Gardening: Winter wonders

Plants that flower come frost or snow? Sounds too good to be true. Nigel Colborn discovers the attraction of the hellebore

THERE IS more rejoicing in gardens over a single December bloom than an entire mid-summer flower border. How eagerly we pounce upon those tiny winter treasures - a first aconite, perhaps, or a twig of viburnum. And if a single winter flower, however puny or frail, can bring such joy, imagine what an orgy of delight awaits the hellebore enthusiast. Unlike the majority of off-season performers, these are as bold and prolific as summer roses. Nowadays their large, five-petalled flowers come in a rich variety of colours, from delicate green-tinged pink and white through shades of claret to deep aubergine.

At a time of year when no self-respecting bee would dream of emerging from its winter quarters, the whole process of blooming seems to be a total waste of energy as far as plants are concerned, but no one told the hellebores not to bother. Come the shortest day, the first Christmas roses open, waxy white with vivid golden stamens. And by late January, all the other members of the hellebore tribe will be blooming away with shocking recklessness, come frost or snow. It's a form of hibernian madness. Perhaps that's why the ancients thought hellebores could cure insanity - a sort of inverse Doctrine of Signatures where madness in a plant would cancel lunacy in a human.

Exotic hellebores were probably first brought to Britain for medicinal use, but since they are highly toxic - the word is derived from the Greek elein (to injure) and bora (food) - their use must have been pretty limited. We have two native species: stinking hellebore (Helleborus foetidus), which crops up in limestone woodland, and the rarer western form of green hellebore, H viridis subspecies occidentalis. Pretty and desirable though these natives are, it is the plants from the eastern Mediterranean and western Asia that are strongest on flower power. Of these, the best garden plants are hybrids which include, among others, H orientalis, a white- bloomed hellebore from western Caucasus, the brooding purple- and red- flowered H atrorubens, and H torquatus, whose flowers can be as blue- black as a raven's wing.

Do not expect to find avant-garde hellebores in a garden centre. Unlike roses, new varieties of which keep flooding into an already saturated market, hellebore numbers have been slow to bulk up. The most distinctive come from specialist producers, so you need to know where to shop. Specialist nurseries are no less accessible than garden centres, and many offer excellent mail-order service (you'll find details in The RHS Plantfinder (Dorling Kindersley, pounds 12.99).

Alternatively, go to one of the RHS flower shows in late winter. There, you can see the plants in flower and choose precisely what you want. And of course there is the bonus of enjoying the rest of the show - like a breath of spring in mid-winter, with all those snowdrops, crocuses, and camellias.

It was the Alpine nurseryman Walter Ingwersen who caused the first quantum leap in hellebore breeding, back in 1929. Nipping behind a rock in Serbia for a pee - so the story goes - he stumbled upon a form of Helleborus torquatus whose petals, instead of the usual greenish maroon, were slaty black. The gene for that unique colour has been used in a huge number of hellebore hybrids, not only darkening their hue but also lending flowers a distinctive satiny texture.

Since Ingwersen's chance discovery, a tiny cadre of talented breeders has enriched and expanded the range. In Worcestershire, Helen Ballard developed a series of named varieties in the 1970s with purer colours - clear pink, white with big purple spots and even primrose yellow. A decade later Elizabeth Strangman, at her tiny nursery near Hawkhurst, made further progress by developing a vigorous seed series. She too had a chance discovery, finding a double form of Helleborus torquatus growing wild in Yugoslavia, and used it to develop a number of double-flowered hybrids.

At Blackthorn nursery, Robin White has continued to broaden the choice. The spiky-leaved, almost shrubby Corsican hellebore, H argutifolius, was first crossed with the more familiar Christmas rose H niger in 1931, but White has used this and other breeding patterns to develop extraordinary crosses with flowers of pastel hues, suffused with green or coppery pink. The foliage of his hybrids is also distinctive, sometimes burnished-looking and often marbled with grey patterns. He too has developed a number of doubles and will be widening his plant range for years to come.

