True-blue garden flowers... and a few leaves

Blue of my heart
Blue of my dreams
Slow blue love
Of delphinium days

-from the Derek Jarman film Blue

True blue—not purple--- is a comparatively rare occurrence in the plant world. Perhaps it’s just this rarity that inspires blue garden enthusiasts. For others, symbolism may be important: blue flowers are variously held to symbolize, invoke, or instill serenity or stillness, remembrance, introspection or creative dreaming. A blue garden can be a meditative retreat, a private world. Or it could be a dramatic visual statement to harmonize or contrast with the color of your house.

Blues in the shade

You know the feeling: your pupils dilate, you are breathing shallowly, your heart pounds, and a wave of desire wells up, so powerful you feel you might swoon. Yes, you are in love again, and the object of your desire is… a plant. You are powerless, you must have it.

“It was like the Filene’s Basement wedding dress sale,” says the perennials buyer at a local nursery, explaining to me why all her Meconopsis x sheldonii have disappeared in a week.

Meconopsis x sheldonii is a hybrid of M. grandis and M. betonicifolia, two of several true-blue-flowered Meconopsis. The plants need shade, demand excellent drainage, and have a reputation for being very finicky and short-lived, but seem to do well here in the moist, mild Northwest. The 3-4 ft tall M. x sheldonii may be a little easier than others. The large, delicate, somewhat downward facing flowers are breathtaking.

Some Meconopsis are said to be monocarpic: the plant dies after flowering, but can produce offsets. Life of the parent plant and production of offsets can be enhanced by nipping off flower buds in the first season, so that plant energy goes into vegetative growth. Admittedly, this is a test of self-control that many may be unable or unwilling to endure. My advice: buy two plants, one for now and one for later.

Brunnera, one of several shade-loving Borage relatives, is a sort of perennial Forget-me-not: its flowers are intense mid-blue, in shape and size resembling Forget-me-nots. The leaves are large, handsome and slightly fuzzy, and the plant multiplies reliably, at least doubling its coverage every season. (The canny horticultural reader knows this means: give it some space, or be prepared to divide it and share the wealth.) Though spring is its main time to bloom and it is deciduous in cold winters, I’ve known Brunnera to stay green all winter long in a protected spot and bloom in a mild Northwest December. In recent years, several pricy cultivars (‘Jack Frost’, ‘Variegata’, ‘Looking Glass’, etc.) with variously white- or silver-mottled leaves, have been popular. I prefer the natural, green leafed species B. macrophylla. Be aware that some people report reversion in the cultivars to solid green within a few years, faster when the plant was divided or otherwise stressed.

Another Borage relative, the genus Mertensia (one of the many unrelated and diverse plants given the common name Bluebells) includes several striking perennials with small, bell-shaped, sky-blue flowers. A lovely and unusual species is M. maritima (syn M. parviflora) or the very similar M. simplicissima (syn M. asiatica): sprawling, low-growing plants with very glaucous (whitish, chalky), slightly fleshy leaves and sky-blue flowers. The plants are native to sandy seashores and are widely naturalized in coastal areas. Cultural recommendations vary enormously (sand or loam, sun or shade), but excellent drainage with regular moisture seems best, and at least some filtering of direct sunlight is desirable in inland locations with hot summers. The plant goes dormant and seems to disappear in winter, popping up again in spring. These Mertensias are not easy to find in nurseries in our region; I found M. simplicissima at Far Reaches Farm in Port Townsend.

Corydalis is a genus closely related to Dicentra (Bleeding Hearts), and likes similar conditions: moist, well-drained, lightly shaded- a woodland environment. Corydalis leaves somewhat resemble those of Dicentra, and plants bear terminal clusters of tubular flowers. Several cultivars of C. flexuosa are blue to violet. ‘Blue Panda’ has medium true-blue flowers. Foliage is winter-dormant and may go dormant in summer after blooming if conditions are too warm or dry. Perhaps the very bluest Corydalis is C. curviflora rosthornii ‘Blue Heron’, with intense blue flowers and very handsome blue-green foliage that is evergreen.

