Kent Alpine Gardener's Diary
This entry: 20 March 2017 by Tim Ingram
Hellebores - Part 1
Hellebores - Part 1
The March 1967 Bulletin of the Alpine Garden Society (Vol. 35) begins with a detailed article by Brian Mathew entitled 'A Gardener's Guide to Hellebores'. Twenty-two years later this was expanded in his fine monograph 'Hellebores' (1989), published by the Alpine Garden Society, in which fifteen species are described. In the garden its hard to imagine hellebores growing without snowdrops, and comparing their natural distributions shows the former with a 'centre of gravity' in southern-central and eastern Europe, but with Helleborus orientalis further east, following the southern coast of the Black Sea across into the Caucasus (where so many species of snowdrops are also found).
(This picture doesn't show the numbering clearly, but for those with good eyesight here is the legend. For those who haven't, please buy a copy of Brian Mathew's book 🙂).
More recently in the excellent 'Hellebores. A Comprehensive Guide', by C. Colston Burrell & Judith Knott Tyler (published by Timber Press, and valuable both for the perspective of cultivating hellebores in N. America, and for the many references to the people who have been instrumental in popularizing the genus), between 17 and 20 species are recognised. The genus has enduring appeal and interest for the gardener.
In the February talk to our local Group of the AGS (East Kent - meeting just south of Canterbury), Don Palmer gave us an enjoyable overview of the genus with plant material from various members' gardens as examples.
This winter and spring has been exceptionally good for hellebores in the garden - they have rarely flowered as well, perhaps as a consequence of the long hot and dry summer we had in the south-east in 2016, closer to the more continental climate that many experience in the wild. We grow a good number of true species, as well as many hybrids from different sources, and they also make strong connections to admired plants-people such as Jim Archibald and Elizabeth Strangman. So in this and the next entry (Part 2) I will describe our experiences with the genus and a desire to grow more of these again as nursery plants, as well as to increase the diversity of the true species that we grow in the garden.
The interest in hellebores is strong in Europe, N. America, and Japan as well, and breeding has taken the genus far from the wild species in both colour and form, with some extraordinary hybrids (a number of which begin to lose the charm and poise of the natural species, as so often happens in horticulture). It can be good to look back to the earlier days of breeding when plants were generally crossed within the garden and selected more for their garden worth than dramatic appearance. From a nursery perspective lack of demand can limit the commercial value of the species and more traditional hybrids, but as part of the garden scene these are often the most in harmony with other woodland perennnials.
A nice place to start is this small piece of woodland, low lying in a valley not far from Faversham, which a friend let us know is a superb site for the native Helleborus occidentalis (viridis subsp. occidentalis).
Here there are literally thousands of plants flowering before any other understorey plants have emerged in quite damp alkaline soil. The fresh green flowers of this species are delightful caught by the late-afternoon light, and though the flowers are small they are full of charm in the English countryside in mid-February.
We aim to return and collect seed from this location later it the year and establish the native H. occidentalis in the garden.
Helleborus viridis itself, from western and southern Europe, has larger flowers of rather beautiful apple-green that can glow caught by the low winter sun, and has made a fine specimen in the garden (one of several true species kindly given to us by David Stephens). These two very similar species are discussed in detail by Will McLewin and Brian Mathew in The Plantsman (New Series), Vol. 1 (2002), who conclude that the differences between them are sufficiently significant to regard them as distinct.
Most of the true species of hellebores have flowers varying from green to greenish-yellow or yellowish-green. Colour is not important for their pollination, but generally is for the eyes of the gardener. So they can be less and less likely to be grown in gardens. But another strong feature of hellebores is their foliage, which in many species has impact year-round. Several, notably H. multifidus and the recently described H. abruzzicus (see The Plantsman (New Series) Vol.5, 2006), can have exquisite finely dissected leaves, even if to the gardener's eyes subdued in flower. Here we are we crossing within and between plants to obtain true-breeding seed of H. multifidus subsp. hercogovinus, which has the most divided foliage of any hellebore.
This species is very variable like most plants, and has been subdivided into a number of subspecies. Another that we grow, but so far haven't managed to collect seed from, is H. multifidus subsp. istriacus, again showing the characteristic highly divided leaves.
