GH ventilation.

[Cheerypeabrain]

I have a cold GH and CF, I've got quite a lot of plants holidaying in them over the winter. Last year most things were OK but I lost some tuberous stuff like chocolate cosmos and dahlias when they got attacked by mold. This year I've tried to space things out so that air can circulate around them, but I read that I need to ventilate as well. How often and when ?...I'd be grateful of any advice.
I've also read about making a makeshift heater using a big clay pot full of sand, popping a lighted candle in it then putting another (empty) clay pot upside down over the top...anyone tried this? Generally my moosa and tree ferns etc have been OK with just the protection of the GH.
thanks
CPBx

[Deleted]

I can see a problem with the candle in pots idea, you must make sure that air can circulate through the pots for the flame to stay alight. It would be a very expensive way to heat the air.

I would suggest a cheaper way (if no electricity is available) is to use a Chalwyn Tropic Hurricane Lamp (cost about £12 and the most reliable make), set the flame at a moderate level and it will keep frost at bay, giving up to 24hrs heat on 1/2 pint of paraffin (about 35p).

If electricity is available then a thermostatic fan heater with anti-frost setting (about £20) might be cheaper as it will only switch on when needed.
It will also circulate the air preventing hot and cold spots.

[4pygmies]

I don't think you need to worry too much about keeping things warm CPB and ventilation is really just common sense stuff. I think most plants can cope with lower temperatures than you might expect as long they aren't exposed to very cold for very long. Damp will kill things much more than cold. During the day unless it's really really cold is fine but not at night. I usually do any watering in the morning and leave the door open. People are always advised to wrap things that are very tender in bubble wrap but I think fleece is much better as it ventilates better so keeps the damp off. It's only in the really bitterly cold weather that I put fleece over plants in my unheated GH and PT. In emergencies newspaper is fine as a temporary cover too. X

[Cheerypeabrain]

Many thanks both x

[Chuckles]

I have my GH Bubble wrapped but only in the roof space, it's set up to work like a roller blind on both sides, I just roll it down when a frost is forecast. Also have 1"polystyrene sheets above the staging all the way round the GH. You do need to be careful with the bubble wrap as it does cause condensation between it and the glass, then you get the dreaded mould and that awful green slime builds up on your glass etc etc.

My window is always open and the door is fully open during the day and half open at night, only closed at night when it's -3 or below.

Dutchy got some polystyrene on a roll to line out her CF

Good Luck