Blue honeysuckle

Family

Caprifoliaceae

Habit

Shrub

Height

1.8 m

Spread

2.5 m

Growth

very fast

Lifespan

30 years

First yield

after 3 years

Hardiness

zone 3–9

Shade tolerance

light shade

Soil

Sand, Silt, Loam

Soil moisture

moist – very wet

pH

5 – 7.5

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Edible: The cylindrical to pear-shaped berries, black-blue with a pale blue bloom, ripen from late May to mid-June and are therefore the first soft fruit of the year, which gives the plant its German names Maibeere and Lenzbeere. Fresh they taste pleasantly sweet-sharp and recall bilberries. The wild form bears small fruit of about half a gram, Russian selections run 0.5 to 0.8 grams, Canadian ones 1.4 to 1.6 grams, and dedicated fruiting cultivars reach up to four centimetres in length. Two to six kilograms per bush are possible. Analyses give 6 to 8 per cent sugar and 2 to 4 per cent fruit acids against 45 to 120, exceptionally up to 170 milligrams of vitamin C per 100 grams, plus anthocyanins, rutin and further flavonoids. The fruit is made into juice, compote, purée and jam, often blended with other fruit; in Russia it is preserved in sugar syrup as varenye.

Medicinal: There is no documented medicinal use in the Central European sense; here the species is fruit, not a medicinal plant. What is recorded comes from the Russian Far East and Kamchatka, where infusions of the berries were traditionally drunk for colds, fever and stomach complaints — historically attested, without evidence of efficacy. The constituents that might underlie this are well documented: anthocyanins, rutin, further flavonoids, proanthocyanidins and phenolic acids, credited with antioxidant and anti-inflammatory properties, together with 45 to 120 milligrams of vitamin C per 100 grams. No healing effect follows from these laboratory findings.

Other uses: Beyond the fruit the uses are modest but not negligible. The densely branched habit, only one to two metres high, makes the species a workable hedging shrub for small gardens; in parts of northern Europe it is also used as a hedge and group plant in public planting. Because it tolerates root and shade pressure it can be planted beneath larger trees, where most soft fruit gives up, and it does well in containers and on terraces. Its real added value lies in the flowering date: the yellowish bell-shaped flowers open as early as April and are among the first nectar sources of the garden year. As an ornamental it is valued for this early bloom and for the unusually shaped blue fruit.

Not a full-sun shrub: it takes drought and draughts extremely badly. It needs evenly moist, mulched soil, shelter from wind and preferably the company of other woody plants to give it partial shade. Practice confirms this repeatedly — in a fully sunny, dry, unmulched position one plant stayed short and bushy under drought stress and bore only a few small berries, and in an agroforestry system every planted specimen of the Siberian variety died in its first year. Partly shaded, sheltered positions with a good, even water supply are therefore the recommendation from growers. Most cultivars are self-incompatible and need a second, genetically different shrub with overlapping flowering within range.

The wild species can be raised from seed, but seedlings are variable and take some years to bear. In any case cultivar choice matters more than propagation method: the flowers are self-sterile, so at least two different cultivars flowering at the same time must stand together, otherwise no fruit sets. Named selections are therefore passed on vegetatively only. Layering is the simplest route: a low shoot is pegged down in spring, mounded with soil and severed the following year. Suckers and softwood cuttings taken from still-soft new growth in early summer and rooted under film are equally common. Because the bushes grow slowly and upright, a planting distance of 1.25 to 1.50 metres is sufficient.

The European variety has high ecological value for native fauna: it flowers very early in the year and so supplies pollen to specialist insects as well, at a time when scarcely anything else is in bloom. It is also considered better adapted to Central European conditions than the Far Eastern cultivars.

Naming in the trade is consistently sloppy, which matters when buying: the Siberian strain is Lonicera caerulea var. kamtschatica and lies behind most cultivars marketed as honeyberry or haskap; the European strain is Lonicera caerulea var. caerulea. A label such as Lonicera caerulea 'Maistar' is therefore wrong or at least incomplete — that cultivar belongs to the Siberian variety. Of the European variety only two fruit selections from wild populations are so far in the trade, whereas considerably more breeding work has gone into the Far Eastern cultivars.

Circumpolar in the northern hemisphere: northern and eastern Europe, Siberia, East Asia and north-western North America. The species splits into several subspecies with clearly separated ranges: subsp. caerulea occupies Europe and the East Asian region, subsp. altaica the Altai together with Siberia, Kazakhstan and Mongolia, subsp. pallasii Scandinavia, the Baltic states and Russia, subsp. stenantha Afghanistan, Central Asia and the western Himalaya, and var. cauriana north-western North America. In Central Europe the natural occurrence is confined to the mountains; in Germany it grows wild only in Baden-Württemberg and Bavaria, with subsp. borbasiana in the north-western Balkans. The large-fruited garden forms sold as honeyberry or haskap derive from the East Asian Kamchatka strain and were bred mainly in Russia and Canada.

Blue honeysuckle is a shrub of cool, moist, acidic ground. It grows in damp mountain forests, above all in spruce woodland, in the scrub of the krummholz zone and along the margins of raised bogs, as well as in blackthorn hedges and grey willow thickets. Soils are moist to wet, poor in nutrients and lime, and often carry a raw humus layer; the species avoids lime. Its centre of distribution lies in the montane to subalpine belt and reaches about 2100 metres. This origin explains its behaviour in the garden: it tolerates short growing seasons, hard frost and the root and shade pressure of larger trees, but reacts badly to drought and to calcareous soil.