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Those good old-fashioned blue flowers

Blue flowers create a sense of calm and peace. A completely blue summer border is particularly attractive; but from a design perspective, it’s important to include a few plants with silver foliage or soft white or yellow blooms.
Campanula cochleariifolia
Summer blues – Creeping or spiral bellflower (Campanula cochleariifolia)

Blue flowers create a sense of calm and peace. A completely blue summer border is particularly attractive; but from a design perspective, it’s important to include a few plants with silver foliage or soft white or yellow blooms. Otherwise, the blues may disappear into a seemingly black hole. Here are a few suggestions of old-fashioned blue flowers with the added advantage of drought-tolerance.

The Carpathian bellflower (Campanula carpatica) is dependable, long-lived, easy to grow from seed, and adaptable in use and habitat. The blue, up-facing flowers, 1 to 2 in. in diameter, bloom for a long period in midsummer. They are held above a neat compact mound (12 in. tall and wide) of dark green foliage. It grows equally well in full sun or partial shade on well-drained soil. Deadheading prolongs the blooming period. Carpathian bellflowers are ideal for the front of the border, the rock garden, and edging. ‘Blue Clips’ is a compact form with medium blue flowers; ‘Deep Blue Clips’ has dark violet blue flowers; and ‘White Clips’ is similar but with white flowers.  The newer Pearl series (in deep blue or white) is similar but with earlier flowering and slightly larger blooms.

Creeping or spiral bellflower (Campanula cochleariifolia) is a diminutive perennial and is a lot tougher than it looks. The bright green foliage, only 3 to 4 in. tall, is almost hidden by a myriad of tiny, outfacing, blue, bell-like flowers in June and July. It spreads by creeping rhizomes, soon forming a solid mat. Grow in sun or partial shade in well-drained soil. This is an excellent plant for edging, the rock garden, a groundcover, as a pavement planting, cascading over walls, in crevices, and on garden steps.  ‘Miranda’ is taller than the unimproved species, with larger, silver-blue, outfacing flowers while ‘Alba’ is a white form.

False indigo (aka wild blue indigo (Baptisia australis)) has deep blue pea-like flowers, blooms in May and June, and somewhat resembles lupin (Lupinus perennis). The inflated seedpods are black, curled and decorative. It tops out at 3 ft. with an arching, upright form. The trifoliate blue-green leaves are compound and remain attractive until hard frost. It is long-lived, with thick, strong roots. Plant in full sun on well-drained soil. It does not tolerate root disturbance once established. Use in the perennial or mixed border, as a specimen plant, and in a wild garden. Both the flowers and seedpods can be used in floral arrangements. In addition, it is a butterfly nectar plant. ‘Solar Flare’ is a new, largely untested cultivar worthy of trial. The flowers open lemon yellow, changing to a rusty orange blush as they age.

Another old-fashioned perennial, perennial cornflowers (Centaurea montana) have graced prairie gardens almost from the beginning of settlement. The large, globular, thistle-like blue flowers (1–2 in. diameter) with a reddish centre are held on 24 in. stems above grey-green foliage. They bloom profusely in June followed by less intensive flowering in July and August.  Grow in full sun or partial shade in most soils. They may spread beyond their allotted space and may require occasional containment with a sharp spade. Deadhead to prevent self-seeding. Because they self-sow and spread by stolon, perennial cornflowers are best used in an informal border or allowed to naturalize. They are used as cut flowers and are a butterfly and bee nectar source. ‘Alba’ is a white form while ‘Rosea’ is a pale pink form.

‘Amethyst Dream’ and ‘Amethyst in Snow’ are largely untested in the colder areas of the prairies but are worthy of trial. ‘Amethyst Dream’ is more amethyst in colour and 12 to 16 in. tall while ‘Amethyst in Snow’ is more compact with silver green foliage and its flower petals are white with a dark purple centre. The latter has overwintered in a friend’s garden in Saskatoon.

Sara Williams, author of the recently expanded and revised Creating the Prairie Xeriscape and with Hugh Skinner of Gardening Naturally, A Chemical-free handbook for the Prairies, will be offering several courses during HortWeek at the University of Saskatchewan, July 2-9, including “Xeriscape” and “Perennials, the Enduring and the Fleeting”. See http://gardening.usask.ca for these and many other courses, including free events.

This column is provided courtesy of the Saskatchewan Perennial Society (www.saskperennial.ca; hortscene@yahoo.com; www.facebook.com/saskperennial). Check out our Bulletin Board or Calendar for upcoming garden information sessions, workshops, tours and other events.

GardenLine is back for the season to help solve your gardening glitches. FREE. Phone (306) 966-5865 or email gardenline@usask.ca.