Daphnes for Scent and Colour
Anyone with even a passing knowledge of plants knows that daphnes have wonderfully fragrant flowers. And because some of them - usually the most scented - flower in winter, they're the sort of must-have plants that are usually among the first planted in any new garden.
There are around 50 species of Daphne, many of which are choice garden specimens. They are widespread lot, ranging from Europe and North Africa to temperate and subtropical Asia. Most of them are evergreen or nearly so, but a few are deciduous, often flowering before the foliage expands.
The plant everyone calls daphne is Daphne odora, particularly the cultivar 'Leucantha' , which is often misspelt 'Leucanthe' . This shrub, a native of China and Japan, sells in vast numbers, mainly on the strength of its perfume, but also because it's a reasonably hardy evergreen bush. It grows to around 1.5m tall with leathery, deep green leaves up to 80mm long. From mid-winter on into spring it produces clusters of small, starry, pale pink flowers. Several flower and foliage forms are available and the variety with yellow-edged leaves, 'Variegata' (sometimes called 'Aureomarginata' ), is often hardier and easier to grow than the species.
Daphne odora can be quite particular about soil conditions and is slightly frost tender in cold winter areas. It does best in cool, moist, humus enriched, well-drained, acid soil in sun or light shade. Work in plenty of compost or similar organic matter - it's impossible to use too much - and feed regularly with liquid fertilisers and an occasional side dressing of acid fertiliser. Kept healthy, D. odora develops quickly and is attractive even without flowers, but it isn't a long-lived bush. You can expect to have to replace it at least every 8-10 years.
Because daphnes are so popular, nurseries propagate thousands of them every year. For many years the plants were nearly all cutting-raised and with repeated propagation by this method the cutting stocks declined and became badly infected with viral diseases that were transmitted to their progeny. Around fifteen years ago Daphne odora 'Leucantha' was refreshed by producing new plants by tissue culture, thereby eliminating most of the disease problems. At the time, the improved appearance of these virus-free "high-health" plants was remarkable. Although since then new batches of tissue cultured plants have been introduced, many of the original high-health daphnes were used as cutting stock and now these plants are showing viral problems. When buying 'Leucantha' try to ensure that you get a tissue cultured plant or a first or second generation cutting from cultured stock.
Several other species are similar in appearance to Daphne odora and are well worth growing as slightly different alternatives to what everyone else has. Of these, Daphne bholua and Daphne laureola are the most commonly available.
Daphne bholua occurs in both deciduous and evergreen forms, but here they all seem to behave as semi-evergreens (or semi-deciduous if you like). It is shrub up to 3m tall, sometimes rather narrow and open in habit, that like Daphne odora flowers in winter and spring. The flowers are strongly scented, white-tinged-pink and open from deep pink buds. Black fruits (drupes) follow the flowers.
First classified in 1825 but slow to enter cultivation, it is one of a group of four species known as paper daphnes because in their home range paper and ropes were made from their bark. It was first recorded in gardens in 1938, but didn't really become at all widely grown until the late 1960s to mid 70s.
Native to the eastern Himalayas, it is somewhat tougher than Daphne odora under New Zealand conditions. Though strangely, British references often rate it as slightly less hardy. Whatever the reason for its local success, just be happy to know that in most of our gardens it thrives.
Daphne bholua is difficult to raise from cuttings and although it can be grafted, seed is the best method of propagation. The seed germinates well and while the seedlings are slow to start into strong growth, they gain vigour with age and usually flower in their fourth year.When it's not in flower it would be easy to mistake the Spurge laurel (Daphne laureola) for a very heavily foliaged form of Daphne odora. However, this European and western Asian native is a much tougher and more adaptable plant. It grows to about 1.5m tall and has lush, deep green, evergreen foliage that is capable of tolerating deep shade. Its flowers are fragrant and because they are small and rather a pale green shade, it's often the scent that strikes one first, locating the flowers by sight taking a little longer.
If only for its value as a foliage plant for dull corners, Daphne laureola could be much more widely grown. The scent is really just a bonus.
You may also see Daphne pontica from the Balkans and western Asia. It too has glossy, deep green, leathery leaves and fragrant flowers, sometimes very pale pink to white but usually a light green shade and fragrant.