Ceratostigma plumbaginoides, False Plumbago, is a small, horizontally-spreading groundcover shrub that can be grown in sun or shade. It has attractive, glossy, mid-green foliage that is semi-evergreen in protected spots.  For me, it has been more deciduous, but one of its charms is that while the last of the flowers are blooming, the leaves begin to turn bright wine-red.  The flowers, appearing in late summer to fall, are about an inch across, five-petaled, and bright blue. Under favorable conditions, the plant will multiply via underground runners to produce an attractive, non-invasive ground cover. Hardy to zone 7, it should survive most winters in the Pacific Northwest. 


 A close relative to C. plumbaginoides is C. griffithii, Burmese Plumbago. This is a more erect, slightly taller (2-3 ft tall and wide) shrub. It has somewhat differently shaped leaves than its cousin- they are charming, a little rounded, glossy blue-green with thin red margins; new stems are also red. The flowers are slightly smaller than those of C. plumbaginoides, and a lighter sky-blue. Cut the slender stems back hard in winter to improve the next season’s form and flowering. It’s one zone more tender than C. plumbaginoides, and should be fine for coastal areas in the Northwest, but is deciduous. It can be happy in full sun or part shade; it seems to flower less freely in shade than C. plumbaginoides.

Sunny Blues

Most of the Gentians are blue, and blueness is so linked to this genus that the word “gentian” denotes a bright blue color. Most gentians like moist, loamy soil in full sun or part shade. Watch out for slugs: they seem surpassingly fond of the flower buds and leaves of these plants. Gentiana asclepiadea is called Willow Gentian because of the willow-like shape of its leaves and its arching stems. It’s a very hardy perennial 24-30” tall, often in a clump to 2 ft across, blooming mid-summer to fall. The flowers are sometimes purplish but often bright mid-blue to dark blue, 1.5-2” long, flaring, narrowly trumpet-shaped, two or three to an axil. Willow gentian is very cold-tolerant, and prefers not to be in direct hot sun; light shade or placement for morning or late afternoon sun is good. Another easy Gentian is Gentiana sino-ornata (Chinese Gentian), a creeping rock garden plant that spreads by runners and forms a mat of grassy leaves. A profusion of 3” long, upward-facing, royal-blue, trumpet-shaped flowers with white and purple striping on their undersides (visible in bud), appear in fall. The plant enjoys excellent drainage, full to partial sun and regular moisture. It requires acidic soil, and will be killed by lime, but is otherwise easy-going. Several gentians are available at Far Reaches Farm in Port Townsend.

The genus Salvia is large and varied, including the aromatic but non-showy culinary sages as well as a wide range of very showy ornamentals with flowers in red, white, pink, purple, and blue. Most ornamental Salvias are tender (or just plain finicky) perennials, a few true annuals. One of the most stunning cultivars and bluest of flowers anywhere is Salvia guaranitica ‘Black and Blue’, a tall, tender, short-lived perennial having deep blue petals and black sepals. It likes moderate sun and moisture, and might survive winter in our region with some protection. In southern gardens, it reaches a size of 5’ tall and 3’ wide; it may not exceed 3’ tall in more northerly zones.

The little-known Commelina tuberosa (Blue Spiderwort, Day Flower) bears inch-wide flowers in an arresting royal blue hue. The typical plant is low-growing, somewhat sprawling. The flowers are similar in shape to those of Commelina’s close relative, Tradescantia (the garden plant Spiderwort, and the house plant Wandering Jew). By the end of one season starting from seed, a tiny cluster of tubers like miniature Dahlia tubers can be found at the base of each plant. In our region these tubers may or may not survive the winter, but Commelina liberally self-seeds. The tubers may also be lifted and stored, like Dahlias. C. tuberosa includes or is closely related to a very similar but somewhat taller, more erect form, C. coelestis. I have found sources for these and other blue Commelina species online; plants may also be available via mail order.

