What is the maximum planting depth for dahlias?
I read recently on GardenWeb that some people in colder zones have been able to get dahlias to overwinter in the ground with extra protection like heavy mulch or strategic microclimate placement. What I'm wondering is whether or not I can gain some extra protection by planting them deeper. So does anyone know what the maximum planting depth is for Dahlias? Could I plant them as deep as 12 inches? I learned last summer that callas can be planted as much as 12 inches deep for extra protection. Also would it help to cover them for the winter with sheet plastic to help keep them dry?