Christmas Rose – Helleborus niger

Just two simple pictures today – most forms of Hellebore really get into their stride in very early Spring – and some continue long into Summer. In the vanguard are these delightful pure white forms of Helleborus niger, the Christmas Rose. Plenty of time for the rich ruffles of plum, chocolate and slate that come later, let’s enjoy these pristine crystalline whites now and in the weeks to come in our gardens. Ideal container plants as Val Bourne has found (see article).

These photographs taken at RHS Wisley on Christmas Eve.

The superlative Graham Rice writes further at http://www.grahamrice.com/hellebore/species/niger/index.html

The sainted Val Bourne, writing in The Telegraph adds more at  http://www.telegraph.co.uk/gardening/howtogrow/3316376/A-wonderful-sight-in-the-bleak-mid-winter.html

Val Bourne (The Telegraph 27th December 2003)

The largest flowers of any hellebore belong to the Christmas rose, Helleborus niger. Their white, perfectly formed blooms can measure more than 4in in diameter and make a wonderful sight in bleakest mid-winter. When, that is, they flower properly.

For years I tried to grow them. They would send up a few flowers, often in March, which never seemed to lift their heads above soil level. There they languished – splattered, muddy and hopelessly unspectacular.

Nothing worked. I tried dappled shade, full sun, deep shade, dry shade and damp: all the while my oriental hellebores (H. x hybridus) grew and flowered their socks off.

Then, five years ago, I experimented by planting a small seed-raised Christmas rose in a large terracotta container with skimmias and spring bulbs. Over the next three years this sent up masses of flowers on strong stems held well above the leaves. Now I grow all my H. niger in pots at least 12in deep, and place them close to doorways and paths. Every year I buy more young plants, costing about £1.99 each, to add to my collection.

My original Christmas rose grew because I had unwittingly given it ideal conditions: a deep root run, gritty, well-drained compost and a dry position away from the worst of winter rain. This is close to the natural habitat of H. niger, which grows on high ground in Switzerland, southern Germany, Austria, Slovenia, Croatia and northern Italy, in wooded and open situations. Winter rain falls as snow on high ground, which means that the crown of the plant doesn’t endure the sort of wet we experience in Britain, which does not suit H. niger.

Black spot

Pot-grown Christmas roses also escape black spot – Coniothyrium hellebori – which can be a big problem for them. The disease commonly affects all hellebore foliage and occurs when water-borne spores travel between the blackened leaves and the ground – and back again. Pot-grown hellebores, raised well above soil level, do not suffer in the same way.

To prevent the spread of black spot always take off the top inch of soil from newly bought hellebores, even if they look healthy, and replace it with fresh compost. This will remove any troublesome spores that may be lingering in the pot. Nursery stock is invariably sprayed, but you shouldn’t need to do this if you follow this regime. Remove leaves that show signs of the disease whenever you see them and take off every leaf in early December, so that only the emerging buds are left.

Forcing Christmas roses

Resourceful Victorian head gardeners lifted entire plants of Helleborus niger in September and brought them under glass to force them into flower for December 25. Despite their name, Christmas roses usually wait until the new year to flower. The big danger of growing any hellebore in a greenhouse during our damp winters is botrytis. This grey mould appears when the air- flow is restricted, so make sure that you ventilate your glasshouse or cold frame daily.

Potting young Christmas roses

By now, garden centres and nurseries will have plenty of young, seed-raised plants for sale. Once bought and taken home, examine the foliage carefully and remove all dead, blackened or yellow leaves (1), leaving the healthy leaves intact.

Be sure to examine the root system. A healthy plant will have an unbroken network of thick white roots. If the root system is poor, loosen the soil to check for vine-weevil grubs.

Fill a deep rose pot to within 5in of the top using a mix of one third coarse grit to two-thirds soil-based compost (John Innes No 3 is ideal for these greedy feeders) (2). Place the hellebore on top of the soil and fill round the plant (3), adding a top-dressing of coarse grit (4). This and the gritty compost will help to deter vine weevils from attacking the roots and improve drainage.

Place your pots in the lee of a house for a few weeks to avoid waterlogging by winter rain.

Dead-heading

Newly rooted young plants should flower the following winter. Be sure to dead-head the faded flowers, which turn a pale-pink colour as they age, to encourage an unbroken succession of blooms. All the hellobore’s energy needs to go into producing a strong plant, not into seeds.

Repotting mature Christmas roses

After flowering, place the plants in a cold frame or somewhere out of full sun in your garden. Keep them just moist during very dry summers, giving them a dormant period. Take them out of the frame in September and check the leaves, removing any chlorotic (yellow) or diseased leaves. Upend the plants and check the root system again: by now the roots should be at the edge of the pot. Using a half grit and half soil-based compost mixture transfer them into a slightly larger pot. Add another layer of grit to deter weevil damage.

Planting companions

Large pots of Christmas roses look as good as single specimens and do well throughout the winter placed against any door, regardless of aspect.

Mixed containers look most effective if they include one Christmas rose mixed with the glossy leaves of ivies, evergreen euonymus and varieties of Skimmia japonica. Deep-red outdoor cyclamen look particularly gorgeous with the white flowers