Herbaceous Ornamental of the Month: Helleborus niger, Christmas Rose
Posted: February 16, 2012
Helleborus niger is hardy in zones 3 to 8 and typically grows 12 to 18 inches tall. Hellebores are divided into two groups, those with stemless foliage that arises from the rootstalk of the plant, and those that produce an above ground stalk from which leaves develop. The Christmas rose falls into the stemless category which is referred to as acaulescent. The leathery, evergreen foliage is palmately divided, usually with serrations on the leaf margins.
Because the species is widely distributed there is much variation in the size, color and bloom time among plants. Unlike most hellebores which have nodding blooms, the snowy white flowers of the Christmas rose face outward. Hellebores lack showy flower petals. Instead, the two inch blooms are composed of five sepals that hide the numerous inconspicuous petals. The sepals surround a large cluster of yellow stamens. The flowers can persist for two months or longer depending on temperature. As the sepals mature they take on rosy pink or green hues.
Seed pods form soon after pollination. By the time the seed matures the sepals have faded to green and the seed pods are swollen. It is recommended that the seed pods be removed to encourage robust plants; however, if allowed to persist, numerous seedlings will develop around the base of the plants.
Plants thrive in partial shade and soil that is rich in organic matter. They are perfectly suited to a woodland garden. Unlike the Lenten rose, set the crown of plant just below the surface of the soil when planting. Helleborus niger typically grows in a limestone soil so amending the area with an alkaline organic material such as mushroom manure is beneficial. Plants will also benefit from an annual sprinkling of ground limestone. Plants are slow to mature but will form large showy clumps that will remain vigorous for years. Hellebores can be divided in the spring, but Helleborus niger often suffers a setback after division and may not bloom for several years afterward. It is preferable to propagate the plant by transplanting the seedlings that develop around the base of the plants.
The Christmas rose is relatively insect and disease free although it may be plagued by fungal leaf spots that cause brown, desiccated areas on the leaves. Prevention is important; clean up old stems, leaves and debris that may harbor disease and overwintering insects. Copper-based fungicides are helpful in preventing leaf spot if the problem is treated early. Plants are also subject to winter injury from cold, winter winds that may cause desiccation of the foliage. Generally, hellebores are not browsed by deer.