Haskap or honeyberry (Lonicera caerulea, formerly L. edulis) is a fruit-bearing shrub that has been available in nurseries a good while now, but is still relatively unknown to gardeners. Even so, it’s easy to grow and very productive: perhaps the easiest of all the cold-tolerant small fruits. Here are some details about it.
What’s in a Name?
Both growers and gardeners seem unsure about what to call this shrub. It has been called variously blue honeysuckle, blue-berried honeysuckle, sweetberry honeysuckle, honeyberry and haskap. The latter two names seem most prominent, though. Honeyberry is the most commonly used name in the United States, while haskap, from the Japanese name for the berry, is largely used in Canada.
Even the botanical name causes confusion. If you take the broadest botanical definition, L. caerulea has a circumboreal distribution, that is, it’s present throughout the northern regions of Europe, Asia and North America, dipping further south in mountainous regions. According to this view, today’s horticultural varieties have been developed from three subspecies, L. caerulea edulis, L. caerulea emphyllocalyx and L. caerulea kamtschatica, from Siberia, northern Japan and northern China.
The other view is that the subspecies are species in their own right and therefore that the true blue honeysuckle (L. caerulea) is restricted to Europe while the Asian and North American variants are various different species. That makes the cultivated varieties, which are crosses using various Asian types, intraspecific hybrids under the name Lonicera x.
I suggest letting taxonomists duke this one out: it matters little to gardeners and in this text, I’ll consider them all to be selections and hybrids of L. caerulea.
The shrub about 5 to 7 feet tall (1.5 to 2 m) tall and 4 feet (1,2 m) in diameter with small oval glaucous opposite leaves. The creamy white to pale yellow trumpet-shaped flowers appear early in the spring (late winter in very mild climates), always in pairs. Berries follow from May through June, depending on the climate. They are similar to blueberries (Vaccinium spp.) in color, that is, dark purple, but with a white waxy bloom that gives them a bluish effect. They are, however, elongated rather than round, often distinctly so in the case of modern hybrids, so no confusion is possible. Each single fruit actually formed from two separate flowers.
The long blue fruits of the L. caerulea complex are unique among honeysuckles, most of which, such as the commonly grown Tatarian honeysuckle (L. tatarica), have paired round red or orange fruits. Curiously, while the fruits of other honeysuckles are slightly toxic to humans, there is no risk in eating those of haskaps.
Harvesting has to be done a full maturity, when the fruit is purple through and through. If there is any green inside the fruit, it will be unpalatable. Fruits have a sweet tangy taste reminiscent of a mixture of blueberries and raspberries and are rich in vitamins A and C and antioxidants. In fact, they contain more antioxidants than other common temperate-climate fruit and haskap is therefore being promoted as a super food: the acai of the North, so to speak.
The berries can be used for essentially any purpose for which you might use other berries: fresh consumption, jellies, pies, smoothies, yogurt, ice cream, wines and much more. They don’t store very well, usually no more than 2 days in the refrigerator. That’s why you rarely see the berries themselves on the market, but rather derived products like haskap jam or haskap wine, although in Japan, fresh berries are widely sold. They do freeze well, though.
Haskaps/honeyberries were first imported into North America from Japan more than 60 years ago as a potential edible fruit (the Japanese called it the “fruit of longevity”), but they failed to catch on. After all, the berries were horribly bitter! Certainly no one would have called the plant “honeyberry” back then! It had some limited success as an ornamental shrub, but otherwise was essentially relegated to botanical garden collections.
However, the Russians have been working on improving this plant as a crop for over 50 years, trying to develop strains with a sweeter taste and lacking the bitterness of wild forms, largely by crossing Japanese varieties with hardier, less bitter varieties from Siberia.
Bob Bors, head of the Fruit Program at the University of Saskatchewan, took the lead in North America. Crossing haskaps is no easy matter: the modern, sweet-tasting varieties are polyploids (triploids, hexaploids, octaploids, etc.) with various combinations of chromosome numbers. Seeds from polyploid crosses tend to abort under normal circumstances, so you have to grow them in a laboratory using a technique called embryo rescue. Yes, haskaps are test tube babies!
Modern haskaps—that is, those currently available to gardeners—lack the bitterness of the wild haskaps and are now sweet enough that they can readily be eaten raw.
The Earliest Fruit
Haskaps mature very early: in May in warmer climates, June in colder ones. That’s still well before any other northern fruit. The plant flowers very early in the season too: in April or May, again depending on the climate. Since early blooming is associated with a risk of frost, you’d normally be concerned about cold damage, but remember that this plant comes from a boreal climate and can cope with cold. As a result, the flowers can handle temperatures down to 19°F (-7°C) even when in full bloom and thus readily resist spring frosts.
The plant begins to produce fruit starting in its second year and can continue to produce for 30 years and more.
