Grecian horehound

A compact, mounding deciduous shrub bred in the 1930s by crossing the East Asian species Caryopteris incana (southern China, Taiwan, Korea, Japan) and C. mongholica (Siberia, Mongolia, northern China) - it has no wild range of its own. Its defining virtue is a flush of vivid blue-to-violet flowers on the current year's growth in late summer and early fall, a period when little else in the garden blooms, combined with aromatic gray-green foliage and exceptional drought tolerance once established. The honest catch is its borderline hardiness at the cold edge of its range: in zones 5–6 the woody stems routinely die to the ground in winter and the plant resprouts from the base each spring, behaving more like an herbaceous perennial than a shrub - gardeners in those zones should hold back pruning until new growth confirms the crown has survived.

An old garden-favorite annual native to Mexico, grown for showy daisy-like flowers in nearly every color but true blue - red, yellow, orange, pink, rose, lavender, green, and white. Bushy, leafy plants rise on upright, hairy, branching stems and bloom continuously from early summer to frost. A magnet for butterflies and hummingbirds, and one of the most reliable cut-and-come-again cutting-garden flowers.

Cheddar pink is a low, mat-forming evergreen perennial pink (a Dianthus, not a true carnation) native to calcareous rock ledges and cliff faces across western and central Europe, from the protected population at Cheddar Gorge in England east to Ukraine. Its intensely clove-scented, fringed rose-pink flowers and blue-grey foliage make it one of the finest front-of-border edging plants in a sunny, sharply drained garden. The honest catch is drainage: in any soil that holds winter moisture the crown rots reliably, so it fails in heavy clay or irrigated beds and thrives only where drainage is sharp and the site stays dry underfoot in cold months.

A low, mat-forming member of the mustard family from the Mediterranean coast, grown almost everywhere as a cool-season annual for its dense mounds of tiny, sweetly fragrant white four-petaled flowers. The flowering is so profuse it often hides the gray-green foliage entirely. It thrives in cool weather, tolerates dry soil and drought, and is a reliable nectar source for small pollinators.