These plants are much less available from nurseries, and generally less easy to grow in the garden, but of considerable interest to the plantsman. For us H. multifidus subsp. hercogovinus has grown well in open sunny spots, along with bulbs and Mediterranean-climate plants, and this spring has flowered especially well. But the flowers can be vulnerable to mice, as the young developing flowers of many hellebores often are, and we are lucky that in this year (so far anyway) this has not been a problem. Helleborus multifidus is fully deciduous, unlike most hellebores, but the foliage that develops after flowering is really striking. A hybrid that captures some of this form, that has arisen next to our original plant, shows that breeding with this species could have horticultural potential - resulting in hybrid vigour. There are forms of H. multifidus (or natural hybrids ?) subtly shaded purple (pictured in the most recent book on the genus published by Timber Press) and these heighten that draw that species hellebores have for the gardener of botanical bent.
(This hybrid plant flowered in early January in 2016 and considerably later this year, but as with all hellebores the flowers continue looking good for many months. The earlier flowering in an especially mild winter probably led to more damage generally from rodents last year).
Apart from the second British native, and well known garden plant, H. foetidus (which is short-lived but always self-seeds freely, and of which there is interesting variation - especially in the red-flushed 'Wester Flisk'), the only other 'green' hellebores we grow are H. dumetorum and H. odorus. The first is one of the least known and most distinct species for its very small cupped soft-green flowers, and is comprehensively described by Will McLewin and Brian Mathew (The New Plantsman, Vol. 3, 1996). It really is a charming plant which because of its small flowers and rarity has not been used in breeding, but as with H. multifidus could have interesting potential. Just as it is though it makes a delightful addition to the garden and is easy and tolerant under varied conditions. These two pictures show it in 2015 and in this winter 2017.
We grow two forms of H. odorus, one with decidedly warm yellow-green flowers from Blackthorn Nursery, and a second, more typically apple-green, from David Stephens. Both have made strong and vigorous plants, the former crossing with neighbouring H. x hybridus to produce a range of intermediate seedlings (in the first picture). This highlights the difficulty of keeping true species and collecting seed of these in the garden. We would like to raise more authentic plants from the various species we have, and from wild collected seed.
In his monograph Brian Mathew says that 'H. purpurascens, in its best forms, is one of the most charming of all Hellebores... The most attractive and typical variants are those with saucer-shaped flowers of dull purplish-violet overlaid with greyish 'bloom'...' This is certainly true of the only plant of this species we grow and gives a special incentive to propagate it and establish more plants. The colour is subtle and rather beautiful, likened by E.B. Anderson to that of a dove or pigeon.
The final two species we grow, other than H. orientalis (which I will introduce along with the H. x hybridus forms in Part 2), are H. atrorubens and H. torquatus. Helleborus atrorubens is small flowered and often richly coloured, a good potential parent for smaller flowered hybrids which would be distinct from many of the present H. x hybridus plants, and perhaps appeal to gardeners in different ways. Again as a plant in itself it is very appealing.
And finally comes H. torquatus, which horticulturally is a small plant with the most retiring of flowers of any hellebore, often in shades of purple to black, but sometimes most beautifully coloured internally blue-green with purple veining. For the plantsman it is an especially exciting species, but for the gardener more of value for the dark colours it has introduced into hybrids with H. orientalis and other species. We also grow a double form (Tinkerbell Group) raised by Robin White at Blackthorn Nursery, which like many snowdrops only shows its true fascination when observed closely. And H. torquatus is particularly famous for the two double-flowered plants that Elizabeth Strangman found and introduced from Montenegro, 'Dido' and 'Aeneas', which led on to the breeding of many smaller double-flowered hellebores. On the whole these are less robust than H. x hybridus types but can grow well, and are horticulturally popular.
As with snowdrops, but in a rather different way, the species hellebores have become eclipsed by the horticultural hybrids - but in the latter case by deliberate breeding, which only more recently has become a feature of the horticultural development of snowdrops. Snowdrops you might say have proliferated to a definite excess, but because they tend to be viewed in an intensely personal way, and have developed a 'value' because of when they flower - and for the nurseryman when there are fewer other plants that attract customers in the quiet winter months. My earlier entry tries to place some perspective on this - and snowdrops definitely act to 'prime' the spring garden, which gives them a different type of value for the gardener as well. Hellebores make stronger connections to many significant nursery and plants-people who have made important contributions to the specialist realms of horticulture for the range of plants they grow, and have grown and introduced to gardeners, in addition to this genus itself. These are some of the people and plants I would like to introduce in Part 2, along with the use of hellebores in the garden and how they associate with other plants.