Honeysuckle – Lonicera

The name Lonicera, commemorates Adam Lonitzer, 16^th century German naturalist, the author of a well known herbal book.The genus Lonicera belongs to Caprifoliaceae family. There are known around 180 species growing in the wild on a northern hemisphere.

Szczepan Marczyński

The plants from the genus fall basically into two subgenera. The majority of them are arching shrubs classified in subgenus Lonicera. The other subgenus Caprifolium (Honeysuckle) comprises vigorous vines whose stems twine spirally round a support. I would like to dedicate this article to the latter group.There are around 20 species and several dozens cultivars of honeysuckles in cultivation, of which you can find around 20 taxons cultivated in Poland. Their leaves are arranged in opposite pairs along the stems. In many species, the upper pair of leaves is joined together in a characteristic shape of a saucer. The foliage is most often green or green-blue, but can also be of a different colour e.g. green with yellow veins in Lonicera japonica ‘Aureoreticulata’ or red-purple in autumn and winter in Lonicera japonica ‘Purpurea’. The flowers are the indisputable attraction of honeysuckles – long tubular corollas can be white, yellow, crimson or violet and usually have two lips that curl outwards. What’s more, they are fragrant in many species and cultivars. Lonicera starts blooming in the 2^nd – 4^th year after planting. The flowers are borne in the clusters of three, either in the leaf axils, arranged in pairs, or at the tops of the stems. Depending on the species or the cultivar they appear between the end of May and October. Some Loinceras also bear ornamental fruits – they are multi-seed berries with glossy skin that vary in colour from bright orange through crimson to violet. They ripen from July to October and can attract birds into your garden as they provide food for birds.

Requirements

Honeysucklestolerate the majority of soils with the exception of very poor and drying soil, although they perform best and bloom more profusely in neutral or slightly alkaline, permeable, fertile clayish soil that is rich in hummus and moist but not boggy. They look most impressive when growing in full sun, but as some species and cultivars are more subject to aphids attack in such position, partially shaded spot, sheltered from hot southern sun and strong winds is a universal position for honeysuckles.

Application

Honeysuckles are some of the most valuable garden climbers and can be planted in any garden, but they look particularly imposing in a large, naturalist garden where they are free to grow in an unrestrained manner. They achieve a height of 3 – 6 m, with 0.5 to 2 m of annual growth. They are perfect for climbing up wall constructions, arches, gates, trellises, pergolas, arbours or old tree trunks that are equipped with wires or a wire mesh that will allow them to climb. Grown next to a fence, they will provide an attractive screen against wind, dust and inquisitive eyes of a passerby, replacing well a hedge plant. Evergreen Lonicera acuminata is particularly suitable for this purpose. Some honeysuckles (e.g. Lonicera japonica ‘Halliana’ and ‘Hall’s Prolific’) can be used as a ground cover plant for covering large areas, also in public greenery. Fragrant Loniceras (e.g. Lonicera caprifolium, Lonicera periclymenum, Lonicera x heckrottii, Lonicera japonica and their cultivars) are best planted close to an entrance (a gate or a door), a window or a bank. Honeysuckles are a frequent element in traditional and rustic gardens. They can grow on their own or be combined with other climbers, such as a climbing rose or clematis. It’s best to use vigorous clematis that require hard pruning, e.g. from the Viticella Group or large-flowered late flowering clematis that are cut back just above the ground level in early spring. Otherwise, the pruning will be very difficult to carry out, since the clematis stems will intertwine with Lonicera.

Culture

Most honeysuckles should be light pruned, only when need arises. They look at their best and produce best flowers when left to grow freely. However, if you want your plant really imposing, you should devote the first 1 – 3 years to establishing and forming it. After planting, cut all the stems at the 1/3 of the height to promote strong branching at the base. Then, leave 2 – 4 of the strongest newly grown shoots and remove all the rest. In the next years the honeysuckles that flower on old wood Perfoliate Honeysuckle (Lonicera caprifolium) or Lonicera x tellmanniana) should be pruned very lightly, just to remove weak, dead or obstructing stems. The honeysuckles that bloom on new wood, such as Japanese honeysuckle (Lonicera japonia) and its cultivars or Goldflame Honeysuckle (Lonicera x heckrottii), can be pruned hard in early spring without the fear of losing flower crop. After several years all honeysuckles may start getting bare at the base and producing leaves and flowers only at the upper part of the plant. In order to counteract this, it’s best to carry out rejuvenating pruning every 5 – 6 years. You should spread the task into two years, each year cutting out the half of the oldest stems at the base of the plant. Honeysuckles benefit from abundant watering and fertilization. When you use slow-release fertilizer, for instance Osmocote 5 – 6 M, one fertilization a year is sufficient, best done at the end of April. Use 20 – 30 g per plant (put 2 – 3 teaspoonfuls into 3 – 5 holes, each 5 cm deep).

