Blue in the Shade

• By Susan Martin
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• April 2018 - Vol.4 No. 4
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• 3 Comments

Studies have consistently shown that blue is the most preferred color the world over. Based on a 30,000 person survey in 2017 canvassing 100 countries, the world’s favorite color was declared to be a particular shade of greenish-blue. In the garden, blue blends pleasingly with different shades of green foliage and can be used effectively in combination with both warm and cool hues.

Although there are many sun-loving blue flowers, it is not as easy to find blue flowers that thrive in shade. The Boraginaceae (borage) family, however, gives us several beauties, four of which are described below. In addition to their striking blue color and shade tolerance, these plants are deer and rabbit resistant as well!  

FORGET-ME-NOT

Myosotis sylvatica: Meneerke bloem, Wikimedia Commons

Myosotis, commonly called forget-me-not, has a beautiful sky-blue flower. Native to Europe, this perennial can also be found throughout eastern and western North America, where it is an introduced species. It grows in many types of habitat, including disturbed areas such as roadsides. It flourishes in organically–rich, consistently moist-to-wet soils in full sun to part shade. In fact, this plant grows so easily that it is sometimes considered invasive. M. scorpiodes spreads by creeping roots, but will also self-seed. The common forget-me-not of borders and woodland gardens is M. sylvatica. Although technically a short-lived perennial, this plant is often grown as a biennial by planting seed in the ground in mid-summer for bloom the following year. It is also often grown as an annual by starting seed indoors about 8-10 weeks before the last spring frost date for bloom the same year. Forget-me-not is sometimes subject to mildew and rust. Although this plant offers a beautiful blue, those who want a plant that is not potentially invasive might consider the perennial, Brunnera macrophylla, commonly called false forget-me-not.

BRUNNERA

Brunnera macrophylla is commonly called Siberian bugloss or, because of its small forget-me-not flowers of light blue with yellow centers, false forget-me-not. The blooms appear in April to May in airy, branched racemes rising well above the foliage on slender stems to 18″tall. The perennial is primarily grown in shady areas for its attractive heart-shaped, dark green, basal foliage. The basal leaves form a foliage mound  (1.0’-1.5’ by 1.5’-2.5’) which remains attractive throughout the growing season. Smaller upper leaves are elliptic.

Brunnera macrophylla:Vauban at Polish Wikipedia

B. macrophylla grows easily in average, medium moist, well-drained soil in part shade. The plant prefers cool summers and grows best in USDA Zones 3-7. In Virginia, it needs to be protected from bright sun and does best in part-shade or filtered sunlight. Clumps slowly spread by creeping rhizomes, persistent underground stems that store energy collected during the plant’s brief growing season. Plants may self-seed in optimum growing conditions, but seedlings of variegated forms may not come true (may lose variegation). Remove ragged foliage in late fall and snip off the spent flower stalks in early summer to keep this plant looking its best. Divide plants in spring or start seeds in a cold frame in early spring. Slugs and snails can sometimes be a problem.

Brunnera Cultivars

• ‘Jack Frost’ grows in a mound (1.0’-1.5’ by 1.0’-1.5’). Its distinctive silvery white leaves have green primary and secondary veins and a thin green rim around the leaf edges. Its bright blue forget-me-not flowers add dazzle to the garden in spring, and the silvery leaf sheen continues to brighten shaded spots throughout the season. This cultivar is the 2012 Perennial Plant Association’s Plant of the Year and is prized for its improved tolerance of heat and sun.
• ‘Looking Glass’ is a sport of the cultivar B. macrophylla ‘Jack Frost’ and grows to a little more than a foot tall and almost as wide. ‘Looking Glass’ is distinguished from ‘Jack Frost’ by having less green-veining on its heart-shaped leaves as they mature to an almost glowing silver color. Delicate blue flowers emerge in spring. Drought tolerant once established, this cultivar requires little watering and is fairly resistant to pests.

