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The Genus Helleborus By Howard Drury

The Genus Helleborus By Howard Drury

 

Introduction

 

A member of Ranunculaceae, Hellebores are related to Aconitum, Trollius, Actaea, Nigella, Aquilegia and of course the common buttercups and marsh marigolds. This is a highly poisonous genera, with a long history of medical interest dating back in Greek and Roman history for over 2,000 years.  The active ingredients are reputedly found mainly in the roots, the severe irritation encountered when working with the plants, especially when seed collecting, indicates that poisons are present in all parts. It would be inadvisable to eat meals, smoke etc. without first washing hands after handling these plants. The general distribution of the genera is throughout Central and Eastern Europe, from the Alps to the Balkans. The classification and naming of these plants is complex and difficult. However the commonly grown species and cultivars should not present too many difficulties when attempting to purchase new specimens.

There would appear to be 16 distinct species of Helleborus, with many cultivars, varieties, forms or strains of the more popular species.  Difficulties arise in that there are several interspecific hybrids, with selected forms of these hybrids.

HELLEBORUS SPECIES

H. vesicarius                                          H. foetidus                               H. argutifolius

H. lividus                                                H. niger                                    H. orientalis

H. cyclophyllus                                      H. purpurascens                      H. torquatus

H. atrorubens                                        H. dumetorum                          H. viridis

H. odorus                                               H. multifidus                              H. thibetanus (Chinese sp.)

Helleborus vesicarius.

Of these 15 species, some are not particularly ornamental, and others because of their S. European and E. Mediterranean origins, are not particularly hardy unless site and soil are given careful consideration.

The species most likely to be obtainable in British Isles are:-

H. lividus                                               H. atrorubens                            H. foetidus

H. niger                                                 H. purpurascens                       H. argutifolius

H. orientalis                                         H. viridis

Helleborus foetidus - commonly referred to as Stinking Hellebore, the plant is not as objectionable as the name infers.  The unpleasant smell tends only to be released when the plants are handled, in many cases the flowers being quite sweetly scented.  A striking garden plant, it has large deeply divided evergreen foliage giving a very impressive appearance through the winter months.  Starting in early December the pale-lime green bracts of the flower heads develop on top of the overwintering mound of leaves, becoming more impressive as the flowers open through February and into March.

Similar to H. argutifolius and H. lividus, it has annual tough woody stems, carrying the impressive overwintering foliage and the equally impressive terminal inflorescence.  After flowering and developing the prominent pale green seed heads, the stems up to 80cm high die back to be replaced by up to six replacements.  The vigorous plants will once again be an impressive mound, up to a metre across by end of the growing season.  Easy to recognise, stemmed habit with divided leaves of many narrow leaflets. Some garden variants of this widespread species are available, selected forms with fragrant flowers, or all green flowers instead of being tipped maroon/brown as in the native populations.  One interesting type has rhubarb red staining of the stems, petioles and flower stalks but retaining the contrasting pale green in the flowers. A plant of open woodland over chalk or limestone, they appreciate well drained soils giving a deep rootrun with the moisture retentive surface leaf litter. Although a widespread species, often found growing in the vicinity of the above mentioned similar members of the genus, it rarely interbreeds with other Hellebores or gives rise to natural variation. One of the easiest to cultivate, will reach flowering size in 2 - 3yrs, produces great deal of seed, giving rise to many large numbers of 'self setters' near the parent plant.  In view of this easy method, reproduction by division is rarely necessary.

Helleborus argutifolius - much more commonly known as the Corsican hellebore, Helleborus corsicus.  Similar to H. foetidus, but with much more deeply toothed edges to the leaves.  Another easy to grow species, even though its originates from a Mediterranean habitat, does however need to be grown in sunny position as it easily becomes leggy and top heavy, even in light shade.  Flowers appear February onward, pale green cup shaped flowers in large terminal clusters, which produce large numbers of seed and subsequent seedlings.

Helleborus lividus - a native of Majorca, is the least hardy of the group which produces overwintering stems.  Not reliably hardy it is advisable to always have pot grown seedlings in the safety of a frost free glasshouse overwinter to replace any losses.  Not so large as the previous two species, only reaching a height of 45cm.  Smaller heads of flowers, only about ten to the inflorescence, usually with a pink/purple stain.  Leaves also distinctive in comparison with H. argutifolius, in that they are heavily netted with their white veins. Readily hybridises with H. argutifolius, the hybrids produced being good garden plants, which although being very variable are all placed under the group name of H.x sternii.  Plants of this hybrid will if grown in isolation, breed reasonably true to type.

Helleborus niger - a member of the larger, stemless group of hellebores which overwinter as a basal cluster of leaves.  The most well known of the genus, H. niger or Christmas Rose, is a very variable species rarely flowering in time for Christmas, unless from a carefully selected strain planted in sheltered conditions.  Not a particularly robust grower, it is slow to build up a clump of sufficient size to split up.  Therefore although named selections such as 'Potter's Wheel' have been made over the years, they are rarely available through the nursery trade.

