Perennial geraniums (Geranium sp.) are flowering plants that act as groundcovers by using their sprawling habit to fill in bare spots or meander among other plants in a landscape. These geraniums are herbaceous plants, which die to the ground as winter season arrives, and come back in spring, though in milder climates, some species, or their related hybrids, can remain evergreen.
Gardeners identify the hardy perennial geranium through their heavily dissected palm-like leaves and the many simple five or seven-petal flowers that bloom along their stems. The perennial geranium is also called a hardy geranium, distinguished from the annual geranium, marked with big full blossoms.
The foliage gives off a lacy undergrowth. Up close, the leaves can be large and deeply lobed or smaller and finely toothed depending on the species or hybrid varieties. Beyond the low spreading characteristic associated with perennial geraniums, some geraniums form an upright busy habit or a clumping form.
Cranesbills Named for the Geranium’s Seedpods
The genus of Geranium has a little more than 400 species in its group. The most widely-known among gardeners are the perennial geraniums that English gardeners dubbed cranesbill for the seedpod that develops at the center of each spent flower.
Some observers feel that the long center in the middle of the fruit capsule, which disperses seed by flinging it far afield, emulates the appearance of a bird’s beak such as the crane’s bill.
Geranium flowers primarily bloom in hues of cool colors, white or in a mix. You will not find a pure red flower even among the deepest rose or cayenne colors, although there are species that excel with their foliage tinged in reddish hues in autumn. Individual species may be more cold tolerant, but they all like warmer zones up to 8 or 9.
Geranium ‘Rozanne’ has become one of the more popular cultivars in the 21st century. This cranesbill has a mounding habit and spans the entire summer season with bluish flowers. The Geranium x cantabrigiense ‘Biokovo’ flowers in light pink; like Rozanne before it, the Perennial Plant Association named the Biokovo Perennial Plant of the Year.
Popular Geranium Cranesbills for Groundcovers
Each of the popular species has their more famous cranesbills and geranium cultivars that gardeners have relied on more than others over the years.
Geranium sanguineum is specifically called a bloody cranesbill and, once the plant is thoroughly rooted in, it tolerates dry soil. The species plant produces a pink-white-magenta flower and the plant is tough enough for hardiness zones 3-8.
Within Geranium sanguineum you will find:
- G. sanguineum ‘Elsbeth’ with darker green leaves that still develops its red fall color, though it has a more upright habit and blooms longer than the species plant.
- G. sanguineum ‘Bloger’ – Alan Bloom – has bright pink flowers and, in particular, tolerates clay soil.
- G. sanguineum ‘Max Frei’ has a rosy flower, but the plant grows 6” – 9” tall.
- G. ‘John Elsley’ has blooms of a mauve pink hue highlighted with purple veins.
G. himalayense has violet to blue flowers and grows better in cool, moist-well-draining soil. G. ‘Johnson’s Blue’ is a well-known hybrid mix of G. himalayense and G. pretense and popular for its bluish color that has a pink center. The plant will grow in full sun or part shade, but the plant is less hardy the farther north you grow it beyond zone 5.
G. x oxonianum ‘Wargrave Pink’ is a hardy geranium that grows 15 – 18” tall in part shade and flowers from May through June.
Geranium cinereum is a species that grows evergreen and is specifically native to the Pyrenees Mountains; a line of mountains that is a natural border between France and Spain. G.cinereum ‘Ballerina’ produces a tiny 4 – 6” tall plant populated with grayer leaves. The bloom is a purplish pink that is deeply veined that radiates from its dark center. It is an excellent idea for a small urban garden where it can grow in a moist well-draining soil and kept out of hot afternoon sun. Another G. cinereum is ‘Lawrence Flatman’ with a pinker flower but growing on a slightly larger plant.
Perennial geraniums only need their clumps dug up and divided after many years. For instance, the hybrid Johnson’s Blue requires dividing after 4 – 5 years, but the geranium species in general, after 6 – 10 years.
Gardeners should only deadhead perennial geraniums to the base of the mound during yearly maintenance chores.
Fragrant Bigroot Geraniums
Of the perennial geraniums, large leaves and fragrant foliage in addition to roots that are thick rhizomes distinguish bigroot geraniums, making the plant excellent for erosion control.
The bigroot geranium is also referred to as a scented cranesbill. Geranium macrorrhizum withstands hardiness zones 3 – 8.
An evergreen, G. macrorrhizum is a type of bigroot geranium that produces flowers in pink-purple. The plant likes part shade location in warm climates but will grow well in full sun in colder regions. The flowers generally bloom May through June.
Geranium macrorrhizum ‘Bevan’s Variety’ opens its flowers as early as April where the weather is warm and continues blooming through the middle of summer. The deep magenta flowers have a pendulous form and sit above large dark green leaves. These leaves have five lobes that are tinged with reddish bronze in autumn.
G. platypetalum is a broad-petaled geranium. It has a blue flower with deeply veined petals during the first part of summer. The aromatic leaves grow on a plant that has a vigorous spreading and clumping form.
Hardy Geraniums in a Variety of Garden Styles and Plant Combinations
The perennial geranium (Geranium sp.) is a cold-hardy plant that gardeners should not confuse with the annual geranium (Pelargonium sp.). Although both are pretty in the garden, the Pelargonium only blooms for one season where grounds freeze in winter. Together, their names provide a lesson in the language gardeners speak.
Hardy geraniums work for a variety of gardens. Though the plants are only natives in Europe and Asia, the perennial is at home in cottage gardens everywhere.
Butterflies will find the blooms of perennial geraniums no matter where the plant grows, though this plant is not appropriate for a purely native garden in North America. Foraging deer do not appreciate the taste of perennial geraniums and, so the hardy perennial may do well in landscapes at the back of an open yard for this reason.
The hardy geranium is a valid choice that will mingle well because of its growing habit. The rock garden is a good location for this perennial as it can easily scrabble over the terrain and thrive among many low-growing shrubs and perennials that love similar climates.