Mixed fountain grasses plus pee gee hydrangea, white echinacea ("White Swan"), plus possibly some oak leaf or Annabelle, plus possibly low white carpet rose. Maybe add Icicle White Veronica or similar. Do Russian sage and grasses near steps.
Lysimachia 'Beaujolias' and Aquilegia in purple themed border - The Brewer Dolphin Garden, designer Matthew Childs - RHS Chelsea Flower Show 2014 - Image No: 0458439 - GAP Gardens, garden and plant stock photography
A New Book Calls for a Revolution in Garden Design