Growing Guide Helleborus (Hellebore, Lenten Rose)
These aristocratic, evergreen plants bring an architectural quality to the shady garden. Most bloom in early winter in mild climates and in late winter or very early spring where the ground freezes hard. Resistant to both deer and voles, these plants are long-lived and provide exquisite blooms at a time when flowers are a scarce delight.
Light/Watering: Drought-tolerant once established, Hellebores are at their best in evenly moist soil in partial shade. Water well during extended dry periods.
Fertilizer/Soil and pH: Hellebores grow best in moist but well-drained soil enriched with copious amounts of organic matter. The hybrids known as Helleborus x hybridus (previously called Helleborus orientalis) prefer a soil pH close to neutral and even alkaline; add lime if your soil is extremely acid. The Christmas Rose (H. niger) may be slow to become established; to help it along, try a dose of magnesium in the form of Epsom salts or dolomitic limestone sprinkled around the plants. Plants will benefit from a light application of granular, balanced fertilizer in early spring.
Pests/Diseases: Watch for slug or snail damage, and control with baits or diatomaceous earth.
Companions: Hellebores are lovely with other denizens of light shade such as Ferns, Tiarella, Campanula, Alchemilla, Hosta, Phlox divaricata, and Pulmonaria, and truly enliven woodland gardens. The larger, more exuberantly colored varieties or double forms are a great addition to the shady border.
Pruning: Although evergreen, the foliage often looks tattered in early spring. Prune back dead and disfigured foliage before new growth appears. Remove old flower stems when they decline, cutting back to basal foliage, but take care not to remove the stems of Bear’s-foot Hellebore (H. foetidus), because they carry the flower buds formed in the previous growing season. If seedlings are not desired, remove old flowers before seed is set.
Dividing/Transplanting: Although plants may be slow to settle in, once they do, they rarely need division and may resent it.
End-of-Season Care: Do not prune back now; wait until early spring. Mulch with salt marsh hay if desired.
Calendar of Care -- Helleborus
Early Spring: Apply a light application of balanced or slow-release fertilizer or side-dress with compost and organic amendments when new growth appears. H. niger may benefit from a side-dressing of Epsom salts or dolomitic lime. Prune back old foliage to make room for new growth. Transplant now if desired.
Mid-Spring: Water well if it is unseasonably dry as plants prefer evenly moist soil.
Late Spring: Watch for slug or snail damage and control if necessary. Remove old flower stems as they decline, and deadhead if seedlings are not desired.
Summer: Pull out any unwanted new seedlings as hybrids may not come true from seed; move desirable species seedlings to permanent locations. Groom plants by removing yellow or dead leaves.
Fall: Add lime to acid soil for H. x hybridus if a soil test shows a pH under 7.0. Do not prune back for winter, but a light mulch of salt marsh hay may be beneficial.