them to death or have it too warm to break dormancy too early. I would not want to lose all those figs.

I have had a 6x8 glass greenhouse for the last couple years and find that at night the temp inside the greenhouse and outdoors is almost the same within a couple degrees . There is almost no insulation factor with the 1/8 inch glass . The cost to heat this thing would be ridiculous in the dead of winter ( zone 5-6) , so I only use it in spring and fall with a 1500 watt heater . I don't put anything in it when temps are -5c or colder , too costly . I store everything either in my garage , or Figloo with a couple light bulbs for heat .

http://figs4funforum.websitetoolbox.com/post/figloo-update-5040799?highlight=figloo

I'll be looking to add some water drums for more solar heat mass and will watch temp closely to see how this well insulated HFGH holds up to heat loss.

Google - HFGH 10x12. blogspot.com (found very helpful) and Anti-dust tape on e-bay.
 Richard

do figs require dormancy? what would happen if they were placed in the greenhouse before dormancy?  Some do grow figs in tropical locations.

Most need 100 hours of accumulated dormancy. If not they will be less productive. ( So I've heard). What I would not want is the cycle of dormant to breaking dormancy over and over again all winter. I just want a constant steady chill, but not too cold. I think I will be ok with small heaters set to about 35 degrees.

Hi, everybody. I have posted about my old scrap wood greenhouse before but I had a 6X8 greenhouse made of scrap wood and covered with 6mil builders plastic for years. Had to replace the plastic each year but I heated it with 2 inexpensive ceramic heaters from Walmart. I kept one on a thermostat set at about 38 degrees and only used the second one if the temp was going to drop into the teens. I used it for at least 10 years. Now I have a 12X24 hoophouse also covered in plastic but it is greenhouse plastic. In one half I have added a second layer of builders plastic with an air space in between the plastic layers and use 1 ceramic heater. I couldn't tell any difference in my heating bill with this greenhouse. My old greenhouse may have cost a lot to run the heat but I don't remember it being a big deal. But that second layer of plastic really makes a difference. Last winter I would go out at night and it would be really cold out, like down in the teens, and the heater wouldn't even be running.

I recommend a "i heater". Mine never will burn if you touch it on the vents, but will heat a 13'/13' room in maybe 30-40 (as long as all doors and vents are closed in the GH) minutes evenly. The box say a penny a day of electricity.

Hope this helps...

http://figs4funforum.websitetoolbox.com/post/need-advice-opinions-and-suggestions-for-greenhouse-6016689