I know they can bloom every day of the year when the weather is mild, as often where I am in Ireland. Pelargoniums of all types bloom outdoors here too and survive the winter usually. A lovely lady from the Isle of Wight sent me a vinca many years ago which blooms right through the year all over the garden. In cold weather the flowers are white, but change to blue as it gets warmer. I think it is Vinca difformis, and can be seen all over my area of Wicklow, having come from gifts I gave to friends and acquaintances. Some people have begun to call it 'Star of Bethlehem'. It does climb but likes to grow in evergreen clumps also.