I have just taken my cannas into a frost free greenhouse for the winter. They are in containers. The greenhouse is very small and I would like to cut them back to make more room but I am receiving conflicting advice. Some say leave them to die down so the goodness goes back into the plant (like bulbs). Others say this doesn't matter as the frost would blacken the leaves anyway (like Dahlias). What do you do?
Watering also seems contentious. Some say they should be kept dry during the winter. However, Hart Canna who grow them commercially, say never let them dry out and water lightly throughout the winter.