- Type
- Trees & Vines
- Difficulty
- Easy
- Season
- Spring·Summer
- Sowing
- Plant a sapling
Japanese Honeysuckle
Lonicera japonica
Chlorogenic acid and luteolin · a flowering vine that climbs a fence
Japanese honeysuckle is a semi-evergreen climbing shrub trained over fences and trellises. From May to July, paired tubular flowers open at each leaf axil, white at first and turning yellow within a few days. Because white and yellow flowers hang on the same plant at once, it took the name geumeunhwa, gold-and-silver flower. The Donguibogam lists it in the Herb section under the hanja name Indong and records the Korean name as gyeoasari neochul, adding that it is called indong because it does not wither through winter, and jwajeondeung because the vine twines to the left. Buds picked just as they are about to open and dried in the shade become a flower tea. Analyses report phenolic acids such as chlorogenic acid and luteolin-type flavonoids in the dried flowers. Once rooted it asks for almost nothing, but that same vigour lets it wind around neighbouring shrubs and constrict them, so the runners have to be cut back each year to hold its ground. The dark red berries that follow in autumn are not eaten.
Year-Round Calendar
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Where It Grows
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Main producer
Supplies most of the flower buds traded as jinyinhua. Pingyi in Shandong and Fengqiu in Henan are the best-known growing areas. Harvest May, June
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Major producer
Grows wild on hillsides and along hedges throughout the country, with some planted and raised in fields. Harvest May, June, July
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- Wild population Called suikazura, it grows wild across Honshu and southward. It is not raised as a field crop.
Its native range is East Asia, across Korea, China, Japan and Taiwan. China is overwhelmingly the largest harvester and seller of the flower buds, and the Chinese market draws a line between buds from Japanese honeysuckle (Lonicera japonica), sold as jinyinhua (gold-and-silver flower), and buds from other species (L. macranthoides and the like), sold as shanyinhua (mountain silver flower) — so the tonnage should not be read as coming from a single species. In southeastern North America, New Zealand and Australia the plant was introduced by people, spread into the woods, and is treated as an invasive species, so those places are not listed here as growing areas.
- Optimum
- 15~28℃
- Range
- 0~35℃
- Hardiness
- Hardy
A woody vine that tolerates cold, shade and poor soil alike. In the south it carries its leaves right through the winter; in the central region about half of them drop. The sunnier the spot, the more heavily it flowers.
Harvested 2–3 years after planting. In the year it is planted there are few flowers; after two or three years, once the vine has settled in, it blooms enough to pick every year. Once established, it keeps spreading by root and stem.
In Korea Nationwide
Common nationwide on hillsides, embankments and hedges. The flowers are picked as buds from May to July, and the stems and leaves are gathered once the flowering is over.
How to grow
- Light
- Full sun gives the most flowers. It survives in part shade but sets fewer
- Soil and depth
- Undemanding. It grows in poor ground as long as drainage is good. At least 30cm deep
- Spacing
- One and a half metres or more between plants. Put the trellis or fence up first, then plant beneath it
- Watering
- Keep it from drying out through the first year only. Once rooted it carries itself on rainfall
- Feeding
- Work a spadeful of compost around the base in November or December after leaf fall. Heavy nitrogen builds leaf at the expense of flowers
- Harvest
- May to July. Pick the buds just as they are about to open and spread them to dry in the shade. Once fully open the scent fades and the colour dulls as they dry. Stems and leaves are gathered and dried after flowering
What makes the difference. Cut the flowered shoot back to about two nodes and side shoots follow, adding flowering points for the next year
Why this one is harder. Roots and stems run together, and within a few years the planting spreads past where it started and winds around neighbouring shrubs. In a small plot, start it in a large pot or cut back the runners each winter to hold the boundary
Common problems
- Aphids You will see Colonies on shoot tips and around the buds, turning sticky What to do Wash off with a jet of water; if it recurs, use an egg-yolk oil spray. On a plant whose flowers will be picked, observe pre-harvest intervals
- Powdery mildew You will see Floury white patches on the upper leaf surface after the rainy season What to do Thin the tangled growth to open an air path. Remove affected leaves and take them away rather than dropping them on the soil
- Scale insects You will see Brown shell-like bumps on older stems, with leaves turning sticky What to do Scrub them off with a brush in winter and thin the old stems. If it spreads, cut that stem out at the base
This page describes how a crop is grown and used. It does not claim health effects for any food, nor is it intended to prevent or treat disease. Component and study notes are references only and do not mean the same result occurs in people. Consult a medical professional about health concerns.
