Helleborus sternii 'Blackthorn Strain'

Helleborus sternii 'Blackthorn Strain' is a lovely species-cross developed by Robin and Sue White at their wonderful Blackthorn Nursery and introduced in 1989.
'Blackthorn Strain' is a carefully selected seed strain, the pink buds on purple stems open to creamy flowers backed with pink and green, the flowers turn delicate pink very shortly after opening.
The stems, petioles and often the anthers are an enchanting ripe berry rose, and the saw-toothed foliage is pewter-blue above, burgundy-grey beneath.

The Blackthorn Strain is a shorter plant than ordinary H x sternii growing to around 30 to 35cm (12 to 14in), but like its parent it is easy to grow and enjoys a sunny position in well-drained soil.
It flowers from late winter to early spring. Suitable for mixed border or woodland planting in groups. Plant in neutral to alkaline soil in sun or dappled shade.

Helleborus sternii 'Blackthorn Strain' is a species cross and has a rather complicated parentage; it was developed by crossing 'White Magic' with 'Louis Cobbett'

• Helleborus x sternii is itself a hybrid between green-flowered H. argutifolius, which gives the three-part fringed leaves and H. lividus with red highlights and smoky pink flowers but is relatively tender. First exhibited in 1947, it is named after the celebrated British plantsman Sir Frederick Stern.
• The small but prolific Helleborus 'White Magic' is a cross between H. niger, which gives the outward facing flowers, and H. orientalis.
• H. niger 'Louis Cobbett' raised by its namesake at Cambridge prior to 1962 is one of the earliest varieties to bloom, with pinkish blooms and maroon stems.

Sowing: Sow seeds immediately upon receipt, at any time of year.
Hellebore seeds are collected in early summer. If they are planted in the first few months, they will germinate quickly in around 30 days. Once the weather starts to get cold in autumn, they will go dormant and delay germination until the weather warms up in the spring and conditions are more favourable.
Text books quote germination as ‘irregular’ and advise 30 to 545 days, in my experience 30 to 180 days is usual, dependent on the time of year that they are planted.

Sow in moist John Innes seed compost or something similar, place each container in a polythene bag or place a plastic lid onto the container. Place in a cold greenhouse or cold frame. The compost should be kept moist but not wet at all times.
Some of the seeds will germinate straight away, some during the spring and summer, any remaining seeds may lay dormant until the following spring. If any seeds do not germinate in the spring keep them in cool moist conditions throughout the summer.
As each seed germinates transplant it almost immediately into its own 7.5cm (3in) pot to grow on. These strong plants need more nutrients and water than small cells can provide. Keep seedlings in a well lit place, but out of direct sun.
Gradually acclimatise to outdoor conditions for 10 to 15 days before planting out, space 30cm (12in) apart.

Hastening Germination:
Seeds can be left to go through the seasons naturally or germination hastened by “Stratifying” (imitating the seasons)
Soak and sow seeds as above and leave for six weeks. Transplant any seedlings that have germinated. After 6 weeks chill the remaining seeds: put the tray into the refrigerator at -4°C to +4°C (24-39°F), or somewhere with a similar temperature for six to eight weeks. Then remove to around 10°C (50°F)
Prick out each seedling as it becomes large enough to handle, transplant into 7.5cm (3in) pots or trays. Gradually acclimatise to outdoor conditions for 10 to 15 days before planting out, space 30cm (12in) apart.

Cultivation:
If your soil is high in organic matter, and has a fairly good water holding capacity, then Hellebores will grow wonderfully in your garden. Hellebores have a deep growing root system and they will benefit greatly if the area is prepared before planting. Double digging the area (digging out one shovel depth of soil, and then digging up the second layer of soil, and then putting the top layer back on and digging it all together) with additional organic matter is of great advantage. Add some sharp sand if your soil is especially heavy and sticky.
Hellebores prefer a neutral to alkaline soil Ph (they will grow in a slightly acidic Ph soil too). Mushroom compost or well decomposed garden compost is good as an additive.
Hellebores are Mediterranean plants, and they prefer moist but well drained soil, a period of drying our between watering is of great benefit to good overall growth.

Cut down flowers as they are over to encourage basal growth or leave to set seed. Once the plant has flowered and new foliage shows signs of emerging, you can cut away the old leaves.
Hellebores will set seed with new plants coming up around the main plant. Seedlings are easy to transplant to other parts of the garden.
Plants resent root disturbance and are slow to re-establish when divided and are best left undisturbed for 6 to 7 years before being divided. Should you ever have to move a plant, dig a ball of earth around its roots as you would for a shrub.
Do not use chemical fertilisers as it is extremely sensitive to them and burns easily. Stick to dressing with compost or aged manure in the autumn.

Plant Uses:
Cottage/Informal Garden, Flower Arranging, Flowers Borders and Beds or Under-planting roses and shrubs.
As a cut flower, these flowers float on water and will stay fresh for many days. Take care when handling the plant as it may cause skin irritation or allergic reaction.

Origin:
A genus of some 15 species native mostly to southern Europe. Hellebous niger is a native of central and eastern Europe and especially the Balkans. It is found mainly in high altitude woodlands that are blanketed by snow in winter.
To the botanist the features which distinguish H. niger from other species are the undivided bracts, the noticeably prominent elaiosome (see below) on the seeds and the smooth pollen grains.
To the gardener the large, pure white, waxy flowers carried singly on stiff upright stems and the dark, leathery, almost untoothed foliage make it easily distinguishable.

An Explanation:
Elaiosomes (From the Greek élaion meaning "oil" and sóma meaning "body") are fleshy structures that are attached to the seeds of many plant species. The elaiosome is rich in lipids and proteins, and may be variously shaped. Many plants have elaiosomes to attract ants, which take the seed to their nest and feed the elaiosome to their larvae.
After the larvae have consumed the elaiosome, the ants take the seed to their waste disposal area, which is rich in nutrients from the ant frass and dead bodies, where the seeds germinate. This type of seed dispersal is termed myrmecochory from the Greek "ant" (myrmex) and "dispersal" (kore). This type of symbiotic relationship appears to be mutualistic, as the plant benefits because its seeds are dispersed to favourable germination sites, and also because it is planted (carried underground) by the ants.

Nomenclature:
The name Hellebore is taken from the Greek helleboros.
Helleborus niger is commonly called the Christmas rose, an old legend says that it sprouted in the snow from the tears of a young girl who had no gift to give the Christ child in Bethlehem.
Its common names of Lenten or Christmas Rose also refer to its blooming period.
Despite the species name “niger” meaning black, it bears an abundance of pure white flowers. The name
refers to the colour of the roots; it was applied in 1753, although the plant had previously been long cultivated in the UK even then.
Other common names are Clove-tongue, St Agnes' Rose, Christmas Plant, Christopher's Herb, Christ's Herb, Bear's Foot, Brumal Rose.
Helleborus are member of the genus Ranunculaceae, the Buttercup family.