Hello larrym
I live in the Lothian region of Scotland at a height of 1000 feet. This year we have had a few frosts quite mild but bad enough to kill Pellies. In my experience there are two options
1) Put a heater one of your cold frames that will maintain a minimum temperature of +5 degrees Celsius.
2) Take cuttings from your plants in early Autumn, you may wish to spray your plants against fungal diseases and pest infestation. Insert the cuttings without rooting hormone into good quality general purpose compost containing about one third of volume vermiculite, perlite or coarse sand, water and allow to drain. Place the pots on a well lit window sill in a frost free environment. This is the method I use, you should put about 5 cuttings per 5" half pot. NB Do NOT tent, or close up your cuttings. Also take care if using non peat based composts as some of the other materials, coir, bark etc.) retain too much moisture for pelargoniums, if you object to using peat try JI No1 soil based compost.

Many thanks for your helpful post! I do have a conservatory, and I am sure that it usually is above +5C in the depths of winter, so I wreckon this would be the best place to keep them, although it does face North.

I have just obtained ten plants of different varieties of Ivy Leaved Geranium for my hanging baskets, as I forgot to order seeds for them!

I have plenty of Pelargonium hortum which I raised from seed, but early dementia must be setting in.

Again thanks a lot for your help!

Larry