The Sweetberry Honeysuckle (Lonicera caerulea), also known as Honeyberry or Haskap, is a shrubby and fruit-bearing plant of great importance both for horticulture and human consumption. Its cultivation has been gaining prominence in temperate climate regions due to its resistance to extreme cold and early fruit production rich in bioactive compounds. Moreover, the Lonicera caerulea is valued for its adaptability to different soil types and as a viable alternative to the cultivation of other fruits in areas with less acidic soils, where traditional blueberry faces growth challenges.
From the same genus as the Japanese Honeysuckle (Lonicera japonica), the Lonicera caerulea is a circumpolar species, native to the cold temperate regions of the Northern Hemisphere, covering areas of Asia, Europe, and North America. Its natural habitat includes humid boreal forests, forest clearings, and marshy areas with soils rich in organic matter, often found in regions of heavy peat bogs.
In Europe, the Lonicera caerulea was initially valued as an ornamental plant due to its discreet flowers and decorative fruits. Only in recent decades, with the advancement of genetic improvement programs, has its potential as a fruit plant begun to be commercially exploited. In North America, interest in the species grew from the 2000s, driven by research conducted in Canada and the United States, which demonstrated its potential as an alternative to blueberry in regions with less acidic soils.
The Sweetberry Honeysuckle also stands out for its resistance to pests and diseases, making it a viable option for organic cultivation and agroforestry systems. Its ability to bear fruit early, even in cold climates, and the nutritional richness of its fruits, rich in anthocyanins and vitamin C, confer it the status of “superfruit” in specialized markets.
The botanical name Lonicera caerulea originates from the genus Lonicera, named after the German botanist Adam Lonicer (1528–1586), known for his contributions to botany and herbal medicine. The specific epithet “caerulea” derives from Latin and means “blue,” referring to the characteristic color of the fruits of this species. Additionally, the common name “haskap” is used in Japan to designate the variety Lonicera caerulea var. Empyllocalyx originates from the Ainu language, spoken by the indigenous people of Hokkaido, where “haskap” means “fruit of longevity” or “blue fruit”.
The Lonicera caerulea, belonging to the Caprifoliaceae family, is a deciduous shrub species, perennial and woody, typically ranging between 4 and 6.5 feet (1.2 to 2 meters) in height, and can reach up to 8.2 feet (2.5 meters) in selected cultivars. Its root system is shallow but well-branched, with fine, fibrous roots that develop laterally, adapted to moist, well-drained soils. The plant features a main erect stem, lignified, with a grayish-brown color and a rough texture as it ages. Young branches are green, flexible, and have a semi-woody texture, gradually becoming woody and brittle over time.
The growth habit is erect to slightly arched, with a tendency to form multiple stems from the base, creating a dense shrubby appearance. Branching is sympodial, with short internodes in cultivated varieties and longer in wild forms. Side branches experience vigorous growth in the spring and serve as the main supports for leaves, flowers, and fruits.
The leaves are opposite, simple, with short petioles and leaf blades elliptical to ovate in shape, measuring between 1.2 and 3.1 inches (3 to 8 cm) in length. Their margin is entire, the apex is acute or slightly rounded, and the base is attenuated. The texture is papery to sub-leathery, with a smooth or slightly pubescent surface, mainly on the underside. The color is dark green on the upper side and bluish-green on the lower, with clearly visible veins. Leaf fall occurs in the autumn in response to decreased temperatures and daylight, with regrowth resuming at the end of winter or early spring.
The inflorescence of Lonicera caerulea is a dicasy, generally axillary or terminal, composed of pairs of flowers directly inserted at the nodes of new branches. The species is considered functionally monoecious and self-fertile, although cross-pollination significantly enhances the yield and quality of the fruits. Flowering occurs early, typically between late winter and early spring (February to April in the Northern Hemisphere), before the full development of the foliage.
The flowers are small, tubular, and bilabiate, with zygomorphic symmetry, measuring 0.4 to 0.8 inches (1 to 2 cm) in length. They exhibit colors ranging from white to pale yellow, gradually turning slightly cream as they age. Each flower has five fused petals forming a tube with two unequal lips, five stamens, and a bicarpellate inferior ovary.
Pollination is entomophilous, primarily conducted by bees, particularly the genera Bombus and Apis. The attractiveness of the flowers to pollinators is linked to the release of nectar and the exposed arrangement of the anthers. In cold regions, efficient pollination depends on the presence of pollinators active at low temperatures, a trait of species adapted to boreal climates.