B. macrophylla ‘Looking Glass’: Terranova Nurseries

LUNGWORT

Another beautiful spring bloomer that thrives in shade to part-shade is Pulmonaria, commonly called lungwort. This plant has been christened with a variety of other colorful names including: Bethlehem sage, Jerusalem cow lip, spotted dog, and soldiers and sailors. Hailing from a native range encompassing much of Europe and into Russia, lungwort is sensitive to toxins, and so is typically found in unpolluted areas. Lungworts are promiscuous plants that self-pollinate and hybridize. As a result, there are many named cultivars, often with little to tell them apart. Because so many similarities exist, extending to plants in the wild, botanists’ calculations of the number of species in existence vary from 12-18 species. P. officinalis  (the second word indicates medicinal use) has been one of the most commonly used species  in cottage gardens. Many of the newer hybrids exclude this species because it is so mildew-prone.

Pulmonaria officinalis: Pharoah Hound at the English language Wikipedia

The rough leaves, covered with hairy fuzz, are spotted, speckled, or blotched with silver. This striking coloration continues to add interest after the spring bloom has ended. Flower buds are usually pink, while the funnel-shaped flowers turn to blue, purple, pink, red or white after they mature, adding a flashy, two-toned color effect to the flower clusters. There are many newer cultivars and hybrids, such as ‘Apple Frost’ (rose-colored flowers that fade to violet-blue), ‘Trevi Fountain’ (large royal-blue flowers), and ‘Raspberry Splash’ (raspberry-pink flowers). Lungwort does best in shady or semi-shady conditions, requiring more moisture as the light increases. It tends to wilt in afternoon sun and may even go dormant during a drought. Ideally, it enjoys a moist, well-drained spot in the garden, with a little early morning sun but protection from hard, afternoon sun.  Amending the garden soil with compost increases moisture retention and improves plant growth. When happy, lungwort spreads easily through rhizomes. It will also self-seed, although as is typical of hybrid origins, seedlings are not always similar in appearance to the parents. Plants can be divided in early spring or in fall. The leaves attract slugs, who apparently don’t mind a little rough fuzz on their salad greens! Powdery mildew might also be a problem in hot, humid conditions. Cut off the flowers after they’re done blooming, and trim back the leaves as they begin to decline. It is good practice to dispose of the leaves rather than adding them to the compost heap due to their susceptibility to mildew. This pruning will help revive the plant as it flags in the heat of midsummer.

How did such a beautiful plant acquire such an unusual name? The genus Pulmonaria comes from the Latin word for lung, pulmo. In the 16^th century, a theory known as the Doctrine of Signatures purported that plants resembling certain human physical attributes were beneficial to the part of the body they resembled. This was a widely accepted theory, and people thought that the leaves of the lungwort resembled diseased lung tissue. The leaves were boiled like a tea and used to treat bronchial infections and pulmonary diseases.

VIRGINIA BLUEBELLS

Mertensia virginica, Virginia bluebells, is a hardy, early spring-flowering perennial native to North American moist woodlands. Other common names include: Virginia-cowslip, Roanoke-bells, and oysterleaf.

Mertensia virginica, Virginia Bluebells: Catie Drew

This erect, clump-forming plant grows 1-2’ tall and has delicate, terminal clusters of light pink buds that open to flared, trumpet-shaped blue flowers. As early as 1776, Thomas Jefferson noted in his garden book “a bluish colored, funnel-formed flower in lowgrounds in bloom.” The flowers contain five petals fused into a tube, five stamens, and a central pistil (carpel). The stamens and stigma are spaced too far apart for self-fertilization. The funnel-shaped flower attracts long-tongued bees, sphinx moths, butterflies and ruby-throated hummingbirds. Both the stems and the leaves of Virginia bluebells are smooth, while most borage family members have hairy leaves. The gray-green, oval, somewhat floppy leaves grow 6-8” long and die back to the ground when the woodlands start to leaf out. Because the plant goes dormant, it should be overplanted with annuals or used in conjunction with ferns and hostas and other shade-loving perennials that will expand as the growing season progresses.

