Unheated/uninsulated greenhouse - Page 2

For a few winters now we've bubble wrapped an aluminium GH using brown tape & a few pegs. Advice re ventilating is essential: just open the window & door during day time. Even doing that many years ago a heater still caused excessive/damaging moisture so I concluded our 6x6 GH too small, & not worth it.  I've not lost any plants over-wintering outdoors & GH as I've described.  INcidentally it would cost me a lot more to replace my plants than the price of online wrap & re-using plastic bags.  We also bought, very cheaply, horticultural fleece which is amazingly effective draped over outdoor plants, weighted down with bricks/stones.  All re-useable.

I have a large, wooden, unheated greenhouse. I pin bubble wrap along the northern side but bottom half only as I don't want to create too much condensation. I just lay loose fleece  on the plants if it's going to be especially cold. If it's going to be very cold I light a big "pillar candle" and stand it in a tin, on the floor, in the middle of the greenhouse ( cheap and effective). Don't forget, open the door when / if it's mild as condensation can be a big problem. 

just bought 30mts roll of bubble wrap cost 5.99. cheaper than buying plants next year. 

Thanks for the advice re insulating greenhouse with bubble wrap. Will def have a go and see what happens.

That reminds me- If you turn a large terracotta pot upside down you can light a tea light beneath. When it goes out the pottery still radiates heat, just like a storage radiator. Knowing how draughty my greenhouse is I dont need to ventilate, but yes take that into consideration.

Also filling several, preferably painted black, plastic bottles with water & placing around the greenhouse/coldframe. The water may freeze if very cold, but it acts as a 'heat exchanger' apparently & keeps the inside temperature more even. Am no engineer  but do still do this. J.

Thank you everyone. So many hints. i hope other gardeners find the hints useful as well 

I like the ideas for plastic bottles and upturned terracotta pots, plumstrudle. My greenhouse dosen't have an electric supply, and have shied away from oil heaters as I don't want to bother with an oil supply, so will try this. I wondered about a small solar panel; have not seen one marketed for greenhouses, though I did get a solar-powered water pump which worked well for 2 years then packed in. Though I guess if you don't insulate, these might all be a bit futile. Perhaps a double-glazed greenhouse............

Ginny May, I have seen 2 systems for solar panels for greenhouses, 1 at Hampton Court flower show last year and one (v. expensive) www.solarpvgreenhouse.com

Thanks, artjak, will look into them and maybe drop strong hints to Father Christmas!

Artjak it's my first year with a greenhouse as well, I have found all this info sooo helpful, Am now going to construct a warm area within greenhouse based on this info.

Let's hope it works 

Bjay

Ok - Put up mini greenhouse (found out its called a pot greenhouse) inside big greenhouse and put more tender plants in it raised up on some veg trays bought earlier. Have told OH he has to have soup tomorrow for lunch so that I have a tin to put a candle in. Have candles -they are chunky and were in the little bit of sun we had in the summer and melted and are misshapen so will use those for heat source only on coldest of days(nights). Feel well satisfied with that - now will just have to wait and see if it works

I think Jo you are really a mine of good sound economical gardening advice  Pat on the back

I have a couple of large sturdy coldframes- thanks for advice J, might use the tea light/pot and the black plastic bottles if it gets very cold.

Well the plastic bottle idea is down to a previous beeb board poster. Half of this yrs bottles are unpainted- oops, but better than none. No idea where I got the pot/tealight one though.J.

On looking for solar heating for greenhouses, I came across a suggestion for painting a lot of cans black and sticking them together as a heat harvester