Easy to grow, best if they receive an annual top dressing of well rotted compost during winter months, and plenty of moisture throughout the summer months.  Once established, it is unwise to disturb, relying on collected seed or seedlings to increase stocks, but being a very variable species it will be necessary to control the parentage.

Has occasionally been crossed with H.argutifolius, the variable group of seedlings produced going under the name of H.x nigercors.  These like other interspecific hybrids such as H.x sternii, must then be sorted through and the best selections slowly built up by divisions.

Helleborus orientalis - a much more vigorous grower, quickly building up into a large clump.  Best known as the Lenten Rose.  Easy grower that does well in most reasonable soil conditions but is at its best in alkaline heavy soils under dappled shade.  An extremely variable species in the garden, there now being a great variety of almost true breeding strains available ranging from pale yellow and cream through various shades of pink and rose to deep purple/black.  Many selections are prettily marked with speckles, spots, blotches or have a dark central eye.  They may be nodding pendant flowers or boldly held almost upward facing, showing off either wavy edged, fully separated or completely rounded petals.  Flowers from January to April up to 45cm high.

An easily cultivated plant which is very hardy and long lived. Best on heavy limey soils in semi shade, but seems to do well on most soil types provided adequate moisture available throughout the summer months.  Responds well to deep cultivation plus incorporation of large amounts of well rotted manure.  Apply a top dressing of slow release fertilizer in spring as new growth appears, to increase vigour so improve the display in the following season.  Readily raised from seed, which must be sown soon after harvest, not allowing the seed to dry before sowing. These will if given good growing conditions produce a display of flowers after two growing seasons.  Easily propagated, the clumps being split up, although where divided down to individual growing points will take two years to resume flowering, but seed is by far the best way unless you have a highly desirable form.

Helleborus purpurascens - a very variable species, ranging from a dirty green/brown in the worst examples to purple violet via shades of violet and reddish purple in the sought after forms.  The cup or saucer shaped flowers appear rather early, during January through to March and therefore not so generous with seed production.  Flowers open as soon as they appear, gradually unfurling their stems until they reach their full height of up to 25cm, and 5 to 7cm across.  A native of woodlands and thickets in Romania the Ukraine and on through to E. Poland and Czechoslovakia.  Ideal conditions therefore are light shade, in a well drained leafmould rich soil.  Unfortunately not commonly available, clumps being slow to reach a splittable size, and the variable seedlings being not so prolifically produced.

 

Helleborus torquatus - the second purple flowered species, again from the Balkans often hybridising in the wild with other species such as the green flowered H. cyclophyllus and multifidus.  Although a attractive plant in its own right, is probably best represented as the parents of interspecific hybrids such as "Pluto", "Blue Wisp", "Black Knight" and "Ballard's Black".  Flowering from January through until March, some 20 to 40 cm high is not quite so tall as H. purpurascens.  Flower shape and size varying from upward facing saucers some 5cm across to downward facing cup shaped flowers some 3.5cm in diameter.  Colour varies from purple or violet black with a grey grape like bloom on the outside, to plain green or green/veined purple on the inner surfaces. Double forms have been found in wild populations, two selections of which are , "Dido" and "Aeneas". A plant of deciduous woodland, often near streams, not difficult if grown in partial shade, but responds well to liberal quantities of leafmould being dug in prior to planting.

Helleborus atrorubens - the third of the purple flowered species, again from the Balkans in N.W. Yugoslavia.  Frequently confused with a purple form of H. orientalis.  Differs from H. purpurascens in that the flowers are much smaller and the leaves smooth, whilst those of H. purpurascens are hairy.  Tall stems, some 20 -30cm high, carry up to 5 flowers on long branches, gives very different appearance to H. purpurascens, which opens its flowers as soon as they appear above ground. A very hardy species as are all hellebores from this area, does best in well drained alkaline soils, in partial shade.  Again like most of these woodland species, incorporating plenty of well rotted leafmould appears to be particularly beneficial, rather than peat.

Helleborus viridis - the most widespread of the green-flowered species, found throughout W. Europe, as far north as Great Britain down to N. Italy at its most southerly extreme.  A plant of deciduous woodland, often on heavy alkaline clay, is like many other Hellebores which overwinter as either a basal clump of leaves, or are completely deciduous best suited to open woodland plantings. Flowers are usually all green, 3.5 - 5cm in diameter, Feb - March, on stems up to 40cm high apparently a far more stable species than many other hellebores, but some hybridisation does take place in the wild.

