Helleborus - A flowering plant for the middle of winter

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    Hellebores, Winter Hardy Shade

    Perennials for the Woodland Garden

    A Primer on the Genus Helleborus

    By Tony Avent

    Plant Delights Nursery, Inc.

    www.plantdelights.com

    9241 Sauls Road

    Raleigh, NC 27603

    919.772.4794

    June 2010

    http://www.plantdelights.com/http://www.plantdelights.com/
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    There are few perennials that can rival the seasonal interest ofhellebores ... often called

    Christmas or Lenten Rose. These staples of the winter garden are among the most

    coveted of garden plants by those who know them, yet they are still relatively unknownoutside of plant enthusiast circles. Because they don't flower quickly from seed and often

    finish flowering before most folks visit garden centers, hellebores are rarely found at the

    lower end mass merchants.

    Hellebores have long been grown in gardens, although originally for their medicinal

    properties. Hellebores are filled with alkaloid toxins and have been used both as a poisonand a purgative. Because of their toxicity,hellebores are prized as "deer resistant" garden

    plants for areas suffering from deer or similar wildlife pressures.

    A true testimonial for the durability ofhelleboresare those growing at the old Raleighgarden of NC's famed garden writer, the late Elizabeth Lawrence. Her Raleigh home,

    from which she moved in the 1940's, is still filled with wonderful clumps of Helleborus x

    hybridus, despite being used as a fraternity house for several decades!

    Hellebores are renowned for their tolerance of drought and neglect, although they truly

    thrive when grown in a moist, but well-drained soil. They are very sensitive to poordrainage, so be sure your soil drains well. Becausehellebores naturally become very

    rootbound in containers, it is important when container-grown plants are put in the

    ground, to remove the potting mix and loosen the roots. This will make it much easier to

    keep the hellebore roots moist until they are well-established. If you keep your plants incontainers, be aware they are very heavy consumers of water when actively growing in

    the fall and spring months, but not when they go into a non-active growth state during the

    heat of summer.

    Hellebores are primarily European natives, growing in open meadows in Bosnia, Croatia,

    Slovenia, Turkey, Greece, Italy, and even China, where the deciduous species Helleborusthibetanus can be found. While naturally a full sun plant, helleboresmake superb

    specimens for the light woodland garden. We salute UK plant explorer, Will McLewin,

    who, along with other hellebore enthusiasts, risks his life to regularly trek through theseregions gathering hellebore seed and researching the genus with a rarely-seen dedication.

    Hellebores are often found native in alkaline soils, but adapt without a blink to acid

    woodland soils. As for fertility, hellebores need nothing more than a rich, highly organicsoil, amended as needed, with an organic fertilizer. For the lazy gardener, I have seen

    spectacular gardens ofhellebores that have never seen a drop of commercial fertilizer.

    Hellebores are split into two basic groups, acaulescent (without stems) and caulescent

    (with stems). The caulescent species include Helleborus argutifolius, Helleborus foetidus,

    and Helleborus lividus. The acaulescent species include Helleborus orientalis, Helleborusniger, Helleborus purpurascens, Helleborus viridis, Helleborus atrorubens, and all others.

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    Acaulescent (Non-Stalked) Helleborus Species

    One of my favorite acaulescent species is the Christmas rose, Helleborus niger. Whilerumored to be difficult to grow in the South, the large clumps in both my garden and

    others throughout the South confirm this rumor to be unfounded. Indeed, Helleborus

    niger is not as easy to grow as the Helleborus x hybridus, but still easy enough for mostgardeners. Helleborus niger has darker green and much smoother leaves than the H.

    orientalis hybrids and begins flowering much earlier. For us (NC), Helleborus niger is

    usually in flower by late December or early January. The flowers in this species are purewhite, and arise similar to Helleborus x hybridus. We have found Helleborus niger ssp.

    macranthus and the Helleborus niger 'Nell Lewis' strain, which often flowers in one year

    from seed, to be some of the best. Available now are selected early flowering, vigorous

    clones such as Helleborus niger 'HGC Josef Lemper' PP 15,615 and Helleborus niger'Jacob' PP 17,799 both from Germany's Heuger Hellebores, along with new double

    flowering clones like Helleborus niger 'Double Fantasy'.

    While everyone knows the name Helleborus orientalis, virtually no true Helleborusorientalis is actually grown outside of a few plant collectors' gardens. Most plants grown

    under this name are in fact interspecific garden hybrids. Of the other acaulescent species,Helleborus purpurascens (purple flowers), Helleborus atrorubens (very early purple

    flowers), and Helleborus viridis (green flowers) are good easy-to-grow choices, although

    none make nearly the spectacular garden specimens as do interspecific hybrids.

