Daphnes — The Hopeful Fragrance of Spring
It might not seem like the best advice to plant a shrub that was described by the horticulturalist, Michael Dirr, as sometimes dying suddenly “for no explicable reason.” But that warning can be a tempting gauntlet to throw down before an intrepid gardener. Dirr also said that even a single-flowering season of a daphne would justify its use.
The genus name of daphne was originally used for laurel (Laurus nobles). It was later transferred to this genus which has between 70-95 species of deciduous and evergreen shrubs in the family Thymelaeaceae, native to Asia, Europe and North Africa. (A species is a variant that evolves naturally from related forebears, surviving and eventually stablilizing because it is better adapted to its environs. A cultivar is a variant produced by humans, by crossing natural species and favoring those with some desired trait.) There are daphnes suitable to southern climates, northern climates, partial shade, sunny rock gardens, and even containers.
While the Daphne odoras are restricted to more southern climates up to zone 7, the D. mezereum, D. alpina, and D. cneorum species, and the Burkwoodii cultivars, can withstand winters up to zones 4-5. There are general characteristics, however, that typify this genus regardless of planting zone. These shrubs are known for being slow to establish and downright perverse about being moved once settled. Their winter hardiness can be bolstered by selecting sites in more protected areas out of the path of biting wind. Daphnes generally require well-drained, sandy-humusy soil with a neutral pH of 6.5 to 7. Some gardeners add sand or gravel to assure good drainage. Poor drainage is a major cause of plant failure in the landscape. In areas of heavy clay soils, raised beds can be beneficial. Established plants have some drought tolerance, but soils should not be allowed to dry out. Summer mulching helps keep the roots cool. All parts of the plant, including leaves and berries, are poisonous, so it is truly deer resistant. Pruning requirements vary by cultivar. Potential diseases include botrytis, leaf spots, canker, twig blight, crown rot, root rot and virus. Potential insect pests include aphids, mealybugs and scale.
Daphne Species and Cultivars
The strongly aromatic blooms of the species Daphne odora appear in the sometimes bleak, gray weeks of late February to mid-March, just when the increasingly impatient gardener needs an encouraging sign of spring.
D. odora or winter daphne is hardy only to about 10 degrees F and is suited to planting zones 7-9. Its winter hardiness can be bolstered by placing the shrub in a more protected area out of the path of biting winds; plants weakened by winter injury are more susceptible to disease. In hot climates, plants benefit from afternoon shade because their foliage is vulnerable to sun scorch. Summer mulching is recommended to help keep the roots cool. This smaller-sized shrub, about 3’ to 4’ tall and 2’ to 3’ wide, does not usually require any pruning which is fortunate because its mature wood does not heal well from cuts. You can cut the flowers, however, without injuring the plant, and the blossoms keep well in water. The deeply scented flowers are reddish-purple with insides of pale pink to white in terminal inflorescences. Flowers are followed by red fruits in July-August, but fruits are infrequently produced on cultivated shrubs.
The most common D. odora cultivar, ‘Aureomarginata,’ has leaves with narrow, irregular yellow margins and terminal clusters of small flowers that are white inside, and deep, purplish pink outside. ‘Aureomarginata’ is also noted for having slightly better winter hardiness than other D. odoras and can grow to a height of 5 feet.
Daphne x burkwoodii ‘Somerset,’ a cross between D. cneorum and D. caucasica, is suited to zones 5-8. This cultivar is a slow-growing, densely branched, deciduous shrub which typically grows 2’ to 3′ tall and 4’ to 5’ wide with a rounded, mounding habit. It features clusters of extremely fragrant, creamy white to pale blush-pink flowers in late spring which are followed by tiny red drupes in fall. Small, dense, oblong, bright green leaves often persist well into December with no fall color.
Daphne x burkwoodii ‘Carol Mackie’, a cross between D. cneorum and D. caucasica, will survive in zones 4-8. ‘Carol Mackie’ is most noted for its striking cream-edged variegated foliage that lasts well into December. This cultivar is a dense, slow-growing, deciduous shrub which typically grows 2’ to 3′ tall and 3’ to 4’ wide with a rounded, mounding habit. Fragrant clusters of pale pink flowers bloom in late spring followed by tiny red drupes. Once established, about ¼ of old growth should be pruned yearly to about 6” in height. ‘Carol Mackie’ prefers a neutral to slightly acidic soil pH.
