Too cold for them, particularly at the moment, possibly. Leave them out for short periods during the warmest bit of the day, bring back inside. Extend gradually the length of time you leave them out for, till by mid May, they're out all night.

Thanks. Never used a website like this before, but think its going to be addictive!

Hmm, know what you mean, I wrote a blog on just that subject towards the end of last year, lol

Hi Penner I suggest you look at my latest blog on perlargonium/geraniums overwintering of, in pots without a greenhouse. This May is so cold at night in London area that it is not safe yet to leave new plants unprotected. Plastic bag over, fleece, in garden shed, anything just to give that bit of protection