    Helleborus croaticus has very cute small flowers and some forms of Helleborusmultifidus have narrow leaves that warrant growing it even if it didn't flower. Unlike

    Helleborus niger and Helleborus orientalis, many of these species are often deciduous, so

    don't panic when they disappear in winter.

    Acaulescent Helleborushybrids

    The most commonly known acaulescent species name is Helleborus orientalis, the Lenten

    Rose. As mentioned earlier, these are actually complex hybrids involving an array of

    acaulescent species. These plants are correctly called Helleborus x hybridus. As a rule,Helleborus x hybridus are generally much more vigorous than the straight species.

    Each plant of Helleborus x hybridus makes a 2' wide by 1' tall clump of thick evergreen

    hand shaped leaves. In late winter, the 12"-18" tall flower spikes emerge from theunderground rhizome. As the flower spike tops the leaves (which flatten out in the

    winter), it branches, producing a cluster of silver-dollar-sized flowers. Actually, what we

    call flowers are not petals, but a modified calyx. This accounts for the seeming longevity(up to 3 months) of the hellebore "flowers". We recommend waiting to remove the old

    foliage until just before the flowers emerge for a better floral show. The foliage serves to

    protect the developing flower buds and to keep them cool and therefore delayed. If thefoliage is removed too early in the season, the developing flower buds may break too

    early and be susceptible to damage by late spring hard freezes.

    It is the flower colors of Helleborus x hybridus that enthrall plant collectors, as each one

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    is dramatically different. The basic colors range from black-purple to red-purple, to

    white, pink, and even yellow .... all depending on the parentage of the species. The

    patterns on the blooms add even more fun, with breeders working to bring differentcolored speckles both to the center and edge of the flowers. Hellebore breeders are also

    working on flower shape ... some opting for cupped flowers, while others work towards

    breeding large, flat, open flowers. Some breeders prefer up-facing flowers, while othersprefer the natural bell-like form, where the colors are only seen on the back of the

    flowers. The latest creations are double flowered and anemone-flowered forms, where a

    second row of petals makes an attractive collar inside the large calyx.

    Purchasing named varieties ofhelleboreshas always been a difficult task for gardeners.

    Most of the early hellebore work was done overseas by folks such as the late Helen

    Ballard of Germany, Elizabeth Strangman of Washfield Nursery, John Massey and theAshwood Nursery breeders of the UK, and the late Eric Smith, also from the UK. US

    breeding has made great advances thanks to the work of Glenn Withey and Charles Price

    of Washington, Dan Hinkley of Washington, Ernie and Marietta O.Byrne of Oregon,

    David Culp of Pennsylvania, and Dick and Judith Tyler of Virginia.

    When a hellebore breeder would develop a nice variety, everyone would want a division.While hellebores can be divided, the process is never going to be viable on a large

    commercial basis. This prompts both high prices, and unscrupulous nurserymen selling

    seedlings as "true cultivars". In fact, each seedling is different, and only in well-

    developed seed strains does the flower color of the seedling come close to matching thatof the parent.

    Only in the past few years have more growers started to sellhellebores by known flowercolor. This is done either by divisions or tissue culture, where all the plants are identical,

    or by growing and flowering a large batch of seedlings and then sorting them by color.

    Obviously, the time involved in this process (2-3 years from seed to flower) will bereflected in the price. For a slightly lower cost, you can buy unflowered seedlings, which

    thanks to better inbreeding, good strains should have a higher percentage of colors similar

    to their parents. Tissue culture is a fairly recent breakthrough with Helleborus x hybridus,but one destined to change the availability of specially-selected helleboresas more and

    more selections go under the knife. When purchasing a tissue-cultured hellebore, you

    need to remember offspring will still not come true from seed. If you want to maintain

    the color integrity of a particular clump, be sure to remove the developing seed to keepthem from sprouting around your parent plant.

    For years, it was assumed that Helleborus niger was so far out of the hellebore family treethat it could not be crossed with any of the other acaulescent species. That all changed in

    2000 with the introduction of Helleborus 'Snow White' from Japan, the first cross of

    Helleborus niger and Helleborus x hybridus. While 'Snow White' is sterile for us, and thecrossing of Helleborus niger and other acaulescent species remains difficult, there are

    other similar hybrids in the pipeline, which add more colors to the range of this early-

    flowering hybrid group.

