Carefree Cranesbills
by Ricbard Hawke

With their long blooming season and easy culture, hardy geraniums are tough to beat.

An explosion of new cranesbill varieties has hit the market over the past 10 years. This isn’t surprising, given the attributes these stalwart perennials display, including a lengthy blooming period, attractive foliage, and a robust and adaptable nature, not to mention their propensity to hybridize in cultivation. And today’s selections defy the Victorian complaint that cranesbills were too wild or coarse for the garden; many new varieties boast improved growth habits, an even more floriferous nature, and a tantalizing array of flower and foliage colors.

Cranesbills or hardy geraniums, the common names that refer to approximately 300 species of the genus Geranium, are widely distributed in temperate regions of the world. Although they share familial similarities, cranesbills are varied enough in their ornamental traits and cultural needs that even a small garden can feature several different selections without appearing to lack diversity.

Since 1997, I have grown and evaluated almost 150 different cranesbills at the Chicago Botanic Garden (USDA Hardiness Zone 5b, AHS Heat Zone 5). We have identified the best for northern gardens based on their superior ornamental qualities, cultural adaptability, pest-free nature, and winter hardiness. Many of these varieties thrive in other regions as well.

Getting to Know Cranesbills

Cranesbills flaunt their flowers in shades of blue, purple, magenta, pink, and white; darker or contrasting veins commonly streak the petals, an adaptation that helps attract pollinating insects. Acting as a landing strip of sorts, the lines guide insects to the nectaries located at the base of each petal. Each saucer-shaped blossom has five petals, often notched at the tip, and some sport a white or dark eye. Flowers range from one-half to two inches wide, and, depending on the selection, bloom over a period of about four weeks to five months, from late spring into autumn. Those with especially long bloom periods include some of the newest selections such as ‘Jolly Bee’, ‘Nimbus’, ‘Orion’, Rozanne, and ‘Tiny Monster’.

Both the botanical and common names arise from the resemblance of the fruit to the beak or bill of a crane; Geranium derives from geranos - “crane” in Greek. The distinctive fruits burst open upon ripening, dispersing seeds up to several feet away. For some species, including G. 5oxonianum and G. pratense, this may result in an abundance of seedlings and a tendency to be weedy. Cranesbills are notoriously promiscuous and will hybridize with other cranesbills nearby in the garden.

Cranesbill leaves are palmately lobed and often deeply dissected. Shades of green to gray-green predominate but plum-purple and golden green selections exist; other selections are variegated, blotched, or banded with cream or purple. In autumn, the foliage of many cranesbills turns purple, red, orange, or yellow. Some species have aromatic foliage, but depending on your sense of smell, the fragrance may be described as minty, medicinal, or malodorous.

Cranesbills offer a diversity of habits too - from mounding to trailing, clump-forming to spreading, from a few inches to several feet tall. Because they blend and weave comfortably with other plants, cranesbills make good garden companions. The following selections are a sampling of the many cranesbills we found to be exceptional in our trials.

Sunny Selections

A new generation of blue-flowered cranesbills is taking the gardening world by storm, with award-winning Rozanne (‘Gerwat’, Zones 5–8, 12–2) and lookalike ‘Jolly Bee’ (Zones 4–8, 8–1) among the best. Most blue-flowered cranesbills contain a hint of pink, but these selections come pretty close to true blue. In side-by-side trials their differences are negligible; both feature large two-inch blue flowers with white centers and purple veins, from early June to frost. Their vigorous sprawling habits, 18 inches tall and 48 inches wide, are similar too.

For many years, ‘Johnson’s Blue’ (Zones 4–8, 8–1) was the most popular blue-flowered cranesbill. Unfortunately, it has the bad habit of toppling over during flowering, which diminishes the floral display. ‘Johnson’s Blue’ has been superseded by ‘Brookside’ (Zones 5–8, 8–1), a vigorous selection that grows 24 inches tall with a 36-inch spread. It grows more upright in full sun, producing deep blue flowers, each with a small white eye and reddish veins, from late May into mid-August in northern Illinois.