H.cyclophus; H.multifidus; H.odorus -  this group which covers the majority of the remaining European species, are generally smaller than most previously detailed species.  All are green or yellow flowered, and scented like flowering currant. All have interesting spring foliage, covered with silver hairs as they unfurl at flowering time.  H. multifidus, is particularly attractive in that the foliage is very heavily dissected into masses of fine leaflets in the more select forms.  Unfortunately H.cyclophyllus and multifidus are easily damaged by winter frosts as they produce their new flowers and leaves.

SOME GENERAL HINTS

Hellebores are very tolerant and will grown in most soils as long as the ground is not extremely dry or waterlogged. they prefer a sheltered position in semi shade, (dense shade can reduce flowering) with a rich, moist, free draining soil. By planting your Hellebores on a sloping bed, you will naturally improve the drainage and make it much easier to look into the the flowers. Your soil preparation is most important. Hellebores are deep rooted and to flower at their best, they need plenty of nutrients. Dig your soil as deep as possible and mix in plenty of humus in the form of leaf mould, spent mushroom compost, or well rotted manure.

Mulch with spent mushroom compost in July-August, when next year's flower buds are being formed and again in late December. Remove the old faded flower stems, unless you require seed, to encourage next year's developing new growth. Cut out any damaged or diseased foliage and remove all remaining foliage from Ashwood Garden Hybrids and deciduous species in late December. This reduces the risk of infecting the new season's growth. Spray occasionally with a systemic fungicide and keep a look out for greenfly, slugs, and snails. Hellebores are generally long-lived plants. The regular mulching and feeding helps keep them healthy and free flowering. If your hellebores start to decline; you can lift and divide them just after flowering into single crowns. Prepare your soil well and replant, but be aware that the new divisions may take a few years to recover.

Several of the species, which do not produce overwintering woody stems, have a deciduous or semi-deciduous cluster of basal leaves best cleared away before the new foliage appears, in an attempt to reduce the incidence of leaf/black spot by burning the old diseased foliage.

The various leaf spot diseases generally only affect the less vigorous species, which often originate from the more southerly extremes of the hellebore range.  Suggested control measures, where general garden hygiene fails need to be based on sprays throughout the winter months at 3 week intervals with a systemic fungicide

Where the types with overwintering stems are grown eg. H. foetidus, it is advisable that the old flower stems are cut down to ground level once flowers are finished, unless it is intended to save seed.

Slugs and Snails can be a problem, especially if you are growing those that push the young flower buds directly up out of the ground, there are many means of attempting their control.

Planting is best carried out in spring as new growth appears, even though this may well cause loss of flowers that spring.  Take care to ensure planting at original planting depth, and ensure plenty of water until well established. To encourage continued vigour, the plants are best top dressed every winter, before tender new growth appears with a mulch of well-rotted compost or leafmould.

Large old clumps of the stemless species such as H. orientalis, tend to lose vigour with age these can possibly be rejuvenated by splitting them down to single crowns and replanted. The Christmas Rose, Helleborus niger, and a few other species flower very early and close to the ground, protection from weather and mud splashes with a soil covering mulch and overhead protection with cloches are useful if unsightly.

Seed Sowing

Sow Hellebore seed as soon as possible (preferably in July or August), in Supagro Seed Compost or in a mixture of 50% John Innes Seed Compost and 50% Multi-purpose Levington. Sow the seed thinly and cover with 6mm (1/4") layer of a mixture of 50% vermiculite and 50% washed grit. Leave the pot out in the open, but do not allow them to dry out. When germination has occurred, bring them into a cold frame or cool greenhouse, taking care against possible damage from slugs or mice. Prick out into small pots when the seed leaves are large enough to handle, using a mixture of two parts, (by bulk) of John Innes No.2, one part washed grit and one part of Levington. Pot on as required. Liquid feed regularly from about six weeks after potting on.

 

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Howard Drury, Horticultural Broadcaster, Speaker, Lecturer, Writer, Adviser and Consultant

Morningside, 8, Bagnell Road Kings Heath Birmingham B13 0SJ

Telephone 0121-443-3212 Fax 0121 441 2760 Mobile 07710-038-467

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The information given in this Fact Sheet is provided in good faith.  It is however of necessity general information and advice on the topic.  Howard Drury will not be under any liability in respect of the provision of such advice and information and you are strongly advised to seek independent advice on any particular gardening problems or queries you may have, preferably from experts who can (when appropriate) inspect the problem before providing advice.

(C) 2015. This material has been produced by Howard Drury and must not be reproduced in part or full physically or electronically without the written consent of Howard Drury, Kings Heath Birmingham, B13 0SJ. The only exception be to print a single copy for personal use from a downloaded file as part of www.thedrurys.com   website. Visit www.thedrurys.com or email for more information

JHD//23/05/2015

Parent Category: Gardening Fact Sheets
Category: Archived Fact Sheets 2014
Created: 10 June 2015
Last Updated: 10 June 2015
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