To Lift or Not To Lift
As dahlias are not frost hardy, it’s normally best to lift and store tubers over winter. Once the first frost has blackened the foliage, with a fork, lift each tuber and brush the soil away from the roots. Cut back the stems and place upside down, allowing any moisture to drain away freely and naturally. Once dry, wrap in newspaper or pack them in dry sand or compost and place somewhere dry and frost free.
In warmer parts of the country, or areas which are particularly sheltered and if the soil is well-drained, it may be possible to leave tubers in the ground. A good layer of mulch, well-rotted manure, straw, or garden compost will help to protect tubers from light frosts.