It's hardly surprising, since they are such engaging plants, that hellebores have inspired most great garden writers. Graham Stuart Thomas described the flowers as having a "thick, sculptured quality and rounded gracious outline, unsurpassed in the floral world". But for a modern view, Graham Rice - author with Elizabeth Strangman of The Gardener's Guide to Growing Hellebores (David & Charles, pounds 16.99) - offers the most inspirational ideas coupled with sound practical advice. When I cornered him at a recent flower show, the promise of a coffee was all it took to persuade him to talk hellebores.

"They don't just flower when they feel like it," he enthuses, "they flower anyway, regardless of weather, sometimes from Christmas to April." Specialists' plants they may be, but hellebores are far easier to grow than most perennials. "The secret," says Graham Rice, "is to get them off to a good start. They're often quite expensive to buy, so treat them as you would a new tree. Dig a hole, add compost, rotted manure or any kind of soil improver, plant them, and then leave them be." Neutral or limy soil suits hellebores best, though they will tolerate acid conditions. In the wild, most species grow along woodland margins in fairly rich, leafy soil which retains its moisture, so in a garden, mulching probably helps them to thrive and an occasional dressing of rotted manure will do no harm. If you want to propagate your plants, they can be lifted and divided. Late summer or early autumn is the best time for this, according to Graham Rice. "As the tops begin to go dormant, the roots start to grow," he says, so divide them in early September, when the root system is active.

"And don't be tempted just to remove small pieces from the edge of a mature plant," he adds. "It's far better to lift the whole root, split the plant into small divisions, give some away and plant the rest." It takes guts to murder your darlings, but the nurserymen do it that way. When I last bought named varieties, the plants cost the equivalent of a West End theatre ticket each, and were the size of a cigar stub! They took two years to bloom, but were well worth the wait.

The hellebores in my Lincolnshire garden seed copiously, so I never feel the need to lift or divide plants. "That's fine," Graham agrees, "but you have to select." "Oh, I do," I tell him. My technique is simple: I allow the plants to self-sow, and then root out any which have flowers of impure colour or irregular shape.

But Graham points out the weakness of my system. "If you let the bees do the pollinating, you have no control. Because petal spots tend to be dominant, over time you get a range of spotted flowers in middle colours. It is better to self-pollinate." He means something technical, like fertilising the flowers by hand with their own pollen. "Then you plant the resulting seedlings alongside the cabbages or wherever, and out of the whole line- up, you pick the single best plant."

Hmm ... unless you feel like setting aside the next few decades, it might be better to see what the professional breeders have to offer.

! Blackthorn Nursery, 01962 771 796 (no mail-order); Washfield Nursery, 01580 752 522 (no mail-order); Ashwood Nurseries Ltd, 01384 401 996. (Some suppliers may be closed for winter)

TOP TEN HELLEBORES

H foetidus `Wester Fliske'

Excellent form of our native stinking hellebore, with pewter leaves and reddish stems. Small green flowers with maroon edges

H argutifolius

The Corsican hellebore. Bold, prickly leaves; sprays of bright green flowers, 4cm (112in) across

H x sternii `Boughton Beauty'

Similar in habit to H argutifolius, but with a purple flush to the flowers and leaf stems

H torquatus

The species from Southern Europe with dark petal backs, but mysterious green interiors

H odorus

The source of all yellow to yellowish-green blooms

H atrorubens

Probably a subspecies of H orientalis. Deep red to purple, velvety blooms

H guttatus

Another orientalis type, with variable spotting or blotching of the petals

Orientalis hybrids

Rather a catch-all phrase, but you can find first-rate plants. Look for `Blackthorn Group'

H niger `Potter's Wheel'

Probably a seed series, rather than a true cultivar. Prolific bloomer with large, flat, pure-white flowers. `Ashwood Strain' is another excellent seed series

H cyclophyllus

Large blooms; evergreen foliage