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    Caulescent (Upright-stalked) Helleborus Species

    I am also a big fan of the caulescent (stemmed) species. My favorite is certainlyHelleborus foetidus, the so called "stinking hellebore". While folks often expect smelly

    flowers, the only part of the plant that is fetid are the leaves, which leave an unpleasant

    odor on your hands if you fondle yourhelleborestoo much.

    Helleborus foetidus has very dark evergreen leaves with long "fingers" which clothe the

    18-24" tall stems. As a background plant to hostas and ferns in the summer garden,Helleborus foetidus is marvelous. As the perennials of summer go to sleep, the evergreen

    clumps of Helleborus foetidus remain and become the focus of the winter garden. In fall,

    the flowering stalks emerge, opening from October to around the first of the year with 1'

    tall spikes of green bell-like flowers. These flowers remain attractive until early spring.

    Thanks to keen gardeners around the world, there are now many different forms of

    Helleborus foetidus available. The most popular is Helleborus foetidus 'Wester Flisk', an

    attractive plant with red stems and slatey green leaves.Helleborus foetidus 'Red Silver'Strain (Northwest Garden and Nursery) and 'Piccadilly' (Piccadilly Farms) are similar

    strains. Helleborus 'Green Giant' is much larger and can often reach 3' tall. Other formsboast more cutleaf foliage, dark black leaves, and a variety of other unique

    characteristics. One of the most unique is Helleborus foetidus 'Chedglow', displaying

    golden foliage and color that runs into the flower stalk. Helleborus foetidus is a short-

    lived perennial with a life expectancy of 2-3 years. Fortunately, it is a prolific seeder andonce your plant of Helleborus foetidus sets seed, you should never be without this gem

    again.

    Helleborus argutifolius is also a worthwhile garden addition. Making a 2' tall x 2' wide

    evergreen clump, it is adorned with very serrate, trifoliate leaves. In late winter, it is

    topped with stalks of creamy light green flowers. When winter temperatures drop below15F, the foliage may become damaged, but the plant resprouts well when cut back to the

    ground in spring. One of the few selections in the trade is the clonally reproduced

    Helleborus argutifolius 'Silver Lace' with stunning silvery pewter leaves, topped withgreen flowers.

    The most tender of the caulescent species is also the most beautiful, Helleborus lividus

    from Spain. The silver and green patterned leaves form a 2' wide clump, topped withgreen and pink flowers that would make any gardener covet this gem. Although it has

    been hardy in our garden for 15 years, we are at the northernmost end of its range since it

    must be grown where it will receive good summer heat. The only named cultivar ofHelleborus lividus is Helleborus lividus 'White Marble' that boasts white veins, lacking

    the red pigment more typical of the species.

    Caulescent Hellebore Hybrids

    For those a bit further north, try the hybrid Helleborus x sternii (Helleborus argutifolius x

    Helleborus lividus). This hybrid combines the beauty of Helleborus lividus foliage with

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    the upright growth habit of Helleborus argutifolius. Both seed strains and tissue cultured

    clonal selections are available. Like Helleborus argutifolius, temperatures below 15

    degrees F can damage the old foliage. Popular seed strain favorites include Helleborus'Boughton Beauty' (silver grey leaves with pink flushed stems), Helleborus x sternii

    'Blackthorn' (green leaves with grey veins and pink stems), and Helleborus 'Rachel'

    (glossy green leaves with silver veins). Clonal selections include Helleborus x sternii'Pacific Frost' (white speckled leaves), Helleborus x sternii 'Fire and Ice' (white speckled

    leaves), Helleborus x sternii 'Hot Flash' PPAF (silver and green leaves with red veins),

    and Helleborus 'Winter's Grace' (silver leaves and pink stems). Helleborus foetidus has sofar been impossible to cross with other species, but I'm sure it's only a matter of time until

    breeders are successful.

    Acaulescent/Caulescent Helleborus Hybrids

    For many years, it was thought the acaulescent and caulescent species could not be

    hybridized, but we now know this was incorrect. Helleborus niger can be readily crossed

    with Helleborus argutifolius, resulting in the virtually sterile Helleborus x nigercors. Thefoliage of these hybrids resembles Helleborus niger, but the abundance of flowers is

    much greater ... often over 100 per plant. There are now several clonal tissue culturedselections of Helleborus x nigercors including Helleborus 'Valentine Green' (green leaves

    and creamy flowers), Helleborus 'Honeyhill Joy' (green leaves and creamy flowers),

    Helleborus x nigercors 'Green Heron' (green leaves and green flowers), Helleborus x

    nigercors 'White Beauty(green leaves and white flowers), Helleborus x nigercors 'SnowLove' PPAF (green leaves and white flowers), and Helleborus x nigercors 'HGC Green

    Corsican' PP #15,641 (green leaves and cream flowers).

