If you mean hardy geraniums then yes.

Hi, welcome to GoY, if you mean Pelargonium, commonly known as bedding geraniums, then yes you can, if you pot them up, and put them in a greenhouse, you may get some flowers for a few weeks, but they are not hardy, if you want to keep them for next year, then it would have been better to take cuttings in august, because this years plants will probably get a bit leggy, but whatever you do, if you want to keep them going, you will have to heat your greenhouse, which is going to be more expensive than buying new plants next year, unless of course you want hundreds of them :-) Derek.

You don,t say where you live.I live in Hampshire and have several bedding geraniums , some in containers with conifers and some in the border, which have all survived perfectly after being left out from last year.All I did was when they started to look leggy and before Jack Frost laid claim to them,was to cut them right back and left them where they were.I have two containers of trailing ones which I will do the same with.If you have a sheltered corner in your garden give it a go.Some aspects of gardening come through experience, others by accident,kerryvw.

I overwinter mine in their pots in a cold greenhouse, cutting them back and letting them more or less dry out until early spring. It is mild here, though. Last winter, a few just kept flowering, including two I'd left outside.