Diseases and Pests

Aphids are the most troublesome pests of honeysuckles., They appear at the top of the plant in May, just before the flowering. New shoots, leaves and flower buds are the main target of aphids,. Attacked parts curl up, turn yellow, get deformed, stunted and covered with sticky honeydew. Lonicera caprifolium, Lonicera periclymenum, Lonicera x tellmanniana and Lonicera x browniiare particularly vulnerable to aphids attack, especially if they grow in a dry or sunny position. To fight them off, spray the plant with a pesticide immediately after the first aphids have appeared.

Powdery mildew is the most dangerous honeysuckle disease. It causes the appearance of powdery white layer on the upper surface of leaves. With time reddish or brownish stains appear and the leaves curl up, wither and drop off. The susceptibility to the disease varies considerably among species and even cultivars. Perfoliate Honeysuckle (Lonicera caprifolium), is particularly vulnerable, but its cultivar, ‘Inga’ is quite resistant and suffers minor damage. Also most cultivars of Lonicera periclymenum (including ‘Graham Thomas’and ‘Serotina’), Lonicera japonica (with the exception of ‘Aureoreticulata’), Lonicera x heckrottii and Lonicera x browniiare resistant to it. Powdery mildew affects, above all, drying plants that grow in a sheltered, semi-shaded site and therefore don’t have enough air circulation or adequate light. To counter it, spray the plant with one of the recommended fungicides. Repeat spraying 2 – 3 times every 10 days, each time with a different fungicide.

Species and cultvars

• • Lonicera acuminata. Native to northern-east China. Linear, pointed, hairy, dark green, evergreen leaves can freeze during harsh winters. Small, tubular, two-lipped flowers are initially creamy and become yellow with age. Blooms profusely from June to October. Small violet-black berries. A vigorous climber up to 3 – 5m, one of the best evergreen climbers. Well suited for creating screens and covering wire meshes.

• • Lonicera x brownii – Brown’s Honeysuckle. Created about 1850 as a result of a cross between Lonicera hirsuta and Lonicera sempervirens, up to 3 – 4 m tall. Oblong, blue-green leaves are joined at the tips. Slender, tubular, unscented, red flowers with orange throats are borne from June to August. Orange-red fruits in July-August.
    ‘Dropmore Scarlet’. The most valuable of all Brown’s Honeysuckle cultivars, obtained in 1950 in Canada. Orange-red flowers are borne profusely from June to October. Decorative fruits similar to those of the species. Very frost hardy.
    • ‘Fuchsioides’. Slow-growing, compact cultivar up to 1.5 – 2 m tall. Flowers profusely and over a long period from June to October bearing orange-crimson flowers. Particularly recommended for small gardens.
    • ‘Golden Trumpet. A long-flowering cultivar up to 3 m. Copper-yellow flowers from June to October. Orange-red fruits as in the species.

• • Lonicera caprifolium – Perfoliate Honeysuckle. Native to Caucasus and the Middle East. Often confused with Polish Lonicera periclymenum, from which it differs in being more susceptible to powdery mildew and having the upper leaves joined. Very fragrant creamy flowers in May-June, followed by orange fruits in July-October. Ovate to obovate, glabrous, grey-green leaves. The upper pair of leaves (just below the corolla) are joined to form a ‘saucer’. Up to 6 m tall.
    • ‘Inga’ Pink flower buds open to creamy-white flowers. Blooms in May-June, 7 – 14 days longer than the species. Young leaves and shoots are slightly pubescent. Quite tolerant to powdery mildew. A recommendable cultivar, more valuable than the species.

• • Lonicera x heckrotti – Goldflame Honeysuckle. A spontaneous cross between Lonicera americana and Lonicera sempervirens, up to 3 – 6m tall. Introduced in cultivation at the end of 19th century, it’s considered as the most valuable honeysuckle. Lineal, oval or elliptic semi-evergreen or deciduous leaves are dark green on the surface and blue-green underneath. Carmine flower buds open to fragrant, pink flowers, orange-yellow inside. Exceptionally long and free flowering from June to September. The stems are either stiff or slightly twining in habit. It can also be grown as a shrub.
    • ‘American Beauty’. Bright orange, unscented flowers from June to September, followed by crimson-orange fruits in August-October.
    • ‘Goldflame’. A cultivar very similar to the species but the fragrant flowers are of a slightly more intense colour, from June to September.