Anagallis monellii, available in the annual sections of nurseries under various cultivar names (‘Skywalker’ etc.) is actually a tender perennial (USDA zone 8). The foliage is so undistinguished that the plant is easy to underestimate until seen healthy, established and blooming in the sunny or part-sunny garden. Its small stature and trailing habit also make it a prime choice for containers. The flowers open in sun, close up when it’s overcast (or when the plant is watered overhead). 
When Anagallis is in its prime, the dinky leaves are masked by a profusion of stunning, deep blue flowers—almost indigo—velvety, five-petaled, with deep violet centers. Short, with a somewhat sprawling habit, Anagallis works well for a regularly watered rock garden, or in a container. 
 The plant blooms from early summer well into fall; a bit of judicious deadheading late in the season may be desirable to extend blooming and limit legginess. The botanical name Anagallis comes from the Greek “causing to smile”, which is exactly what happens when people see this beauty in bloom. Happily, small, inexpensive starts are readily available in many garden centers; seeds are also widely available (or may be collected from the plant) and are easy to grow.

Iris cristata is a short rock garden iris with narrow, woody-looking rhizomes and flowers that may be pale to medium, occasionally deeper blue. It’s one of the earliest Iris to bloom and one of the bluest. Excellent drainage and regular watering through the spring and summer should keep it happy. The soft, pale green leaves go dormant in winter, so mark the plant’s location. In a felicitous spot, Iris cristata will multiply gradually, and it is extraordinarily winter-hardy. It’s an eastern North America native and I’ve never seen it in a nursery in the Northwest, but bareroot plants or rhizomes can be obtained via mail order.

Chionodoxa is a small bulb closely related to Scilla. Its common name is Glory of the Snow, because its small blue blooms, in most species borne on 3-6” stems, are among the first to appear in early spring. My favorite is C. sardensis, which has intense blue flowers with white centers. C. luciliae’s flowers are a lighter sky-blue. 
 The 19^th c Swiss botanist Edmond Boissier named it for his wife Lucile, who died from a disease contracted while accompanying him on a plant collecting trip. This tiny plant is lovely for a rock garden—or plant several in a large container, over other bulbs that will emerge later in the season. C. luciliae is increasingly available in the bagged bulb sections in stores; both C luciliae and C. sardensis can be obtained via mail order.

I first saw Nemophila menziesii, Baby Blue Eyes, in 1988 in coastal Mendocino, CA, among other wildflowers on a bluff overlooking a rocky beach where Harbor Seals lounged. Flowers, ocean, seals, blue sky, and my first time on a (terrifyingly tall) horse… Maybe it was the potent cocktail of endorphins and adrenaline, bliss and terror, but having survived the ride, I was in the grip of a new passion, for the beautiful sky-blue flowers with white centers freckled with tiny dark spots. 
 Short and short-lived, the west coast native annual Nemophila menziesii (syn. N. insignis) is distressingly all but unknown in the world of nursery six-packs, but can be found in many wildflower seed mixes, and in individual seed packets.

Eryngium (Sea Holly, Rattlesnake Master) has many species and cultivars. This otherworldly-looking plant belongs to the Carrot family, and bears thistle-like flower heads resembling the unrelated Echinops. Most Eryngiums are hardy perennials with grayish, prickly foliage, and like full to part sun, moderate moisture and good drainage. The different species vary in height from 2-6 feet tall, and flower color may be silvery or greenish or blue. Among the bluest are the drought-tolerant E. maritimum ‘Sapphire Blue’ (30” tall) and E. alpinum ‘Blue Star’ (24” tall). Both need excellent drainage.

Clematis integrifolia- a species clematis (not hybrid), has nodding, trumpet-shaped, soft mid-blue flowers, followed by the fluffy seedheads typical of the genus. It grows as a somewhat relaxed, upright, delicate and airy deciduous shrub 2-3 ft tall, (not a vine) and needs no support. Numerous cultivars (selected strains) of the species are sold as well, differing most notably in their range of flower colors. Unlike the hybrids, species clematis are also fairly easy to grow from seed. Growing conditions are the same as for other clematis- filtered or full sun with shaded feet. C integrifolia is a summer bloomer, and so falls into Clematis pruning group “3”, which can be pruned hard in late winter or early spring.