The fruit is an elongated ellipsoid berry, intensely blue in color with a surface coated by a waxy bloom, giving it a slightly opaque appearance. It measures between 0.4 and 1.6 inches (1 to 4 cm) in length and ripens early, typically from late spring to early summer. The pulp is juicy, with a sweet and tart flavor reminiscent of a combination of blueberry and raspberry, and contains high levels of anthocyanins, phenolic compounds, and vitamin C. Each fruit has two to three small, light brown seeds embedded in the pulp, with low viability for direct propagation.
The fruits are traditionally consumed fresh right after harvest but are also widely used in the preparation of juices, jams, preserves, wines, liqueurs, and desserts. Due to their intense color and antioxidant properties, the fruits are also used in the production of functional products like smoothies, energy bars, and powdered supplements. When dehydrated, they retain a good portion of their bioactive compounds and can be utilized as healthy snacks or as ingredients in baking. Furthermore, the fruit extract is increasingly exploited in the nutraceutical and cosmetic industry, expanding their application beyond conventional food uses.
Sweetberry Honeysuckles exhibit a remarkable diversity of varieties and commercial cultivars, a result of centuries of natural selection and, more recently, breeding programs conducted in countries such as Russia, Japan, Canada, and Poland. This diversity aims to enhance characteristics such as flavor, fruit size, cold resistance, and adaptation to different climate and soil conditions.
In Europe, for example, the variety Lonicera caerulea var. caerulea occurs in moist forests and high-altitude swamps, from the Pyrenees to the Alps and parts of Central Europe, such as Austria and Germany. In North America, the variety Lonicera caerulea var. villosa is found in the moist areas of eastern Canada and the northeastern United States. In Asia, the variety Lonicera caerulea var. kamtschatica is common in the Russian Far East, including the Kamchatka Peninsula and the Kuril Islands, while the variety Lonicera caerulea var. edulis occurs in regions of Siberia, Japan, and China.
Sweetberry Honeysuckle features a significant variety of cultivars primarily developed in regions with cold temperate climates, such as Canada, Russia, Poland, and Japan. These cultivars aim to meet specific criteria like productivity, cold resistance, flavor, fruit firmness, and adaptability to different climatic zones and soils. Modern selections are the result of decades of genetic improvement from native populations of the varieties kamtschatica, edulis, villosa, and emphyllocalyx.
Among the most important cultivars, the following stand out:
- ‘Aurora’: Developed by the University of Saskatchewan in Canada, it is one of the most popular Sweetberry Honeysuckle cultivars due to its sweet flavor, large fruits, and flowering compatible with various other cultivars. It shows excellent productivity and is recommended as a pollinating plant for other varieties in the same group.
- ‘Borealis’: Also Canadian, it was one of the first commercial cultivars of Sweetberry Honeysuckle. It produces large fruits with soft pulp and a sweet flavor, with early flowering. It is valued for its domestic use, although it has lower resistance to handling in commercial harvesting.
- ‘Tundra’: This cultivar features firm fruits, resistant to transportation, and balanced in flavor, making it ideal for both the fresh market and processing. Has good tolerance to pests and diseases and is adapted to regions with harsh winters.
- ‘Indigo Gem’ and ‘Indigo Treat’: Both are part of the Indigo series from the University of Saskatchewan. ‘Indigo Gem’ is widely cultivated for its sweet-tart flavor and excellent productivity. In contrast, ‘Indigo Treat’ features slightly larger fruits with a milder taste, suitable for fresh consumption.
- ‘Honey Bee’: A vigorous and fast-growing cultivar, it is often used as a pollinator due to its early flowering and compatibility with other cultivars. It produces medium-sized fruits with a neutral flavor.
- ‘Boreal Blizzard’, ‘Boreal Beauty’ and ‘Boreal Beast’: This series of Canadian cultivars is considered a breakthrough in the genetic improvement of the species. ‘Boreal Blizzard’ produces very large fruits with sweet taste and excellent firmness. ‘Boreal Beauty’ stands out for its balance between acidity and sweetness, while ‘Boreal Beast’ shows high productivity and hardiness.
- ‘Wojtek’ and ‘Zojka’: Originating from Poland, these cultivars are used both for commercial production and for domestic gardens. They produce sweet fruits and are compatible with each other for cross-pollination. They are very resistant to cold and adaptable to various European soils.
- ‘Blue Velvet’, ‘Blue Moon’, ‘Blue Forest’ and ‘Blue Hokkaido’: These cultivars have been selected in the United States and Japan. ‘Blue Velvet’ and ‘Blue Moon’ are known for their ornamental use combined with the production of edible fruits. ‘Blue Forest’ has a compact size, ideal for urban cultivations or in pots,and ‘Blue Hokkaido’ stands out for its Japanese origin and refined flavor.
