Beth Chatto's Gravel Garden. Allium Nigrum and a very wide selection of allium bulbs in the UK, try Bloms. Cool colors in a hot garden: allium Nigrum is planted with veronica 'Kapitan', stachys byzantia, and a cristophii.
Beautiful blue perennials add a different kind of color to the landscape. Sedum cauticola is the small leaved plant. There are also Hens and Chicks, along with Blue Fescue grass. All are drought tolerant too!