Recommend very hardy perennials
I'm looking for some very hardy perennials which can grow in demanding conditions. In winter, often -12C and quite wet for long periods, and in summer, 38-40C and very dry. Unlike everyone around us who have poor soil and grow plants for hot, dry conditions, we are in the bottom of a valley on good, alluvium soil, but the cold/wet kills most plants. The other constraint is I don't want any yellow or orange plants!
Here are some links that will help you make some selections.