poly greenhouse

I bought one of these (5x5 feet) to get me an early start next spring.
personally I dont like it as there is no ventilation but will make do until I can build something better maybe next summer.
One problem so far is I dug out a few geraniums from the garden and put them in pots, with some recent frosty weather I have kept the greenhouse closed and have noticed the stems are turning mouldy.

Is this ok or should I put the pots outside and just place in the greenhouse if freezing conditions are forecast?

 

You need to keep geraniums,(pelargoniums) a bit on the dry side during winter.
Make sure you remove any dying leaves regularly.

If your poly greenhouse has a door, which I presume it has, it might be good to leave it open in mild spells when no strong winds are forecast.

 

That is what I have been trying to do but we had a week of frosty weather and then some blustery winds so the tunnel was shut for the best part of 2 weeks.
I think it is going to be difficult to get a balance over winter, I noticed in the minus temp there was a lot of condensation inside that persisted all day.

 

Condensation will persist from day today, its part of our damp climate.
Dampness can be more of a killer than the actual cold.

You can only do your best and ventilate when ever you get the chance.