Virginia bluebells grow and spread from rhizomes; the plants will also self-sow in spots where they are growing well. For introducing the plant in your garden, sow seed in either spring or fall, or plant nursery transplants in early spring. Plants can be divided after the leaves start to die back in the spring, or they  can be divided in fall if you remember to mark their location before they go dormant. As in their native habitat, they need a humus-rich soil, adequate moisture in spring, and sun before the trees leaf out. A dry habitat in summer suits them fine since they go dormant. Their fleshy rhizomes will rot in a poorly drained soil that stays boggy year-round. Although bluebells don’t attract rabbits, deer sometimes browse on the foliage. 

Hyacinthoides hispanica: Wikimedia Commons

NOTE: There is another early-spring plant called bluebells, Hyacinthoides hispanica, also known as wood hyacinths or Spanish bluebells, of the family Asparagaceae. Grown from bulbs, these plants produce clumps of strappy leaves and very pretty blue bell-shaped flowers along tall, sturdy stems. These perennials are not native, and multiply rapidly, sometimes into unplanned or undesired places. The plant has been categorized as an invasive by the Exotic Management Team of the National Park Service.

DWARF CRESTED IRIS

Iris Cristata; Kid Cowboy, Wikimedia Commons

Now we’ll leave the Boradacineae family and consider Iris Cristaa, commonly called Dwarf Crested Iris, of the family Iridiceae. This low-growing, rapidly spreading plant is native to North America. It typically grows to 3-6” tall and features pale blue, lilac, or lavender iris flowers with gold crests on the falls. Flowers are borne on very short stems, often appearing nearly stemless. Narrow, sword-shaped, yellowish-green to medium green leaves about 6” long provide an attractive ground cover. The plant spreads quickly through a network of branching rhizomes and forms dense colonies in optimum growing conditions. This is an excellent plant for early spring bloom in a shaded area of the rock garden, perennial border or woodland garden. Conditions should mimic its native setting: somewhat acidic, well-drained, humusy, most soil in shade to partial shade. Although it can also tolerate some sun, more moisture is required in that setting. Soil that is too rich will promote excessive vegetative growth. When in flower, a well-developed bed can produce a spectacular drift of violet-blue color. It is easily grown from bulbs planted in the fall, or it can be divided in the fall once the foliage turns yellow. As with other bulb plants, dividing the rhizomes every few years will reduce overcrowding and help to invigorate the plants. The plant is a good nectar source for bees and hummingbirds. It is deer resistant, but monitor for damage from slugs and snails.

SUMMARY

The  Boraginaceae family offers several blue-flowered, spring-blooming perennials that thrive in shade and are deer and rabbit resistant (with the exception of Virginia bluebells). Some also offer interesting foliage after the flowers fade. Iris cristata of the Iridiceae family offers a striking blue flower, deer resistance, and shade tolerance. With such desirable characteristics, any or all of these specimens could be excellent additions to brighten the spring shade garden!

SOURCES

www.plantdelights.com/collections/blue-flowers

“Brunnera microphylla,” www.missouribotanicalgarden.org/PlantFinder/

“Why Blue Is the World’s Favorite Color,” www.artsy.net/editorial

“Plant Evaluation Notes: An Appraisal of Pulmonaria for the Garden,” www.chicagobotanic.org

“Shade Gardening with Colorful Foliage,” www.chicagobotanic.org/colorful_foliage

“Pulmonaria officinalis,” www.missouribotanicalgarden.org/PlantFinder

“Plant Sport Mutations – What Does It Mean When A Plant “Throws A Sport,” www.gardeningknowhow.com/plant-sport-mutations

“Mertensia virginica, “www.missouribotanicalgarden.org/PlantFinder

http://www.lewisginter.org/virginia-bluebells/

http://vnps.org/wildflowers-of-the-year/1989-virginia-bluebells/

http://www.illinoiswildflowers.info/woodland/plants/bluebells.htm

“Iris cristata,” www.missouribotanicalgarden.org/PlantFinder/iris cristata

“Iris Cristata,” Lady Bird Johnson Wildflower Center, wildflower.org/ iris cristata

“Iris cristata, dwarf crested iris,” Northern Virginia Master Gardeners, mgnv.org/plants/ground-cover/iris-cristata