Christine I went on a garden tour yesterday which were 5 gardens that were in the National Hosta Society Convention tour two years ago. Be still my heart. Never saw anything like them before, not even on TV. Many of the gardeners double up a three gallon plastic pot (like the round black pots bushes and trees are in at a nursery) and plant the hosta in good soil with compost then sink the pot in the ground. When I asked whey they did it they said the hosta doesn't have to compete with the trees for water and the voles can't get to the roots in the pot. Maybe a tip that would work for you.
