Originally this was a stone quarry that had become overgrown by trees and chocked with silt. Our idea was a grotto, using the natural spring to make a pond with dense planting and stone paths up the steep sides: Zantedeschia aethiopica at the water’s edge, clumps of miscanthus peppered with pink echinacea and umbellifers, and swathes of ferns, foxgloves and verbena running alongside the steps.