Posted: 28/10/2016 at 18:03
I'm in Devon, too, and have lifted my dahlias today to be stored overwinter. In the past, in even warmer Somerset, I have gone down the "leave & mulch" route, but have found that they can still be vulnerable to the cold and, as Hosta has said, the wet of winter.
Once the tubers have drained and dried, I shall wrap them in newspaper and store until next spring. It works for me, and the plants don't become too large for their space, which they can otherwise do. It is easy to split the tubers to make extra plants, too.
I hated cutting out the flowers when they were still giving me so much colour in the garden, but some of the leaves had been blackened by the bit of early frost we had recently.
On the plus side, I now have two vases of colour indoors!