You don't want a severe temperature change to shock them. Once 45 degrees at night is happening, bring them in. Place in your sunniest spot where you can see the winter through together. They will need at least 4 hours of direct sun indoors to flourish. Let them rest by not feeding them very much and keep them on the dry side.
Some gardeners recommend cutting the plant back by a third before bringing it in.
Culinary Uses Cut leaves finely and use to flavor cakes, jellies, sauces, and even vinegars. Lay whole leaves under cakes where they will release their subtle flavoring. Toss the delicate flowers into salads. In terra cotta pots of all shapes and sizes or lining an entrance way, scented geraniums are stunning. If you keep them in pots they are much easier to remember to bring them in when the days get short.