Blue Sunrise (‘Blogold’, Zones 5–8, 8–5) is a colorful selection that features dissected golden chartreuse leaves in spring. This color fades to yellow-green just as the lavender-blue flowers open in late June and continue to late July. The combination of yellow and blue is especially brilliant in a sunny site, but Blue Sunrise grows admirably in part shade. This well-mannered cranesbill reaches 24 inches tall and 36 inches wide.

Long-blooming ‘Orion’ (Zones 5–8, 8–5) displays copious deep purple-blue blossoms from late spring into late summer. ‘Orion’ has a robust, spreading habit, 24 inches tall and 30 inches wide at peak bloom in mid-June, sprawling to twice that width before the last flowers fade. Although ‘Orion’ is a seedling of ‘Brookside’, it has more in common with ‘Nimbus’ (Zones 5–8, 8–5), another notably floriferous cranesbill. ‘Nimbus’ is also long-blooming and, like ‘Orion’, its purple-blue flowers become paler in hot sunny gardens. ‘Nimbus’ is a vigorous plant, reaching 24 inches tall and 36 inches wide in sun and a bit taller in part shade.

When asked to recommend perennials for a garden, my first response is almost always bigroot cranesbill (Geranium macrorrhizum, Zones 4–8, 8–1). It is a reliable, versatile plant for shade or sun, with handsome green leaves and a refined habit, up to 18 inches tall and wide-spreading. Abundant magenta-pink to white flowers with colorful inflated calyces appear in May and June. Its aromatic leaves take on red, orange, and burgundy tones in fall and may be semi-evergreen in mild winters. Bigroot cranesbill is drought-tolerant and, unlike many cranesbills, remains tidy and healthy without deadheading or shearing. ‘Czakor’ has flowers of the deepest magenta on stems to 12 inches tall. ‘Ingwersen’s Variety’ is slightly larger with light pink flowers, while ‘Variegatum’ features rose-pink flowers and variegated leaves of cream, gray, and green on 18-inch stems. Ground-hugging ‘Lohfelden’ has very pale pink flowers and a shorter habit reminiscent of G. 5cantabrigiense.…

My introduction to hardy geraniums was bloody cranesbill, Geranium sanguineum var. striatum (Zones 3–8, 8–1), a sturdy species indigenous to Europe, the Caucasus, and northern Turkey. Flowers are predominately red-purple to magenta with shades of pink and white possible, blooming from May into July with sporadic rebloom until frost. Bloody cranesbill varies in habit and size, from six to 24 inches tall and three feet wide, making it a good choice for a groundcover or the front of the border. The deeply lobed green leaves may take on red and purple tones in fall. I’m impressed by ‘Rod Leeds’, a particularly robust plant that grows to 24 inches tall and five feet wide with one- and-one-half-inch-wide magenta flowers and extra large, dark green leaves—about twice the size of typical leaves. Other top-notch cultivars include ‘Canon Miles’, a perfect 12-inch-tall mound with purple-pink flowers; light pink-flowered ‘Connie Hansen’, which grows 20 inches tall and wide; and ‘Kristin Jakob’, with bright purple-magenta flowers on stems to 14 inches tall and 36 inches wide.

Shade Lovers

Flowering plants that excel in shade are like gold to gardeners. Spotted cranesbill, Geranium maculatum (Zones 4–8, 8–1), is one of those plants. The rosy-pink to white flowers of this eastern United States native are at their peak in May. ‘Elizabeth Ann’ and ‘Espresso’ are similar plants with coffee-colored foliage and bountiful lavender-pink flowers. ‘Espresso’ has darker chocolate-burgundy leaves that fade to dark bronze after flowering, while ‘Elizabeth Ann’ fades to olive drab. ‘Elizabeth Ann’ has slightly larger flowers that are significantly darker in color than ‘Espresso’. Both cultivars are 18 inches tall and upright in habit.…

Photo credits: ‘Canon Miles’ and ‘Blue Sunrise’ by Richard Hawke; ‘Rozanne’ by Jerry Pavia
 

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