The Sweetberry Honeysuckle, or honeyberry, is an excellent choice for those looking to bring beauty and functionality to a temperate or cold climate garden. With its compact stature and well-defined shrub form, it structures the space without demanding constant pruning. One of the most attractive visual features occurs in early spring, when the Sweetberry Honeysuckle blooms prematurely, even before the foliage is fully developed. The small flowers, ranging from cream to pale yellow, exude a mild and pleasant fragrance, attracting pollinators, especially native bees and bumblebees, thus enriching the garden with biodiversity.
It is a plant that fits well in beds, as a standalone feature plant, in informal groups, fruiting borders, and medium-height mixed hedges, easily composing different garden styles. The deciduous cycle offers seasonal interest, with leaf fall in autumn opening visual space and light for other species in winter, while also offering a more dramatic look.
The highlight comes during fruiting: the bluish berries, covered with a light bloom, appear between late spring and early summer, creating a beautiful and unique visual effect. In addition to being ornamental, the fruits are edible and work well in domestic orchards or ornamental vegetable gardens. The Sweetberry Honeysuckle works with gardens in more natural or even more modern styles and has the advantage of being a resilient and low-maintenance plant. It is a shrub with consistent growth and harmonious appearance, contributing to a naturalistic and seasonal look, due to its deciduous leaves, as well as attracting pollinators.
Beyond its use as a fruiting and ornamental shrub, Sweetberry Honeysuckle has attracted researchers’ attention for its medicinal effects, mainly due to its high concentration of antioxidant compounds such as anthocyanins and vitamin C. Studies indicate that the consumption of the fruits may help combat oxidative stress, reduce inflammation, and even protect the heart. There are also indications that plant extracts may help control cholesterol, liver health, obesity, and even prevent neurodegenerative diseases. While many of these studies are still in the early stages, the results are promising and reinforce the functional value of the plant in nutrition and health.
Sweetberry Honeysuckle (Lonicera caerulea) is a shrub species of cold temperate climate, adapted to a wide range of environmental conditions, making it a versatile option for cultivation in gardens and agroforestry systems. It thrives in regions with harsh winters and mild summers, being ideal for USDA hardiness zones 2 to 7.
Sweetberry Honeysuckle thrives best in full sun, although it tolerates partial shade. Fruit production is maximized when the plant receives direct sunlight for at least 6 hours daily. Regarding soil, this species is not very demanding, adapting to a variety of textures, from sandy to clay, preferring well-drained soils rich in organic matter. The ideal pH ranges from 5.5 to 7.5, but the plant tolerates slightly acidic or alkaline soils. In containers, the use of light and well-aerated potting mixes, composed of garden soil, organic compost, and coarse sand, is recommended, ensuring good drainage and moisture retention.
Sweetberry Honeysuckle planting should preferably be done in the fall or early spring, allowing the roots to establish before extreme temperatures. Seedlings should be spaced between 4 to 5 feet (1.2 to 1.5 meters), facilitating air circulation and access for maintenance. Irrigation should be regular, keeping the soil moist, especially during the first years of establishment and in periods of drought. Fertilization can be done annually, in early spring, using organic fertilizers or balanced formulations (such as NPK 10-10-10), promoting vigorous growth and fruit production.
Staking is recommended in the first years to guide vertical growth and to prevent damage from strong winds. Pruning should be performed after the harvest, removing dead, diseased, or intertwined branches, stimulating the formation of new fruiting shoots. Maintenance includes removing weeds around the base and applying mulch to conserve soil moisture. Harvest typically occurs in late spring or early summer, when the fruits turn a dark blue color and acquire a sweet-tart flavor.
Sweetberry Honeysuckle is notable for its resilience to adverse conditions. It withstands extremely low temperatures, with survival records at -52°F (-47°C), and its flowers are tolerant to late frosts. The plant also shows resistance to moderate drought, although proper irrigation enhances fruit production. It is tolerant to strong winds and can be grown in coastal regions, provided it is protected from excessive salinity.
Sweetberry Honeysuckle is relatively resistant to pests and diseases. However, it can be affected by powdery mildew (Erysiphales), especially under conditions of high humidity and inadequate ventilation. Prevention includes proper spacing between plants and pruning to improve air circulation. The use of fungicides may be considered in severe cases. Furthermore, birds such as thrushes and starlings may consume the ripe fruits, and it is recommended to protect them with nets during the fruiting period.
Propagation of Honeyberry can be done by seeds, although vegetative methods such as cutting or air-layering are more recommended to preserve the characteristics of the mother plant. Sowing should be done with fresh seeds, which germinate better after cold stratification for 60 to 90 days (about 2 to 3 months). Softwood cuttings can be collected in the summer, while hardwood cuttings are obtained in late autumn or winter, both rooting well in moist and well-drained substrates. Air-layering is effective, especially on low and flexible branches. The first fruiting generally occurs between the second and third year after planting, with production gradually increasing until it peaks between the fifth and seventh year.