No garden is complete without a couple of weeds. Really… and no account of blue flowers is complete without mention of Chicory (Cichorium intybus). Yes, the old-fashioned coffee substitute (its root, roasted and ground up) and common roadside weed. With sky-blue, daisy-like flowers, this perennial plant is a delightful mid-summer-to-fall visitor to fields and the wilder reaches of a yard, or a spacious cottage garden (if you don’t mind a bit of unruliness). In addition to the roots, the leaves are edible; the species is the source of both Radicchio and Belgian Endive. Escarole, also sometimes called (French) Endive, comes from the closely related annual Cichorium endivia. If Chicory is too weedy-looking for your ornamental garden, consider including it in a patch of edible landscaping.

Blue is characteristic of some plant families more than others; a wonderfully comprehensive list of families and genera can be found in Robert Geneve’s Blue Flowers (Timber Press, Portland, OR, 2000). Profiles of numerous blue species and genera are provided. A perhaps minor cavil, though disconcerting: I find that the color plates with which the book is generously illustrated- perhaps as an artifact of the printing process-- portray many flowers as more purple (as opposed to true-blue) than they are in life.

Blue foliage

Variations on the blue flower garden can include working with foliage color. For blue leaves, the standards are: Hosta (several cultivars, including ‘Abiqua Drinking Gourd’, ‘Krossa Regal’, ‘Blue Heaven’, ‘Blue Jay’, ‘Blue Mammoth’, ‘Blue Umbrellas’, and ‘Blue Mouse Ears’!); the grass Festuca glauca (Blue Fescue) - several cultivars, most well known ‘Elijah Blue’; Blue Fountain Bamboo (Fargesia nitida, a clumping species); Blue Oat Grass (Helictotrichon sempervirens); Carex glauca (Blue Sedge). For shrubs and trees in the blue range, consider Blue Willow; several species and varieties bear this common name, including Salix purpurea and its botanical varieties and cultivars. There are also numerous conifer genera that include blue species or cultivars, notably Juniper, Cedrus (Cedar), and Picea (spruce).

Blue flowers, gold leaves

Another choice for foliage color is contrast of blue flowers with gold leaves. Caryopteris ‘Worcester Gold’ is a shrub with sky-blue flowers and gold leaves; Sunshine Blue has deeper blue flowers. Ceanothus is a genus of mostly tall shrubs, many of which have deep to light blue flowers. C. griseus var. horizontalis ‘Diamond Heights’ is a very low-growing rock garden plant with striking green-and-gold variegated leaves and light blue flowers. Corydalis flexuosa ‘Golden Panda’ has sky-blue flowers contrasting with foliage that turns chartreuse-gold. Golden Rain Rosemary, Rosmarinus officinalis cv Joyce de Baggio is an upright, rather tender variety with leaves that are gold in spring and fall, sometimes described as variegated, and with pale to mid- blue flowers. Ceratostigma x willmottianum ‘My Love’ PPAF is a short, erect shrub with sky blue flowers and gold leaves.

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A few genera with blue flowered species*

Aconitum

Agapanthus

Agastache

Ajuga

Anagallis

Anchusa

Brachycome

Brunnera

Caryopteris

Ceanothus

Centaurea

Ceratostigma

Chionodoxa

Cichorium

Clematis

Collinsia

Commelina

Delphinium

Echinops

Echium

Eryngium

Gentiana

Hyssopus

Iris

Linum

Lithodora

Nemophila

Nepeta

Nierembergia

Nigella

Omphalodes

Passiflora

Perovskia

Polemonium

Pulmonaria

Rosmarinus

Salvia

Sisyrinchium

Vitex

Wulfenia

*indebted to a more comprehensive list in Robert Geneve’s Blue Flowers