D. mezereum, commonly called February Daphne because of its late winter flowers, is one of the hardiest of the daphne species. It grows in zones 4-7. This small deciduous shrub typically grows to 3’ to 5′ tall and as wide. A native of Europe and Western Asia, it was introduced into America in colonial times. It dislikes the hot, humid summers of the south and thrives in shaded, woodland areas of cooler-weather states. Although it prefers partial shade, it can tolerate full sun if the soil is kept uniformly moist. Oblanceolate (rounded apex and tapered base), dark green leaves are arranged spirally along the stems. Fragrant reddish-purple to pink flowers bloom in late March to early April prior to the emergence of the leaves. Flowers are followed by small fruits which mature in June.
All parts of this plant are poisonous to humans if ingested; plant saps also typically cause skin irritations. Plant saps were once used in a rouge-like cosmetic until it was discovered that rosy cheeks were the result of blood vessel damage rather than the blush of good health. Birds can eat the berries without ill effects.
D. mezereum f. ‘Alba’ is an upright deciduous shrub with narrow, dull green leaves and very fragrant white flowers that blooms in late winter and early spring, prior to the emergence of leaves; the flowers are followed by yellow berries. The shrub prefers moderately fertile, well-drained (but not dry) soil, in sun or part shade. Aphids may be a problem; ‘Alba’ is also subject to gray mold (Botrytis) and a virus.
D. mezereum ‘Alpina’ is a slow-growing, semi-prostrate form that eventually forms a gnarled compact shrub. White flowers, similar to the species, are produced in the spring. This mezereum cultivar is different from Daphne alpina.
D. alpina is a deciduous prostrate species of daphne which can tolerate cold climates up to zone 5. The mid-green, simple oblanceolate leaves are alternate. The shrub produces panicles of white salverform flowers (trumpet-shaped flowers that start as a narrow tube and widen into a flared mouth) from May to June. The flowers give way to orange drupes. D. alpina prefers a sunny to half-shady situation in moderately moist soil of gritty loam.
D. cneorum, Rose Daphne, Garland Flower or Rock Daphne, is a prostrate species which grows from 6” to 12” tall with a spread to 3’ or more. It tolerates climates as cold as zone 4. It is a slow-growing groundcover with alternative, very narrow, oblanceolate leaves. Its bright pink, fragrant flowers cover the shrub with a massive display in April and May and exude a sweet, intense fragrance. Prune after flowering; it may rebloom if sheared after first bloom. It prefers well-drained, moist, pH neutral soil in full sun to partial shade. It can be subject to leaf spot, crown rotting and cankers. It gets its name ‘Rock Daphne’ because it is often grown in rockeries. This plant also does well and is very attractive in raised beds, border plantings, rock gardens, and containers.
D. cneorum ‘Eximia’ is an evergreen, prostrate shrub, growing to about 8’ in height, with terminal clusters of fragrant, bright pink flowers opening from red buds, occasionally followed by brownish-yellow berries. The shrub can be grown in areas up to zone 5 in full sun to part-shade but is not reliably hardy in exposed conditions. This vigorous cultivar has gained the Royal Horticultural Society’s Award of Garden Merit.
Many of the daphnes are small, rounded shrubs which makes them quite effective as anchor plants in smaller gardens. The beautiful, highly fragrant blooms and variegated evergreen foliage of D.odora justifies its use as an eye-catching accent plant. Daphnes can also be massed in shrub borders as long as they are situated in protective sites. Good drainage is a necessity and so the plants are good candidates for raised beds. The smaller shrubs do well in containers and the prostrate forms are well-suited to rock gardens or used as fillers in foundation plantings. Daphnes should certainly be stationed in a spot where you can enjoy their fragrance. They offer a welcoming presence along an entry path, by the sides of porch, in a corner of a deck or patio, or any other gathering place or high-traffic area. Spend some time evaluating the proper site so that you don’t need to move them once they’re established. And then, breathe in deeply and enjoy!