This is brilliant. I have just kicked three pots of hardy geraniums halfway across the garden because they died over winter altho going into winter perfectly healthy. I left the pots above ground in the cold frame (Zone 6) and despite a mild winter, I suspect the bitter cold we had in December froze them solid and then the mild wet winter rotted them. I bet if they had been below ground none of this would have happened. THANKS for this great information!