Where can I learn more about how to garden on a ridge, solid rock and in part crumbling shale, in the Mid-Hudson Valley? Although close to the house, irrigation on it would be cumbersome. Tall oaks have grown and some still do grow on it. Also blackberries, reindeer moss, verbascum, rosa multiflora, and thyme grow spontaneously. It has been mostly clear for many years; a string trimmer goes over it twice a season. The sunniest part gets about eight hours a day. There is intense daily deer traffic. Tough roses have failed to thrive. Deer miniaturized a japanese maple. A Russian Olive flourishes. How should I prepare the site? A selective pressure hose? Alliums and other bulbs, irises, thermopsis would, I hope, grow well. The lists in books about xeriscaping are helpful but not focussed enough on the problems posed by this site. Any advice would be warmly welcomed.