I forgot, Aberdeen gets more rain than Durham.
Even so - my Heps and corydalis are in a bed raised about 4 inches of the path with board edging. Theres a birch in the middle. The plants don't touch each other so there's no real cover for beasties. The bed was backfiled with old soil based compost and lealfmould.
Its worked for the last two years.
Gerry