How low can it go

BeeCee

I have pelargonium cuttings overwintering on windowsills in my house.  They are getting quite large and I need the space.  How low a temperature will they tolerate in an unheated greenhouse?  The nighttime temperatures have been around 4 or 5 but are forecast to go down to 1 degree later in the week.  

Penny_Forthem

Mine have been in an unheated greenhouse all winter and are all very perky!

Fairygirl

4 and 5 would be fine but they might be a bit vulnerable at that lower level. Technically below 3 is a danger of frost. 
Could you cut them back a little and keep them in your house a bit longer? Or give them some fleece protection in the greenhouse?

BeeCee

Thanks.  I'll use 3 as my working number.   I would hate to lose the pelargoniums after nursing them all winter.  It's probably only another week or two until things warm up.  

Fire

I find it does a bit depend on the pelly. Some I've had are quite tough and some will have one frost and they kick the bucket. Perhaps you can find what kind you have. Here in London, in sheltered spots, some people leave their toughies out over winter fine.

Fairygirl

I certainly couldn't leave them in a greenhouse here without additional heat