• • Lonicera henryi – Henry’s Honeysuckle. A cultivar up to 3 m tall, native to China. Lanceolate, glossy, dark green evergreen leaves. Small, tubular, deep purple-violet flowers are not very numerous and appear in June-July. Small, violet-black berries with pale waxy bloom are produced in August-October. It may freeze in harsh winters. Grow in a sheltered, partially shaded or shaded site.

• • Lonicera japonica – Japanese Honeysuckle. Semi-evergreen climber up to 3 – 6m tall, native to Japan, Corea and China. White elliptic to ovate green leaves. Tubular, 2-lipped, intensely fragrant flowers, that are initially creamy-white and become yellow at the end of the flowering period, are borne through all summer. Blue-black berries. Its cultivars are more valuable than the species and are more recommended.
    • ‘Aureoreticulata’ – Interesting, green leaves with yellow veins, the variegation is most prominent in full sun. Small, slightly fragrant flowers initially white become yellow with age. It may be used either as a climber or as a ground cover plant. Susceptible to powdery mildew. It may freeze in harsh winters.
    • ‘Halliana’ – A vigorous semi-evergreen climber that turns in summer into a billowing cloud of small, fragrant flowers that are creamy-white on opening and turn yellow with age. It attains a height of 5m, but may also be used as a ground cover plant in large areas. Suitable for covering fences and creating various kinds of screens. Well suited for public greenery.
    • ‘Hall’s Prolific’ – A cultivar selected in Holland from ‘Halliana’, but its flowering period starts earlier, lasts longer and more profuse. It has similar applications and growth habit to ‘Halliana’ but it’s less frost hardy.
    • ‘Purpurea’ – Evergreen or semi-evergreen leaves, green with purple veins in summer and deep purple in autumn and winter. Small, tubular, fragrant flowers, violet outside. The inside of the corolla is initially white and turn yellow with age. Grows up to 4m tall (1-2m of annual growth).

• • Lonicera periclymenum – Woodbine Honeysuckle. A popular vigorous climber up to 7 m tall, native to Central and Western Europe as well as Northern Africa. Ovate to oval leaves, green on the surface, blue-green underneath. They are paired at leaf axils but not joined (what distinguishes it from Lonicera caprifolium). Intensely fragrant, creamy flowers sometimes streaked red, borne from May to July. Decorative, deep red, glossy fruits from July through autumn. It’s more valuable and more disease resistant than Lonicera caprifolium. Its cultivars are particularly recommendable:
    • ‘ Belgica Select’ – An early-flowering, Dutch cultivar up to 3 m tall (1 m of annual growth). Purple-veined leaves. Young shoots and flower stalks are purple-violet. Pale, violet-black flowers, the inside of the corolla is initially creamy and become yellow at the end of the flowering. It blooms intermittently from May to October. Decorative red fruits in September-October.
    • ‘ Chojnów’ PBR – A new Polish cultivar introduced in 2006, up to 2 – 3 m tall (1 m of annual growth). Intensely fragrant, deep purple flowers on the outside, creamy on the inside. They are borne in great profusion and cover the plant from top to bottom in June – September. Red fruits from August to October. Leaves are purple-green when young, turn green with age.
    • ‘Graham Thomas’ – A very valuable cultivar, named after an English naturalist. It blooms very profusely and over a long period, from May to September. Relatively large, intensely fragrant, tubular flowers, creamy at the beginning and yellow at the end of the flowering, are followed by ornamental, red, glossy fruits (June to October). It grows up to 4 m (1 – 2 m annually).
    • ‘Serotina’ – The most frequently cultivated honeysuckle. A vigorous Dutch cultivar up to 3-6m tall. It’s quite late-flowering (2 – 3 weeks later than ‘Belgica Select’). Intensely fragrant flowers, violet-red outside, creamy inside, are borne from June to September. Attractive, coral, glossy fruits from July to October.

• • Lonicera sempervirens – Trumpet Honeysuckle. North American species. Semi-evergreen or deciduous leaves. Tubular flowers, red outside, yellow inside. It may freeze in harsh climates, and in such case it’s better to use its more hardy cultivars.
    • ‘Blanche Sandman’. A valuable American cultivar that is hardier than the species. Crimson outside, yellow inside flowers are borne in profusion and over a long period, from June to October. Orange fruits in July-October.

• Lonicera x tellmanniana – Tellmann Honeysuckle. A Hungarian cross between Lonicera sempervirens and Lonicera tragophylla. Oval to elliptic-ovate leaves are dark green on the surface and blue-green-white underneath. The upper pair of leaves is joined forming a sort of a saucer. Very ornamental, large, tubular, 2-lipped copper-yellow flowers are unfortunately unscented. Borne from June-July, they are followed by orange fruits in July-September. Plant in semi-shade for best performance and flowers.