Hellebore (Helleborus), the late winter charmer, is a perennial with nodding flowers. Native to Europe and Asia, the wild species are rarely found in gardens as hellebores hybridize easily, providing garden plants with superior flowering and color.
Commonly called Lenten rose, hellebores give pleasing late winter color, texture, and style to a garden in areas between deciduous shrubs and under trees or naturalized in woodland areas. They can be the stars of the late winter to spring garden as specimen plants, in masses as a foil for spring bulbs and could even be used as a ground cover. Combining Lenten rose with other spring-blooming perennials such as barrenwort (Epimedium spp.), wood anemone (Anemone nemorosa) and Hepatica makes a charming design. Later in the season, the foliage provides a nice backdrop for Hosta and other shade plants. They are excellent for planting on a hillside above a path where the downward-facing flowers give a sweet nod viewed from below.
Hellebore is hardy from a warm USDA zone 9 down to zone 5 (and colder when plants have winter protection with good snow cover). Not all plants are hardy throughout this entire range, so check that the plant you have your eye on is a suitable match for your location. While known to be somewhat drought tolerant, plants thrive best in moist, well-drained soil in sun (4 + hours) and afternoon, bright shade. (In more southern locations, they require more protective shade.) As mature plants they can form clumps that are 18” to 24” tall and 24” to 30” wide. The glossy, deep green foliage can be quite variable in color and shape, even within the same hybrid. The leaves, with an umbrella-like shape, have tough, almost woody stems with both leaves and flowers on the same stem. The toothed, leathery foliage remains attractive throughout the growing season, remaining evergreen in mild climates and even persisting under snow (but decline over the winter, often flattened on the ground).
Flower buds form during the previous summer, with the distinctive, 1 - 2” wide, long-lasting flowers blooming in early spring along with daffodils and tulips. Five petal-like sepals (a modified calyx) surround a ring of small, yellowish-green, tubular, nectaries in an open, bell shape. The nectaries are actually the petals modified to hold nectar. Inside the ring of petals there are numerous stamens and several pistils. After the flower is pollinated the petals and stamens fall off but the sepals do not drop, remaining on the plant for 1 - 2 months or more (probably contributing to seed development). Mature plants could have 50 or more flowers per plant. Blooms make good cut flowers and their seed heads add interest in dried arrangements.
Like other members of the Ranunculaceae family, hellebore has alkaloids in the leaves and seeds that can cause mild dermatitis in sensitive individuals, so wear gloves when exposure might occur. These same alkaloids make the leaves undesirable to deer and rabbits, but slugs like the flowers.
This is a low maintenance plant, relatively drought tolerant once established, but does best with consistent moisture in well-drained soil (amended with organic compost). Plant hellebore any time in the fall or early spring when soil is workable after initial soil preparation. Choose a spot in sun (4 + hours) and afternoon bright shade.
Plants are very sensitive to soggy soil and will rot if the location is too wet. Deep root systems benefit from extensive incorporation of organic compost, leaf mold or well-rotted manure when preparing the planting site. Mix some slow-release, organic fertilizer in to the planting area. Take care not to cover the crown of the plant with soil when planting. Planting too deeply reduces flower production.
Hellebore grows best in gentle rather than full shade conditions. Deeper shade is tolerated but will reduce flowering. Morning filtered sunlight and afternoon light shade is appropriate. Planting hellebore under deciduous trees offers a wintry protected area with tree foliage providing dappled light.
Water plants deeply once a week if there is no rain. You can test the top few inches of soil with your fingers to see if more water is needed. The soil should feel lightly moist, but not water-logged or soggy. If​ you deal with soggy soil in your garden, a sloped location is ideal to maintain drainage.
Highly organic soil is the best source of nutrition; organic compost amended soil provides happy growing conditions. In addition to the slow release fertilizer incorporated at the time of planting, you will need to feed your plant only once a month during the growing season with a bloom-boosting fertilizer. Mulching will help to maintain a moister soil but take care not to heap too much mulch around the plant base and stem.
Hellebores are hardy, long-lived perennials that often naturalize or spread in ideal growing conditions. For that reason, they don't typically need to be divided or want to be. (They do have a deep root system.)