    Helleborus niger has also been crossed with Helleborus x sternii resulting in Helleborus x

    ericsmithii (aka: Helleborus x nigristern), named for the late UK plant breeder of hosta

    fame, Eric Smith. There are several nice forms of this cross including Helleborus xericsmithii 'Pink Beauty' (green leaves with pink/green flowers), Helleborus x ericsmithii

    'Winter Moonbeam' (nice silver veined leaves and cream and purple tinted flowers),

    Helleborus x ericsmithii 'Candy Love' PP 19,413 (green leaves and cream to pinkflowers), Helleborus x ericsmithii 'HGC Silvermoon' PP15,639 (silver leaves and creamy

    flowers), and Helleborus x nigersmithii 'Walhelivor' PP 16,199 (also known by the non-

    cultivar name Helleborus 'Ivory Prince', which has grey green leaves and creamy pink

    flowers).

    The rarest of the Helleborus niger hybrids is Helleborus x ballardiae (aka: Helleborus x

    nigriliv), which is derived from a cross of Helleborus niger and Helleborus lividus. To thebest of our knowledge, Helleborus 'December Dawn' is the only commercial cultivar of

    this cross, although it is not yet widely available.

    Helleborus Propagation

    If you want to propagate your own hellebores, growing them from seed is the easiest and

    most common way. Hellebore seeds ripen in May and June, and must be sown fresh since

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    the viability of hellebore seed decreases rapidly in storage. Once the seed is ripe, it can be

    surface-sown in a pot of potting soil or in a well-prepared outdoor seedbed ... do not

    cover the seed. Keep the soil slightly moist during the summer and be sure to leave thepot outdoors in fall. Once the seed has been subjected to adequate cold temperatures, it

    will begin to sprout. The chilling canoccur in a refrigerator, provided you remember to

    remove the seeds when they begin to sprout and you have an understanding spouse.Helleborus lividus and Helleborus x sternii are some of the first seed to sprout, followed

    by Helleborus foetidus, then Helleborus x hybridus. In the garden, you can also simply

    allow the seed to fall to the ground, where it will germinate the following lateFebruary/early March. It is possible for a few Helleborus to flower within 12 months of

    the seed germinating under good container culture, but 2 years is more typical. Seed

    allowed to fall in the garden will usually take at least 3 years to flower. The long

    production time and accompanying nursery-space cost is why flowering-sizedhelleboreswill be priced much higher than non-flowering plants.

    As is the case with humans, hellebore offspring do not always resemble their parents. In

    the garden, Helleborus x hybridus will have the best chance of being similar to the parentif similar colors are planted together in the garden. We find differing colors need to be

    planted at least 25' apart to keep the colors from blending thanks to the work of bees.While color blending can yield a few interesting seedlings, it also yields quite a few

    muddy colored hybrids.

    If you have a particular selection (clone) of Helleborus x hybridus you really like, youcan also divide the clump, but timing is critical. The ideal time to divide is during the fall

    or winter, although it is also possible to divide plants around flowering time. Clumps can

    be lifted, divided and reset or can be divided while in the ground using a sharp knife orshovel. I don't recommend dividing them to single divisions, which is rarely successful.

    Where to See Hellebores

    Until recently, most Helleborus x hybridus have been sold as unflowered seedlings. This

    began to change in the early 2000's when tissue-cultured plants hit the market. Unlessyou are purchasing a cloned tissue-cultured plant, you must visit a nursery when the

    helleboresare in flower to select the color you desire, although the first US nursery to

    offer this option on a large scale was Piccadilly Farms in Georgia. Several of us have

    followed suit, so there are now many options to see yourhellebores in bloom beforepurchasing them. Our hellebore open house days are usually held in late February/early

    March in conjunction with our friends at Pine Knot Nursery in Virginia. If you are on the

    West Coast, don't miss the hellebore open days at Northwest Garden Nursery in Oregon,and if you can make it to the UK, the hellebore open days at Ashwood Nursery are not to

    be missed.

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    Reference

    For further reference on hellebores, we recommend the following books:

    The Gardeners Guide to Growing Hellebores by Graham Rice and Elizabeth Strangman

    (Timber Press)

    Hellebores by Brian Matthew (Alpine Garden Society, UK)

    Hellebores, A Comprehensive Guide by Cole Burrell and Judith Tyler (Timber Press)