These unthirsty succulents, flowers, and grasses will thrive with little care — even on a roof
In the Southwest, swap in Agastache rugosa (shown) for Lavandula multifida.
Agastache rugosa: Stems of glossy green, licorice-scented leaves reach 5 feet tall and 2 feet wide. This perennial from Korea has purple-blue summer flowers that hummingbirds love. Zones 4–24.