Planted at Riverbanks Botanical Garden, ‘Molly’s White’ (Helleborus x iburgensis ‘Molly’s White’ PP#25,685) from the Frostkiss® series has white flowers and marbled blue-green foliage. It is a hybrid between acaulescent and caulescent species.
Ginger E. Long, © 2024 HGIC, Clemson University
Hellebores (Helleborus species) are perennials in the buttercup family, Ranunculaceae, along with clematis (Clematis spp.), columbine (Aquilegia spp.), and anemone (Anemone spp.). There are 20 species of Helleborus native to Europe and Asia. Most hellebores have evergreen foliage and bloom in winter and early spring.
There are two main types of hellebores: acaulescent and caulescent. The acaulescent species do not have stems. These include the Lenten rose (Helleborus x. hybridus) and the Christmas rose (Helleborus niger). Hellebores with stems are caulescent, such as the stinking hellebore (Helleborus foetidus). The acaulescent types are long-lived at 20 years or more. The caulescent types are short-lived, only for a few years, but they reseed freely.
Culture
Most hellebores grow in similar light and soil conditions, growing best when planted under deciduous trees, where they receive sunlight in winter and shade in summer. Morning sun or dappled sun in the summer is ideal. A few species are tolerant of more sun than others.
Hellebores prefer soil enriched with organic matter and can grow in clayey, loamy, or sandy soils. They will not tolerate wet soils. Most are native to soils that are slightly alkaline to neutral. Hellebores, such as Lenten roses, can grow in slightly acidic soil. Hellebores seldom need fertilizer. If desired, an organic fertilizer or compost can be applied. Hellebores are drought tolerant once established but will require water during long dry periods. Spread a two-inch layer of mulch around the plants.
Removing old leaves from plants is recommended to reduce the development of fungus or mildew. For most hellebores, the foliage should be removed as the new leaves and flowers emerge. The exceptions are stinking hellebore (Helleborus foetidus) and Corsican hellebore (Helleborus argutifolius). The older foliage of these species should be removed after flowering.
HGC® Ice N’ Roses® Rose (Helleborus x glandorfensis ‘COSEH 4200’ US PP #28,297) blooms from early winter to spring alongside crocus, early daffodils, and grape hyacinth.
Photo courtesy of ©Heuger (all rights reserved)
Landscape Use
Selecting hellebores with early, mid, and late bloom times can extend the flowering season from December to April.
Pair hellebores with bulbs and plants that bloom in late winter to early spring, such as crocus, Iris reticulata, early daffodils, and muscari. The flowering period of perennials like bishop’s hat (Epimedium spp.) and lungwort (Pulmonaria spp.) coincides with the hellebore bloom time. After flowering, the evergreen foliage provides a backdrop for perennials such as ferns, hostas, astilbes, anemones, and more. The evergreen foliage also provides interest when all other perennials are dormant in late fall and early winter.
Hellebores can be grown in containers for winter interest. They provide a tall accent to a container planting of pansies and violas. Other plants with winter interest, such as ivy, primroses, wintergreen (Gaultheria procumbens), and early blooming bulbs, can be combined with hellebores for a winter display. After flowering, later in the spring, they should be transplanted into the garden.
Hellebores are an early pollen source for bees and other insects. Deer and rabbits rarely browse them since all parts of the plants contain toxins.
Propagation
Lenten roses (Helleborus x hybridus), Christmas roses (Helleborus niger), and stinking hellebores (Helleborus foetidus) can be grown from seed. One method of growing from seed is to let the seeds set and fall around the base of the plant in spring. The seeds will germinate the following late winter or early spring. Most seedlings take two to three years of growth before flowering.
Seeds can also be grown in containers. The seed must be fresh since germination rates decline with age. Seeds can be surface-sown in a container of potting mix. Do not cover the seeds. Leave the pots outdoors and keep the soil moist. The seeds need the cooler temperatures of fall and winter to germinate. Later, transplant the seedlings into the garden.
Some hellebore plants, such as Lenten roses, can be divided. The best time to divide plants is when they are actively growing in the late fall to early winter. Plants can be dug up and divided using a sharp knife. Do not divide the caulescent types of hellebores. They are best propagated by seed.
Problems
This Lenton Rose has downy mildew (Peronospora pulveracea).
Xiao Yang, ©2024, Plant Problem clinic, Clemson University
Hellebores have few diseases and insect pests.
Common insect pests include aphids, slugs, and snails. The whitish-green hellebore aphid may be found on new growth and flowers. Aphid populations cluster on the tops or undersides of leaves, stems, or flowers. They produce honeydew, which leads to sooty mold. If necessary, spray insecticidal soap for control. For more information on using insecticidal soaps in the garden, see HGIC 2771, Insecticidal Soaps for Garden Pest Control.
A common fungal disease of hellebores is black spot (Coniothyrium hellebore). Black spot can appear as rounded spots on leaves or any part of the plant. Remove all infected leaves, stems, or flowers to prevent the fungus from spreading.
Other fungal diseases affecting hellebores are rhizome and root rot, where the stems will fall over at the base. Check that the soil is well drained. Downy mildew (Peronospora pulveracea) can also be a problem for Lenten roses. It is a fungal disease that will cause white or gray lesions on the foliage and flowers that can lead to the death of the plant.
A deadly virus affecting hellebores is the black death (Helleborus net necrosis virus, HeNNV). It was found in the upstate of South Carolina in 2017. Symptoms included black streaks that follow leaf margins or veins and yellow mottling of the leaves. Plants can become deformed.
