These drought-tolerant perennials, Perovskia and Eryngium, make a great pairing for late summer sparkle, just when many border perennials are looking past their best. Grouping later summer performers together enhances their impact and helps create a focal point that can distract the eye from other, tired plantings. Although there are more striking Eryngiums, the species E. yuccafolium, seen here, works particularly well with the linear form of the Perovskia bloom. Its round, silvery seedheads remain attractive long into winter. Pairings that rely on contrasts of texture will, in general, have a longer season of interest than those relying on bloom colour.