No garden should be without a winter-flowering daphne, so we've picked the best

What is that wonderful scent in the winter garden — so sweet, so strong and so hidden from sight? Well, it could be a viburnum, or one of those new mahonias, or even the shrubby honeysuckle Lonicera x purpusii. Nowadays, however, it is equally as likely to come from a plant of Daphne bholua, an essential staple of gardens in winter.

Daphne bholua is a recent addition to our gardens. Although first introduced from Nepal in the 1930s, it was not widely taken up by the nursery trade until the 1980s, when some of the best seedlings were given individual cultivar names. Yet it is no exaggeration to say that it has transformed our winter gardens. The first flowers may appear as early as November and the last well into March, sometime even April.

Daphne bholua had a reputation at first for not being reliably hardy, but, with thought for a position where it will be comfortable, it will prosper in almost any garden. It is one of those plants that has benefited not only from climate change, but also from the selection of forms that are naturally hardier. This reflects its mountain origins: in the wild, it is deciduous and hardier at higher altitudes, but evergreen and less hardy if collected from lower down the mountainside. Many modern selections are both hardy and evergreen, although, like most evergreen shrubs, it sheds some of its leaves in spring.

Sir Peter Smithers grew Daphne bholua so successfully in his super-temperate garden on Lake Lugano in the Swiss Alps that it seeded itself all too freely. He wondered whether, in years to come, it might be so prolific as to be designated a noxious weed. Arabella Lennox-Boyd brought seed back from a visit to Sir Peter and raised a great number of seedlings that now populate the woodland at her famous garden at Gresgarth Hall in Lancashire.

Almost all the plants of Daphne bholua in England today are descended from plants collected in the mountains of central Nepal, where they flourish in clearings in oak forests between 6,000ft and 10,000ft above sea level. The Nepalese have various medical uses for the shrub, but they also use it for making traditional lokta paper. However, the species has a much wider natural distribution and we will see a greater variation within the forms we find in our nurseries when more are introduced from such areas as Tibet, Myanmar and Vietnam.

Daphne bholua is widely reported to be happier on neutral or alkaline soils. That has not been my experience. I have grown it happily in chalk woodland, on greensand and on sandy clay — both acid in reaction. The truth is that it grows well on almost any soil that is never waterlogged in winter or likely to dry out in summer. Shelter from cold, dry wind is also important. Pinch out the young growths from time to time if you wish; this makes for a bushier plant. Daphnes do not need pruning, unless they have grown large enough to be a nuisance. Avoid hard pruning them, but, if you do so and the plant survives, it will produce useful suckers that you can cut off and grow on somewhere else — a useful trick because most are grown on their own roots.

Which are the best cultivars? Twenty years ago, I planted four in my winter garden: ‘Darjeeling’, ‘Gurkha’, ‘Jacqueline Postill’ and ‘Peter Smithers’. All flourished, but, five years later, I had no doubt that the best, all things considered, was ‘Jacqueline Postill’. That said, the differences between them are small — largely a question of the vigour of the plant and the colour of its flowers. All have an open shape with flexible stems and grow to about 8ft.

The RHS has given its Award of Garden Merit to two very fine forms that are readily available. The first is ‘Ghurka’, collected at 10,500ft and said to be particularly tolerant of low temperatures. Its dark, mauve-pink buds open to palest-pink flowers. The other is ‘Jacqueline Postill’, a seedling of ‘Ghurka’, with similar flowers, but perhaps slightly more of them, and rather more evergreen leaves that show them off.

Other good cultivars of Daphne bholua include: ‘Darjeeling’, an early flowerer, starting in November; ‘Limpsfield’, reliably evergreen; ‘Peter Smithers’, the best of Sir Peter’s collections in Nepal; and ‘Mary Rose’, with darker flowers. Karen Junker’s nursery in Somerset has recently introduced several new cultivars, too.

‘Jacqueline Postill’ is the most widely grown cultivar, but we can expect new forms in the years ahead that are even better — larger flowers, darker colours, denser growth (to produce even more flowers) and increased hardiness would all be regarded as improvements. Now, some breeders have also begun to cross it with other species, some with longer corollas or deeper colours. We can expect a flurry of new varieties over the next 10 years.

However, Daphne bholua is not the only species to flower in winter and fill the air with its penetrating sweet scent. D. mezereum, an English native, although not widespread, is tough, hardy and easy to grow. I can guarantee its hardiness because I have seen it flowering at 3,500ft in the Alps — first on the edge of pine-woods near Château d’Oex in Switzerland and then up the Roya valley in the Maritime Alps.

Daphne mezereum makes a sturdy shrub, typically 3ft–4ft high, which flowers on last year’s wood from mid February onwards. The flowers are a distinct deep pink, with a purplish tinge, and cling tightly to the stems, just below the apical buds that start into leaf at the same time as the flowers open. There is a pretty contrast between the pale, green, lanceolate leaves and the strong colour of the flowers encircling the stems. Their scent is very sweet and strong. It is a typical cottage-garden plant: I once saw it planted as a short hedge all along the front of a cottage garden in Wiltshire. The flowers are followed by round fruits, each with one seed in it — a ‘drupe’, say the botanists. They are quickly picked off by birds when they turn from green to bright red at the beginning of June.

There is also a white-flowered form known as Daphne mezereum f. alba, which is slightly more upright in habit, occasionally reaching as much as 5ft in height. Its fruits are bright yellow and no less attractive to birds. You need to collect seeds of both forms at the end of May when they are still green and sow them (best in a pot) immediately. I find I get 100% germination and that each form comes true from seed, probably because they are self-fertile. The seedlings are easy to grow on and should eventually be planted out in their permanent positions when they are about 4in in height — best done in May.

The only downside to most daphnes is that they are short lived, growing to their full height and flowering profusely — then suddenly dying, seemingly for no reason apart from their age. Daphne mezereum typically lives for 8–10 years and D. bholua up to 12 years. The wise gardener will always have spare seedlings to take their place. D. mezereum always produces a good crop of seeds from which to grow replacements and birds can be counted on to disperse them.

D. bholua also produces seeds — fewer, perhaps, but quite enough to grow on a crop from which to choose. If you look underneath an established plant of D. bholua, you will probably find quite a number of seedlings, ready to take over when their parent plant dies. The seedlings will be variable, but all will make good garden plants — there is no such thing as a disappointing daphne.

Why do they have such a strong, sweet scent if they flower at a time when there are so few insects to pollinate them? The answer is that the climate where Daphne bholua occurs in the wild is milder and there are always insects to do duty. It is, however, self-fertile, as is D. mezereum. Neither of them needs a pollinator to set good seed.

Why, therefore, do they both let out such a powerful scent, the sort that attracts insects from afar? Nobody knows. There is no end to the mysteries surrounding daphnes. Nor of their beauty.