Species and Cultivars
Acaulescent
The Christmas rose blooms in the winter when most other plants are dormant.
Anthony Keinath, ©2022, Clemson Extension
The most widely grown hellebores are the acaulescent (without stems) types. There are over a dozen species of these. The most readily available are the Christmas rose and the Lenten rose.
The Christmas rose (Helleborus niger) is native to mountainous regions in Europe, including the Alps in Switzerland, parts of southern Germany and Austria, Croatia, and Italy. It is hardy in USDA planting zones 3 to 8, which includes most of South Carolina. These evergreen perennials grow 9 to 12 inches tall and 12 to 18 inches wide. The flowers are outward facing, white, with bright yellow stamens and pink shading on the backs of the sepals. They bloom in winter, usually beginning in December and continuing into February. The leaves are deep green. Plant them in organically rich soil that is neutral to alkaline. The soil should be well-drained, especially in winter, and part shade is preferred. Cut back the old leaves when new leaves and flowers emerge. They are slow growers.
Lenten roses (Helleborus x hybridus) planted underneath large crape myrtles at Riverbanks Botanical Garden.
Ginger E. Long, © 2024 HGIC, Clemson University
The Lenten rose (Helleborus x hybridus) is native to Europe and Asia and is hardy in USDA planting zones 4 to 9. It can be planted throughout the state, including the coastal region. These evergreen perennials grow up to 18 inches tall and wide. The nodding and bell-shaped flowers appear in winter and early spring, lasting up to three months. Flower colors range from shades of pink, purple, white, and black to yellow. They tolerate a soil pH from slightly alkaline to slightly acidic. Plant them in light shade in organically rich, well-drained soil. For more information on Lenten Roses, see fact sheet HGIC 1185, Lenten Rose.
Caulescent
There are only a few species of caulescent (with stems) types of hellebores.
The stinking hellebore (Helleborus foetidus) is native to Spain, Portugal, England, and Switzerland. It can grow throughout South Carolina and is hardy in USDA planting zones 5 to 9. Plants reach up to 36 inches tall and 18 inches wide. Sprays of small bell-shaped green flowers appear in late winter to early spring. The leaves of this hellebore are palmate and narrow. Leaves should only be cut back after flowering. It prefers part to full shade and well-drained soil. The individual stems have a short life span of two years. However, they reseed abundantly, and new plants will replace the old quickly. Despite its common name, only the leaves have an odor when crushed.
Corsican hellebore (Helleborus argutifolius) is native to Italy, Greece, Corsica, and Sardinia. Plants are hardy in USDA planting zones 6 to 10. Evergreen plants usually reach 20 inches high and wide but can sometimes grow as tall as 36 inches. In late winter, pale green flower clusters emerge. Wait until after flowering to cut back old foliage since it blooms on old stems. The leaves are three-lobed, unlike other hellebores, and are thick, spiny, and dark green. This hellebore tolerates more sun than others and thrives in morning sun and afternoon shade. Very well-drained soil is required wherever this hellebore is grown in South Carolina.
Hybrids
Since the early 2000s, new hybrids of the acaulescent and caulescent types of hellebores have been introduced. These sterile plants produce an abundance of flowers that are more upturned than nodding. Many of these are sold in trademarked series of cultivars.
The Frostkiss® series (Helleborus x iburgensis) is hardy in USDA planting zones 5 to 8. Plants grow 12 to 18 inches tall and wide. The flowers are slightly nodding and are available in white, red, light pink, dark pink, and bicolor. Depending on the cultivar, the plants can begin blooming as early as December and continue as late as April. The foliage is marbled with a bluish cast. Plants thrive in morning sun or part shade.
From the Frostkiss® series, ‘Dana’s Dulcet’ (Helleborus x hybridus ‘Dana’s Dulcet’ PP#27,970) has dark pink flowers tinged with pale green.
The marbled foliage of ‘Dana’s Dulcet’ is bluish-green.
Ginger E. Long, © 2024 HGIC, Clemson University
The Ice N’ Roses® series (Helleborus x glandorfensis) is hardy in USDA planting zones 5 to 8. Plants grow to 15 inches tall and 24 inches wide. The flowers are outward-facing, in red, pink, and white shades and bloom from late winter to spring. The foliage is a glossy dark green. Plants are robust and disease resistant. Plant in a location that receives morning sun and afternoon shade.
HGC® Ice N’ Roses® Red (Helleborus x glandorfensis ‘COSEH 4800’ US PP #31,182) has abundant deep red flowers in late winter.
Photo courtesy of ©Heuger (all rights reserved)
The outward-facing flowers of HGC® Ice N’ Roses® Dark Picotee (Helleborus x glandorfensis ‘COSEH 5100’ US PP #32,527) are white in the center with dark pink margins.
Photo courtesy of ©Heuger (all rights reserved)
The Winter Ballet series (Helleborus x lemperii) is hardy in USDA planting zones 4 to 8. Plants can reach 20 inches tall and wide. Large flowers are upright in shades of dark to light pink, white, or bicolor. Flowering begins in December. The dark green foliage is robust. Plant in part to full shade.
HGC® Winter Ballet Leona (Helleborus x lemperii ‘COSEH 7300’ US PP#33,012) begins blooming in December.
Photo courtesy of ©Heuger (all rights reserved)
