This depends on if they are true Geraniums, members of the genus Geranium, or the bedding/pot plants that are still erroneously called such but are really the closely related sub-shrubby Pelargonium's?

I'm guessing Pelargonium. Unless really leggy, lift indoors and take tip cuttings in spring.

I've taken mine into the greenhouse today Guest.........took off dead leaves and flowers and then found there were plantlets round the main stem. I seperated them and have planted the lot in a large pot with compost and grit. Will keep it fairly dry and wrap the pots in bubble wrap when it gets colder.