Lift or protect dahlia tubers
Protect your dahlia tubers from frost damage by digging them up or putting frost protection over them in the border. If you grow dahlias somewhere mild and sheltered in well-drained soil they will overwinter without damage, but, just to be sure, putting a thick mound of compost, leaves or bracken over the top will protect them.
If you think they won’t survive, lift the tubers, brush off the soil and bed them into a pot of loose compost. Pop them somewhere frost free and don’t water them until next spring.