What I start with: I know the shape of this plant. Perhaps from seeing it in nurseries, books, Kew or other gardens, I don’t know how. It has opposite leaves; each pair perpendicular to the one before, so to look down at a sprig it has a square silhouette. It has usually purple flowers and it is Hebe. Next I find out more:
Hebe (pronounced HEE-bee) is named for the Greek goddess of youth, who the Romans called Juventas.
Hebe, native to New Zealand, is sometimes called evergreen or shrubby veronica, though it is in the Scrophulariaceae family. Hebes range from petite mounding plants suitable for an alpine garden to tall shrubs. There are many cultivars with various flower color and leaf variegation. Hardiness varies, but is generally 8 to 11, the smaller types being more cold-tolerant. Butterflies like the flowers.
Plant in full sun to part shade in well-drained soil. Prune in early spring and pinch back after blooming. Hebe can be grown from cuttings taken in late summer. Hebe albicans ‘Red edge’ is, I think, the one in the garden I’m working on. There are several specimens in the existing rock garden along the sidewalk. The leaves are so precise and geometric, with the detail of the purple line around the edge of each blue-grey leaf. I just find them so attractive.
Much more about hebes can be found at the Hebe Society. http://www.hebesoc.vispa.com/