Easy to Grow
There is nothing very complicated in growing haskaps: all you need is full sun (they’ll tolerate partial shade, but will be less productive) and you’re off and running!
They grow in most soils, readily putting up with clay soils and boggy conditions, for example, but, as with most crops, well-drained, rich soils give best results. In most cases, an annual application of compost will meet all their mineral needs. Unlike blueberries, which have an absolute need for acid soils, haskaps are tolerant of both acid soils and alkaline ones (pH 4.5 to 8).
Also, their cold resistance is legendary: they can survive temperatures as low as -53°F (-47°C) as long as they are fully dormant. They are therefore the northern gardener’s dream crop, readily growing in hardiness zone 2 and worth trying even in zone 1, the coldest zone where one can reasonably expect to be able to grow anything.
Space the plants 3 feet (1 m) apart for use in hedges, otherwise 4 feet (1.2 m) or more if you want to be able to maneuver around individual shrubs.
Water well the first three years, until the root system is well established. Afterwards, haskaps are relatively drought-resistant, although fruit production will be more abundant if you water them during periods of drought. Prune out older, less productive branches every 3 to 4 years to maintain a good harvest.
Haskaps are self-sterile: the pollen of another cultivar is necessary to ensure fecundation, otherwise there will be no fruit. It is therefore important to plant at least two varieties nearby. Various species of bees, both imported and native, ensure pollination: avoid using toxic pesticides when bees are in the area.
Haskaps are resistant to most insect pests, but can occasionally be affected by powdery mildew during the summer, after harvest. This disease is mostly an aesthetic problem and doesn’t reduce the plant’s productivity, but still does cause concern among beginning growers. Fortunately, modern cultivars are much more resistant to powdery mildew than earlier introductions.
So far, so good, but, as with so many other small fruits, you’ll still have to deal with fruit-eating birds when the fruits are ripe. They can empty a shrub of all its fruit in less than 24 hours! It may therefore be necessary to install bird netting to keep them at bay.
Growing Haskaps in Warm Climates
The haskap is essentially a northern crop. It will not thrive where it doesn’t have a prolonged period of freezing or near freezing temperatures (less than 45°F/7°C). Its chilling requirement is about 750 to 1000 hours of cold, depending on the variety.
In mild climates, Russian and Canadian cultivars are not the best choice. Their tendency to bloom early may backfire: they can be “fooled” into thinking winter is over and start to bloom too early, when no bees are present for pollination, resulting in a crop failure. Slower-to-bloom Japanese cultivars are more amenable to growing in mild climates.
The haskap also prefers a relatively cool summer. Where temperatures regularly exceed 86°F (30°C) for more than a week, the shrub tends to go into early dormancy. Although this is after harvest, it can be disconcerting to see its leaves turn yellow, then brown and drop off in mid-summer. Many gardeners mistakenly believe the plant is suffering from a lack water or from some kind of disease (indeed, heat stress does tend to bring out powdery mildew), but it’s best to think of this as just being its normal reaction to excess heat. The best advice in such a case is simply to let the plant take care of itself. As long as it receives the winter chill it needs, it will be back in the following spring with a new load of fruit!
That said, there is a limit to how much prolonged heat a haskap will take. This plant will probably always be a better choice for hardiness zones 2 to 6 than 7 to 9.
If you buy plants locally, the choice of varieties will likely be limited… unless you have a small fruit nursery nearby. If you’re willing to order plants by mail, though, that will open up a lot of possibilities. In the US, try Haskap Central Sales Ltd (actually a Canadian company, but they sell plants to the US) or Berries Unlimited. In Canada, try Green Barn Farm or Vesey’s.
The quality of the cultivars from the University of Saskatchewan program is pretty much blowing the older Russian varieties out of the water. Look for such varieties as ‘Aurora’, ‘Borealis’, ‘Tundra’, plus the ‘Indigo’ series (‘Indigo Gem’, ‘Indigo Treat’, ‘Indigo Yum’). There is a lot of buzz about the two most recent cultivars released from the program, ‘Boreal Blizzard’ and ‘Boreal Beauty’, which produce much larger and more abundant berries than older cultivars, but they may be in limited supply for a few years yet.
Don’t entirely ignore Russian varieties like ‘Honeybee’, ‘Cinderella’, ‘Blue Belle’ and ‘Berry Blue’. The berries they produce are smaller and not as sweet, but they are excellent pollinators for Saskatchewan varieties and are often used mostly for that purpose.
Japanese varieties are less hardy than Saskatchewan and Russian haskaps (about zone 4), bloom later, and bear smaller fruit. Recent releases no longer have the bitterness associated with the first introductions and, in fact, some claim they are the sweetest of all haskaps. They are the ones to try in more moderate climates (zones 6 and 7). Yezberry® Maxie™ and Yezberry® Solo™ are two of the newer, sweeter Japanese varieties that are gaining in popularity.