Iron chlorosis is a potential problem with all of these dark green, large-leaved, evergreen daphnes. When chlorotic, their foliage yellows, though the veins tend to remain green. The answer is to mulch well and to occasionally drench the soil with an iron sulphate or iron chelates solution. Use iron sulphate at the rate of around a teaspoon per litre of water.
Other daphnes are quite different and may not be what you'd expect if you're familiar with only Daphne odora. The most widely grown, Daphne burkwoodii, isn't a species but a hybrid between Daphne cneorum and Daphne caucasica. It is a twiggy, densely foliaged evergreen or semi-evergreen bush with matt mid-green foliage and masses of small, fragrant, pink flowers in spring. The variegated foliage forms, such as 'Carol Mackie', are probably more widely grown than the plain species and have the advantage of being more colourful when not in flower.
Several other species, such as Daphne cneorum, Daphne retusa, Daphne collina and Daphne neapolitana are similar in general appearance but vary in size and flower colour. The smallest of the readily available species is the rock daphne (Daphne cneorum). It grows to about 20cm high 60cm wide and has the reputation of being a difficult plant to cultivate well, although it's definitely worth trying. The form 'Eximea' is a sturdier than the species. Excellent drainage, shelter from really hot summer sun and some winter chilling seem to be the keys to success.
The exquisite dwarf Daphne arbuscula is a much sought after rockery species with small, evergreen, leathery, deep green leaves and fragrant, bright pink flowers. It grows to about 15cm high 25cm wide and is one of the best and easiest to grow of the small daphnes, yet it's hardly ever seen in the nurseries and garden centres. It's a superb plant with all the merits of the rock daphne and few of its faults, being relatively undemanding about soil type and very hardy.
If pollinated, its flowers are followed by small, greyish drupes, which while scarcely a feature, contain a single seed that germinates quite freely if stratified for a few weeks before sowing. Alternatively, sow the seed in autumn in a cool place outdoors, which should provide the necessary chilling. Layers and semi-ripe spring cuttings will root but can take quite a while to strike.
The deciduous species are a group that is quite distinct from the others. When in leaf, the most common species, D. mezereum, could perhaps be mistaken for Daphne burkwoodii, but it's easily distinguished by its habit of flowering on bare wood in late winter and early spring. Both white- and pink-flowered forms are available.
Many connoisseurs regard Daphne genkwa as the most desirable deciduous species. It too blooms before its foliage develops and the flowers are lavender and quite large. Although only slightly fragrant, the flowers are very delicate and pretty. One of this bush's attractions is its young foliage. This, and the new growth, are covered in a fine down, which combined with their coppery colour make them very appealing. Propagation difficulties keep Daphne genkwa a fairly rare plant.
Occasionally you'll come across beautiful species that make you wonder why we don't grow a wider range of daphnes. Daphne longilobata from Tibet and Yunnan is a favourite of mine. It's not a super-fancy plant and its flowers are small, white and only slightly scented, but it appeals to me. Likewise Daphne giraldii, which, while rather more conspicuous in bloom because of its fragrant, bright yellow flowers, relies on subtler charms for its appeal.
Many of the less common daphnes make marvellous garden plants but they're seldom seen in cultivation. Some, such as Daphne blagayana, are well worth trying and avaiable with some effort, but others, like Daphne tangutica and Daphne jasminea, are very hard to find and might reward someone enterprising enough to try and popularise them. Until then we should be grateful for the wonderful plants we already have, which themselves could be much more widely and imaginatively used.
What's in a name?The name Daphne is a classic example of how confusing it would be if we relied on common names to identify plants. Daphne was a nymph of Greek Mythology who changed herself into a laurel to escape rape by Apollo. All rather dramatic, but what has a laurel to do with a daphne you may ask. Well, not much, though Daphne laureola is commonly known as the Spurge Laurel. That's presumably because of its large, evergreen leaves, otherwise Daphne as a genus has little to do with Laurus.
I mentioned that Daphne bholua is one of a group of four Himalayan species that were used to produce paper. Looking at the bush that might seem unlikely, but several other genera of the wider daphne family, the Thymelaeaceae, are also used for paper production. Edgeworthia is probably the best known, and in another example of a confusing common name, it is sometimes known as Paper Mulberry, despite being unrelated to the Mulberry (Morus), which is itself used for paper production.
I am a garden book author and horticultural photographer based in Christchurch, New Zealand. I run a stock photo library called Country, Farm and Garden (http://www.cfgphoto.com). This article may be re-published provided this information is published with it and is clearly visible.