None-the-less, you may want to use division as a form of propagation. Seedlings will usually not be true-to-type so division is preferred for enlarging the cover of plants with desired characteristics.
When to divide: early fall is the best time to divide hellebore. At this time, the plants have already flowered and set seeds, and are typically still healthy and hardy. Avoid the heat of mid-summer. (Plants may go somewhat dormant in the hot summer season).
How to divide and transplant: you will need gloves, shears, sharp shovel, and a bucket of water. Wear gloves when dividing hellebore because the sap can cause skin reactions in some people. Dig up the entire mature hellebore plant with a sharp shovel and lift it out of the ground. If the ground is dry, water around the plant to soften and moisten the soil. Once the crown and root system are exposed, use a clean pair of shears to divide the plant into your chosen number of sections. It's recommended to divide the plant in half or in thirds, depending on the size of the root system. Keep the roots of the divided sections moist; it's helpful to place them in a bucket of water. Transplant immediately.
Hellebore can bloom from late November through winter until spring, depending on the species or hybrid and your location. The leaves provide a carpet of foliage throughout most of the year in some areas. Come summer, many hellebores start to look peaked but will perk up and send out tender fresh foliage in September and October, once the weather cools down and ample moisture is available.
The foliage that emerges before flowers bloom (or that's left over from the last season) can look winter-tattered. Prune this old foliage off as the hellebore starts to flower. Or, prune out the older foliage after a few years when new leaves start to emerge, about two months after bloom starts. It all comes to personal preference and your aesthetic. The leaves are not great additions for your compost pile; the leathery texture make decomposition a slow process.
Plants appreciate an annual addition of fresh organic compost to the growing area to refresh soil texture and nutrients.
While hellebores are relatively trouble-free, there is an emerging threat from a viral disease that is known as Hellebore black death in Europe where it is more common. Helleborus net necrosis virus (HeNNV ) is not widely known or observed in the US, but it is present in multiple states. It is believed to be carried on the feeding parts (stylets) of aphids. The latency period, from when the virus is transferred to when it expresses itself, can be as long as 18 months. It is not currently believed to be transmissible to other plant varieties.
The delayed expression of the virus means that symptoms are often noticed on older, well-established plants. Typical symptoms include:
There are some more common, less problematic, hellebore diseases that have similar symptoms including the much more common fungal leafspot caused by Microsphaeropsis hellebori (syn. Coniothyrium hellebori blackspot), and Botrytis cinerea. Hellebore leaves are also commonly "burned" by the cold winds of early spring. Fungal leafspot most typically causes concentric ring lesions on leaves and Botrytis cineraria the blighting of leaf and flower, but the symptoms are not always clearly differentiable from hellebore net necrosis virus which can produce similar symptoms. These fungal conditions are less serious and can be treated by removing and destroying the impacted plant tissue. Helleborus net necrosis virus cannot be cured and requires removal and destruction of plants.
The black death virus has been observed in Europe since the early 1990’s. Studies of the disease by Washington State University, examining strains found in the United States, determined that this disease is a Carlavirus, a group of viruses transmitted by insects for which plants serve as hosts and distinct from any previously encountered viruses. The insect vector for this disease has been assessed to be the hellebore aphid, which proliferates on hellebores. Not all aphid species are able to transmit all viruses and other aphid species have not yet been demonstrated to transmit this disease. It is believed to be carried on the feeding parts (stylets) of aphids but is not internalized (non-persistent transmission), thus the disease is carried for a period no longer than a few minutes.
Because the virus is transmitted on the feeding parts of aphids, preventing feeding is the most promising management technique in nursery greenhouse settings. There are systemic insecticides that are licensed for these settings in some states. Use of insecticides on home gardens to deter aphids, however, would not be effective or practical as a very short-interval repeat of application in an open environment would be needed.
We are not able to confirm a diagnosis from your photos as the symptoms vary and mimic other diseases. If you notice symptoms on your hellebores, you can contact your county's cooperative extension office as a first step to arrange to have the plant material tested by their labs.
The Gardeners' Guide to Growing Hellebores by 
Hellebores by 