Helleborus at OpdeHaar gardens
On this page on helleborus there is information on:
- Helleborus niger and Helleborus orientalis
- Hellebore Virus necrosis virus ( HeNNV)
- Photos of hellebores at OpdeHaar
Gardeners have access to a variety of different species of hellebore but the following notes are restricted to H.niger, H.orientalis and their hybrids. In short, the colourful plants which together with snowdrops, herald a new gardening year and are particularly useful as woodland plants. Graham Rice has written an excellent reference for anybody interested in all aspects of hellebores. I actually agree with Mr Rice, “Buy the book”. The Christmas Rose, H.niger, is found naturally in Alpine woodlands and it’s white flowers are frequently shown poking through a layer of snow although this is invariably sometime after Christmas in real-life gardens! The flowers of the natural species do rather “hang their heads” and point towards the ground but various selections and hybrids are increasingly available where flowers are more visible and outward facing – fully upward-facing flowers can be damaged by snow and rain.
Something of what is going on to expand the range of Hellebore hybrids available is revealed by Thompson & Morgan and both Internet and literature such as the earlier reference to Graham Rice, reveal a wealth of additional information. Some plants available in garden centres are stunning in the numbers of flowers, buds and leaves and have captivated several visiting friends who have presented them to us as presents over recent years. Many such plants have been forced and brought to undoubted visual perfection in a greenhouse but can be unbelievably pot-bound. I’ve had and seen spectacular plants which, on being slipped out of their pot, reveal just a solid, impenetrable mass of roots with no visible compost at all. Successfully planting these out into the garden is all but impossible so be warned and check any plants before you are tempted into a purchase.
The key to successfully cultivating Hellebores (and any plant) is to be cognisant of their natural growing conditions. H.niger from Alpine woodlands appreciates some lime in a well-drained, humus-rich soil with light shade. They hate wet conditions. H.orientalis and hybrids are a bit more tolerant and do acceptably well even in lightly acidic soils and can take more sun. For owners of country woodland gardens, these hellebores are also rabbit and deer-proof! Here in our gardens, conditions can be very acidic and we have calcifuge shrubs such as rhododendrons and camellia which aren’t regular companion plants for hellebore hybrids. While I do occasionally spot-treat the hellebores with lime, my usual trick is to put bits of cement amongst their roots (+ mycorrhizal booster) when I plant them. Bearing in mind that plants are forming buds and getting into growth in the winter months, a top dressing and some general fertiliser in Autumn is also beneficial. Carefully cutting away old leaves prior to flowering lets one appreciate the flowers better.
Hellebores are generally fairly problem-free but one does need to keep a careful watch out for “Black Death” … Hellebore Virus necrosis virus (HeNNV) or “Hellebore black death” is something which, once seen, is readily recognisable and the RHS have a succinct review on this incurable and invariably fatal affliction. It is a virus disease spread by aphids and the symptoms are not always immediately apparent such that somebody like a specialist nurseryman or collection holder can be faced with destroying his stock plants. The one saving grace is that the disease does not transmit via seeds. It is important to realise that sharply defined, circular black spots on leaves are symptoms of another type of fungal infection which is treatable (burn the leaves and spray with fungicide). If this disease becomes a severe problem or there are reports in one’s neighbourhood, one should consider the quarantining of newly purchased plants for a season and treating hellebores to keep them free of aphids.