Well they're no more hardy than any other Pelargonium (common name geranium), so they will need protecting over winter, and you will likely need to cut them back, then introduce some heat, light, feed and water around March, under cover, to get them going ready for putting outside in late May again.

Thanks for that Bamboo it was very helpful

They stand the best chance in pretty dry soil, especially at lower temperatures. Cold and wet make them rot.

Thank you for your replies and help