Japanese Honeysuckle, Lonicera japonica.

Beautiful Flowers with a Scent of Vanilla

Our Japanese Honeysuckle, Lonicera japonica, is flowering profusely at the moment. It started flowering in June and will continue to do so until we have our first severe frost. It’s a cheery sight. The flowers smell of vanilla (especially on a warm evening) and in the warmth of early October it attracted early autumn visitors to the garden, such as queen Buff-tailed Bumblebees (Bombus terrestris) and a fleeting Hummingbird Hawkmoth (Macroglossum stellatarum).

When we moved here, just over ten years ago, the Japanese Honeysuckle was the only plant of any significant size in the garden, which was otherwise covered in lawn, slabs and gravel. It hides – and keeps together – a wooden trellis that divides the garden in two.

We are very lucky to have House Sparrows (Passer domesticus) in our garden. They love the dense tangle of our Japanese Honeysuckle and spend a lot of time there, darting out to the bird feeders and nesting in nearby eaves.

Lonicera japonica is a member of the family Caprifoliaceae (note 1). It’s a climbing shrub which is partially winter-green, only losing its leaves in colder winters. It is widely grown in gardens, usually as Lonicera japonica var. halliana, known as ‘Haliana’ in the UK and ‘Hall’s Prolific’ in the United States.

Native to Eastern Asia

Lonicera japonica is a native of eastern Asia, including Japan, Korea, Taiwan and many parts of China. It has been introduced to many other parts of the world, including the British Isles and other parts of Europe, other parts of Asia, North and South America, parts of Africa, Tasmania and North Island in New Zealand. It is easy to understand why: it makes a useful and lovely screen.

Japanese Honeysuckle is also known as Gold-and-silver Honeysuckle because of its flowers, which start off white and age to a golden yellow. The flowers are followed by berries, which ripen to black.

Japanese Honeysuckle, Lonicera japonica. The flowers start off white and age to a golden yellow.

Widely Introduced

Lonicera japonica was introduced into Britain in 1806. It can now be found growing in the wild in the British Isles, in woodland margins, scrub, hedgerows and on waste ground. Most records are from England and Wales, with some more in the south of Ireland, with outliers in Western Scotland and Northern Ireland.

Japanese Honeysuckle can spread very successfully. Birds and other animals eat the berries and can disperse the seeds in their droppings. The plant spreads vegetatively too and I have noticed in our own garden how the long twining stems travel across the ground and root where they meet the soil. Sometimes humans provide assistance – some of the wild Japanese Honeysuckle plants are garden throw outs.

Colonies of Japanese Honeysuckle can be long lived, such as at Bere Ferrers in South Devon where the plant has been known since 1937. In North Norfolk, a large colony of the Japanese Honeysuckle has become established on the coastal defence bank at Cley-next-the-Sea. The BSBI Plant Atlas notes that the plant’s range appears to be increasing here.

Sometimes Invasive

Elsewhere, Japanese Honeysuckle can be far too successful. In New Zealand it is listed in the National Pest Plant Accord as an unwanted organism and in North America it is classified as a noxious weed in Texas, Illinois, and Virginia and is banned in Indiana and New Hampshire. The plant spreads most successfully into forests when the canopy has been opened up, such as by felling.

Ireland’s National Biodiversity Data Centre website cites several studies on the detrimental effects of Lonicera japonica in the United States, including a decline in native species in areas it has colonised. The plant is thought to inhibit the growth of competitors by means of allelochemicals (chemicals that prevent the growth of other plants) and thrives because it lacks specialist herbivores.

Where they are growing in the wrong place, small patches of Japanese Honeysuckle can be removed by hand or dug out, but all plant parts including roots and rhizomes must be removed to prevent resprouting. Larger patches are removed through repeated mowing or by the use of herbicides. There is currently no known biological control. The Invasive Plant Atlas of the United States and University of Florida Center For Aquatic and Invasive Plants websites provide useful information; the latter has more details on control of Lonicera japonica in the United States. It also lists some American natives that can be grown instead (note 2).

Uses For Food and Medicine

The Plants For A Future website notes that the flowers and leaves of Lonicera japonica are edible but the leaves contain saponins and must be cooked thoroughly first. I haven’t bothered to eat either of them, though we once made an acceptable wine from the flowers of Lonicera periclymenum (Common Honeysuckle) growing in our previous garden. Wikipedia gives details of Japanese Honeysuckle’s uses in Chinese medicine.

Worth Growing in the British Isles

In the British Isles I wouldn’t hesitate to grow Japanese Honeysuckle in my garden. The RHS website gives details of Lonicera japonica ‘Halliana’ and how to grow it. Our plant thrives on well drained soil in a sunny spot. Lonicera japonica is hardy to -10 to -15C (UK hardiness rating H5).

In our garden it grows to about 2.5 metres (8 feet) tall and spreads about double that distance along the trellis. I prune the top shoots once or twice in the summer and remove wayward, rooting branches – though if you want a free plant to give away these can be dug up and planted elsewhere. If you want to buy a Lonicera japonica, a Google search gives plenty of online stockists and your local garden centre probably has it too.

Notes

Note 1 – I wrote about its relative, the shrubby, winter-flowering Lonicera × purpusii ‘Winter Beauty’, in March 2015. It is one of the species and hybrids of Lonicera listed in Clive Stace’s “New Flora of the British Isles“ (Fourth Edition, 2019). Just one of these, Lonicera periclymenum (Common Honeysuckle), is a British native. It also occurs in many garden varieties. See Mike Crewe’s Flora of East Anglia for comparative photographs of the species of Lonicera that occur in our part of the British Isles.

Note 2 – Ironically one of these is Virginia creeper (Parthenocissus quinquefolia), which can be a real thug in our garden, where it spreads from behind our fence into the shrubs at the end of our garden.