Health Benefits
The old record — indong (忍冬). The Donguibogam lists the plant in the Herb section under the hanja name Indong and records the Korean name as gyeoasari neochul. Its nature is set down as slightly cold, its taste as sweet, and it is described as having no toxicity. The text notes that it grows everywhere, that the stems are red-purple, that older stems carry a thin white membrane while young ones are downy, and that the flowers are white with purple stamens. It records gathering in the twelfth lunar month and drying in the shade. It also gives the origins of the names: indongcho because it endures winter without withering, jwajeondeung because the vine twines to the left, and geumeunhwa because the flowers come in two colours, yellow and white. What an old medical text wrote differs from how it is judged today.
The colour change behind the name. White and yellow flowers on one plant are not two kinds blooming together; each flower opens white and turns yellow within a few days. The name geumeunhwa simply records that change, and the line 花有黃白二色 in the old text points at the same scene.
Analyses of the flower. Chlorogenic acid and related phenolic acids, luteolin-type flavonoids and iridoid glycosides have all been isolated from honeysuckle flowers in repeated analyses. The same work reports that levels vary with picking time and drying method. These are compositional analyses and nothing beyond that.
Nutrition
- Chlorogenic acid (found in the flower buds) — a phenolic acid reported across the genus Lonicera
- Luteolin-type flavonoids (found in flowers and leaves) — a group of yellow-toned flavonoids
- Iridoid glycosides (found in flowers and stems) — bitter compounds such as loganin and secologanin
The bud, not the open flower What goes into the tea is the bud just before it opens, not the flower in full bloom. Picked whole and dried in the shade it keeps its scent; dried in direct sun the colour goes dull and yellow. Seal it once fully dry and keep it somewhere cool, since damp takes the aroma first.
Phenolic acids such as chlorogenic acid Analyses repeatedly report chlorogenic acid and related phenolic acids in honeysuckle flowers. It is the same family of compounds found in green coffee beans and apples. This entry stays with the compositional record.
Luteolin-type flavonoids Luteolin and its glycosides have been isolated from the flowers and leaves. What such compounds do in a laboratory assay is not the same as what happens in the body over a cup of tea. How much actually dissolves into the water depends on brewing temperature and time.
Iridoid glycosides and bitterness Iridoid glycosides such as loganin and secologanin are reported across the genus Lonicera. That is why a long steep turns bitter before anything else. Water taken off the boil for a moment and a steep of about three minutes keeps the floral note in front.
Pairings
○ A short steep — Use a pinch of dried buds and water taken just off the boil, and steep for about three minutes. Left longer, bitterness arrives first. A second pour still carries scent.
○ Blended with chrysanthemum or mint — A little dried chrysanthemum or mint tidies the flat finish of honeysuckle. Roughly three parts honeysuckle to one part of the rest works. Each ingredient releases at its own pace, so add them together and keep the steep short. Gamguk (Indian Chrysanthemum)
○ Flowers in honey — Rinse fresh flowers lightly, dry them completely, then pack them in honey. Any water left behind invites mould. Stirred into cold water it becomes a summer drink.
△ The berries are not eaten — Japanese honeysuckle sets dark red berries in autumn, and they are not eaten. Along a fence children pass, strip the berries within reach in advance. Keep the harvest to flowers and leaves only.
△ Roadside plants and nursery stock — Honeysuckle on a roadside fence has usually met exhaust and herbicide. Ornamental nursery plants are often treated with pesticide before sale, so their first season of flowers should not go into tea. Plant your own well back from traffic and pick from the second year.
△ It constricts neighbouring shrubs — The vine twines to the left and can bite into the stems of young trees. Keep it away from fruit trees and shrubs and give it a trellis or fence of its own. Cut back the runners each winter to return it to its allotted space.
Varieties
- Native Japanese honeysuckle (sapling) — The standard line, opening white and turning yellow. The buds are dried as geumeunhwa
- Red honeysuckle types (sapling) — Ornamental lines with long-lasting red tubular flowers, planted for the look of a fence
Source: Donguibogam, Herb Section 忍冬 · Rural Development Administration (Nongsaro) · Korea National Arboretum