Verbascum phoeniceum ‘Violetta’ – A seed strain of Purple Mullein which bears tall spires of deep violet blooms from May to July, when deadheaded. It is considered a short-lived perennial or a self-seeding biennial and has a basal rosette of deep green leaves. They prefer full sun exposures with sharp soil drainage. Grows 30″ high by 18″ wide. Hardy to zone 4.
Iris sibirica ‘Ruffled Velvet’ – Siberian Iris are versatile perennials that tolerate partial shade and will thrive in wet soils. ‘Ruffled Velvet’ features velvety dark purple flowers (from May to June) with a contrasting white throat and make good cut flowers. These should be divided in the fall, when the clump hollows out in the middle. Grows 24-30″ high by 18-24″. Z3.
Geranium platypetalum – A very beautiful species native to Iran, Turkey and the Caucasus. It bears large (1.25 to 1.75 inches wide) five-petaled blooms of deep violet-blue with dark purple veining. These are borne from early to midsummer over mounds of deeply divided mid green leaves. Makes a good flowering groundcover. Grows 12-18″ high by 18″ wide. Hardy to zone 3.
Aster tongolensis ‘Wartburg Star’ (syn. ‘Wartburgstern’) – For those of you who love fall asters but hate to wait until autumn, here’s one that starts blooming in early summer and continues through to fall. It bears large 2.25″ wide blooms of pale violet-blue with thin petals and contrasting bright yellow centers. Makes an excellent cut flower. Grows 24-30″ high by 15-18″ wide. Zone 4.
Aconitum napellus – The Common Monkshood gets its name from the tall spires of deep violet-blue hooded flowers that much resemble a monk’s cowl. These are borne from mid to late summer on plants that are often mistaken for delphinium. All parts of Monkshood are toxic and may cause harm by skin contact. Part Sun. Grows 2-4′ high by 12-18″ wide. Zone 3.