Multiple award-winner, Salvia nemorosa 'Caradonna' is a favorite of many gardeners for its unique, glowing dark purple stems and stunning, vertical spikes of rich, violet-blue flowers appearing in late spring or early summer. Very striking when in bloom, they last for weeks and bring strong color and form to the landscape. Drought tolerant and deer resistant, this Salvia is a real magnet for butterflies, hummingbirds and bees! Reliable and compact, it grows in round clumps of gray-green, aromatic foliage up to 18-24 in. high (45-60 cm) and nearly as wide.

If you love true blue flowers, do not overlook Anchusa azurea (Italian Bugloss). This pretty biennial or short-lived perennial forms loose clusters of tiny bright blue flowers, resembling those of forget-me-nots, on tall stems rising atop low clumps of large, deep green, hairy leaves. Blooming profusely for about 4 weeks in late spring to early summer, this Mediterranean native makes a beautiful background specimen for the sunny late spring border. Although short-lived, Anchusa azurea often self sows and remains present in the garden.

Adding a bold, vertical dimension to perennial flower beds, shade gardens, and cottage gardens, Digitalis purpurea (Common Foxglove) is a stately biennial or short-lived perennial boasting tall, one-sided spires of pendant, tubular, bright rosy-purple flowers, 2-3 in. long (5-7 cm), with white speckled throats. Blooming from early to midsummer, they rise from a basal rosette of downy, oblong, deep green leaves. Attractive to hummingbirds which hover near the tubular blossoms and to birds which flock to the seedheads in fall, this lovely plant naturalizes well, as it self-sows freely, and creates lovely colonies in the landscape.

A favorite of many gardeners, multiple award-winner Allium hollandicum 'Purple Sensation' is a striking ornamental onion with perfectly round flowerheads, 3 in. wide (8 cm), packed with dozens of small, star-shaped, rich violet-lilac flowers. They are borne atop sturdy stalks, which arise from a group of 6 to 8 handsome, blue-green leaves. Blooming in late spring to early summer, this spectacular Allium enjoys long-lasting blooms and makes outstanding cut flowers that will last for 2 weeks.

Compact and beautiful, Lavandula stoechas 'Anouk' features dark plum flower heads topped with long-lasting violet-blue bracts delicately fading to pink as they mature. Highly aromatic silvery foliage. Great for mass planting, low hedges, or containers. This French Lavender blooms almost continuously from mid-late spring to late summer.

A very desirable garden plant, Cirsium rivulare 'Atropurpureum', commonly known as Plume Thistle, is a tall, branching, upright perennial exhibiting strong, leafless stems with pincushion-like, deep crimson flowers, up to 1 in wide (3 cm), atop a large basal rosette of soft green leaves. A magnet for bees and birds! Blooming from mid-summer to late summer, Plume Thistle is a statuesque plant that slowly grows in clumps, up to 4 ft. tall (120 cm), and spreads 2 ft. (60 cm).

Forming dense, spreading mounds of neatly cut leaves, Geranium himalayense, commonly known as Lilac Cranesbill, produces dainty, yet very large, cup-shaped flowers, elegantly borne on long stems, in shades of violet, indigo, and blue from early to mid-summer. Compact, its foliage remains attractive throughout the growing season and makes it useful as a low ground cover. Turning showy reddish-orange in fall, it creates a pretty contrast.

Hardy and reliable, Agastache 'Black Adder' (Giant Hyssop) is a charming herbaceous perennial boasting bottle-brush, terminal spikes, 6-8 in. long (15-20 cm), packed with fragrant, tubular, two-lipped red-violet flowers emerging from dark buds. Blooming from mid-summer to fall, they provide a remarkably long floral display and add color as well as a lovely spiky texture to the garden.