With its deep purple leaves and pale blooms, Penstemon ‘Onyx and Pearls’ brings two very different colours to the same plant. The summer flowers have white centres and a soft lavender wash, standing out clearly against foliage that can look almost black.

Give this tall perennial space towards the middle or back of a sunny border. Its upright flowering stems add height above lower planting, while the dark leaves help break up larger areas of green. Try it alongside ornamental grasses for a loose, naturalistic effect, or pair it with white and blush-pink flowers for a quieter combination.

Even between flowering periods, the foliage gives the planting a distinct point of interest. Leave room around the plant so it can form a generous clump as it matures.