How to grow Hellebores
Most Hellebores are low growing plants reaching about .3-.5m high and are easy to grow, indicated by the green wheelbarrow. Hellebores produce a succession of flowers from December through to spring. Some of the earliest flowering are H. 'Christmas Carol' illustrated bottom right, and H. 'Verboom beauty' which start flowering in December. Hellebores self seed and multiple into clumps as in the image left. The majority of the popular varieties of Helleborus are small plants, growing up to around half a metre, and so they make good front of the border plants and ground cover. The flowers are predominately white, cream, pink, green, and dark red. Many Hellebores have attractive markings inside the flower, shown in image far right, and because the flower heads can hang down, Hellebores look attractive planted on a bank and also look good in a woodland settings. Hellebores are usually evergreen but can be semi evergreen/deciduous in cold winters.
The more unusual Hellebore is H. 'Corsican' which as the name suggests originates from Corsica, which is green with leathery leaves, evergreen and taller than the other Hellebores at around 1.2m (4ft)
Hellebore niger (Christmas Rose) and orientalis (lenten rose) are some of the most popular garden varieties. Tolerant of most conditions, these popular group of Helleborus prefer moist but well drained alkaline soil in dappled shade. Illustrated is Hellebores orientalis with double flowers; new strains of Helleborus are being bred all the time and there are some lovely varieties on sale. The H. Verboom beauty has the advantage of being suitable for indoor or outdoor cultivation. As a very early flowering variety it can be used for Christmas containers and after flowering planted outside for the following year.
Hellebores are evergreen or semi evergreen, although the foliage can look a bit battered in winter, it can be removed in late winter /early spring. Given that Hellebores flower early in the year they are a good source of nectar for any emerging solitary bees. Hellebore flowers nod downwards which can make it difficult to see the lovely delicate interior of the flower. If you can, it is a good idea to plant them on a bank or higher up, so you can look into the flowers. Hellebores are really attractive as the array of images below shows, and Hellebores flower for a long time and are one of those plants whose flowers look good as they fade. As a woodland plant Hellebores look good with spring flowering bulbs which will flower at a similar time, such as Iris reticulata, Grape Hyacinth, Winter Aconite, Snowflake, and Fritillaria good companions to spring flowering bulbs and spring flowers.
Where to Plant Hellebores
The most popular and widely grown group of Hellebores are the niger and orientalis varieties. Helleborus are tough versatile plants, whose preferred conditions are neutral to alkaline soil with dappled shade, but will tolerate a far wider range of growing conditions excluding only very wet or very dry conditions. This means Hellebores are plants you can place in most parts of the garden. Hellebores flower from December through to mid spring although the flowers may stay on the plants longer as they fade very slowly, but still look attractive. Generally Hellebores are at their best in late winter to early spring. There are some early flowering varieties which look good in December, (image bottom right H. Christmas Carol) and look good placed somewhere you can see them from indoors, or put in tubs to create a winter bedding scheme.
Hellebores are reliable to flower every year once established with little or no attention. They self seed freely, forming a new seedling near the parent plant which will flower after two or three years a process which over time creates clumps of Hellebores( image above left) which look good in a natural or woodland setting.
Hellebores will grow without any attention, although they do better if the old foliage is removed in late winter December or January. Removal of most or all of the foliage serves several purposes. Firstly, displays the flowers at their best, leaving just the new young foliage coming through. When you cut back in Dec/Jan you will need to do so carefully as at ground level the flowers are in bud forming along with new foliage. In some professional gardens such as the RHS all of the old foliage is removed to show off the flowers.
The second reason is that Hellebores are very prone to black spot and by Dec/Jan the leaves will be showing evidence of black spot to a greater and lesser degree. This year, 2017/2018 we suffered a very wet winter and I have cut all the leaves from the Hellebores to remove the black spot infestation.
Obviously the leaves are needed for photosynthesis, which is why they can be removed in the Winter during January or February, and new foliage will grow ready for the spring ready for photosynthesis. Routine removal of the leaves in Jan/Feb will show off the flowers nicely and reduce the development of any leaf spot to which Helleborus are prone. As a woodland plant an ideal mulch is leaf mould, (image below right) although any well rotted organic matter will be suitable.
Most but not all Helleborus are fully hardy and will grow reliably year after year. Some Helleborus × hybridus are borderline which means they may need winter protection especially in more exposed gardens.
Hellebores for Particular Conditions
Hellebores are widely tolerant of most conditions if you have a particular spot in mind it is worth considering the following tips.
The Hellebores lenten rose types will grow almost anywhere, they are best in damp well drained soil in dappled shade. If grown in sunnier conditions the soil needs to be more moist.
If you want to grow Hellebores in dry shade, a varieties to try is Helleborus x nigercors or H. foetidus (the stinking hellebore, possibly not so attractive)
In sun, Helleborus x sternii and Helleborus odorus, the latter is a green variety, fragrant and both are slightly tender.
How to divide Hellebores
Hellebores can be divided allowing you to create new plants for free.
Helleborus niger (Christmas rose) is best divided in the spring and Helleborus x hybrids, the lenten rose and the orientalis varieties, are best divided in the late summer or autumn. However, Hellebores are fairly tough plants and should survive being divided at all times except when the weather is bad over the winter and/or when they are in full bloom. This means most Hellebores can all be divided in mid to late spring, and if you are not sure what type of Hellebore you have, divide it after flowering later in the spring.
To divide, lift the clump retaining as much root as possible, cut into largish pieces about 15cmc each (6") and replant, watering well. After replanting Hellebores may take a little while to re establish, which can mean a lack of flowers in the following late winter/spring, but they should start to do better after that.
There are two types of Hellebore which are not suited to division. Helleborus foetidus, known as the stinking Hellebore and it is tall, up to .5m and predominantly green, and H. argutifolius, the Corsican Hellebore (top centre image) which is similar to look at, mainly green flowers and similar size but with prickly leaves. If your Hellebores are tall with green flowers it is best not to divide them.
Problems with Hellebores - Black Leaf Spot
Hellebores are more or less trouble free except they can suffer from a common fungal problem of leaf blotch which as the name suggests means the leaves get marked with grey or brown marks. The image below shows what Hellebore black spot, and the simple solution is to cut off the leaf, or as many leaves as are infected. If the infection is severe cut off all the leaves, the plant will survive. The plant does not seem to suffer from having many leaves removed and they are replaced by new ones in the spring. Always remove any leaves which are brown or black even if it means the plant is almost denuded it will survive and as always with infected leaves, do not compost. Cut carefully as by late December/early January the new buds will be coming through, center image, and it is important not to damage these. In the third image below all the leaves have been removed in Dec/Jan and a layer of leaf mulch has been added. As such you do not prune Hellebores, they will grow to a modest size and are not over vigorous.
Hellebores can also get Black death which causes black streaking on the stems, leaves and even flowers and looks different to Leaf Spot as is distinct streaking often along the veins. Eventually if left unchecked it will kill the plant. The solution is to remove the leaves at the first sight of it, the same as with Leaf Spot. In common with many plants Hellebores can get Downy mildew, a fungus, covering the leaves with yellow spots and off white mould. Remove and bin affected leaves.
Bear in mind also that Hellebores are a poisonous plant, (humans and pets) and ingestation of root or leaves can cause stomach upsets and for some people it is also a skin irritant.