The conventional kiwifruit is fine in mild climate, but you need extra-tough kiwis where winters are cold. Photo: homesteadersonline
Who wouldn’t recognize a kiwifruit, the goose egg-sized fruit with a fuzzy brown outer skin and delicious green flesh inside? They’re sold in supermarkets everywhere all year long. The fruit comes not from a tree, like an apple or cherry, but form a vigorous twining woody vine: the kiwi, kiwifruit or Chinese gooseberry: Actinidia deliciosa, formerly A. chinensis.
While the kiwifruit is abundantly found in supermarkets ready to eat, it’s not all that hardy. It’s limited to hardiness zones 8 to 9; sometimes, with special care, to zone 7. Some of the readers of this blog can grow it, for example those in the southern US or on its west coast, milder parts of Europe and temperate regions of Afric, Asia, Australia and New Zealand, but most live in cool to cold temperate climates. The best you could do would be to grow this vigorous, domineering plant in a greenhouse. Good luck with that!
Fortunately, there are other species of Actinidia, ones with small fruit often called kiwiberries, that are very hardy and which can easily be grown in outdoors in all but the coldest climates, in particular A. kolomikta and A. arguta. Yet, they don’t absolutely require subzero winters, so can also adapt to mild climates. In other words, these hardier kiwis can be grown by just about anyone outside the tropics. Maybe there is a place for a few of these hardy kiwis in your garden?
Hardy kiwis are vigorous climbers with twining woody branches that twist around their support. They therefore require a solid support: a trellis, pergola, arbor or other. You can also let them climb a tree, but then, how will you harvest the fruits? Especially since kiwi vines can reach more than 35 feet (10 m) in height!
Another possibility is to grow them as large shrubs, 6 to 10 feet (2 to 3 m) in height and as much in width. You can easily create this effect simply by regularly snipping off any branches that grow too long. By preventing the plant from climbing, it will reluctantly take on a shrublike form.
Kiwifruit blooms profusely in the spring, producing small, fragrant, but relatively inconspicuous white flowers, since they are produced among the leaves and are therefore rather hidden. They are best appreciated when grown on a pergola or arbor where they can be admired from below. Suddenly the otherwise hidden flowers dangle down over your head by the hundreds if not the thousands! Quite a display!
It Takes Two To…
However, it’s very important to plant hardy kiwis of both sexes. That’s because the male and female flowers are produced on separate plants (the’re dioecious). So, you need 1 male plant for a maximum of 9 female plants; otherwise you won’t have fruit.
Hardy kiwis can be grown in the sun or shade in almost any well-drained soil, but preferably in rich and rather moist conditions, as that gives the most abundant fruits. A kiwi plant can easily live 150 to 200 years. Just plant yours in spring or fall … and wait patiently, as, like most fruiting plants, they usually take a few years before they start to produce fruit.
The fruits of hardy kiwis are small and produced in clusters, like grapes. Since they aren’t covered with fuzz, there is no need to peel them: just pop them in your mouth and eat them whole. They ripen in late summer or fall and are often difficult to see, as most are green, almost the same color as the foliage. Few change color when ripe, although there are some exceptions to that rule, as some varieties of Actinidia arguta, like ‘Mirzan’, do turn red at maturity.
Usually, the best way to tell the fruits are ripe is to touch them. They soften a bit at maturity, so a bit of a squeeze will tell when to harvest.
Two Kiwis That Tolerate the Cold
The hardiest kiwi is the so-called arctic kiwi, A. kolomikta, native to northern Asia, particularly Siberia and China. It doesn’t really grow in the Arctic (the common name is slightly exaggerated), but still, plants in the northernmost part of its range are not that far from the Arctic Circle. Plus, it can take temperatures down to -40 °F/C.
Oddly, I keep seeing websites that underestimate its hardiness: commonly, they give zone 4. Calculate instead hardiness zone 3 or even, for some cultivars, zone 2. In other words, if you can garden in your climate, you can likely grow this plant. (My apologies to the very rare people who do garden in zone 1!)
The arctic kiwi is actually more commonly grown as an ornamental plant, because its leaves are often abundantly variegated pink and white.
Unfortunately for fruit-loving gardeners, most of the arctic kiwis sold in garden centers are male plants, the claim being made that male plants have the most colorful foliage. In fact, though, leaf coloration seems to be spread unevenly through both male and female clones of hardy kiwi. Many females are variegated too and some male clones, barely so. However, the most heavily variegated cultivar on the market is indeed a male clone, often sold with no name or under the cultivar name ‘Arctic Beauty’. If you grow arctic kiwis from seed and choose plants with the greatest variegation, you’ll inevitably find female plants among the lot. So, if you want to play the role of hybridizer and produce a female plant with brilliantly colorful leaves, go for it!
The arctic kiwi begins to produce fruit at a relatively young age, after about 3 years. The fruits ripen early, in August or September, as befits a fruit adapted to cold climates where summers are often short. The main flaw of this kiwi, though, is that the fruits drop off the plant soon after ripening, so it’s easy to miss the harvest window if you are not there at just the right time.
As mentioned, the most common cultivar is the heavily variegated male cultivar ‘Arctic Beauty’, but there are other male clones. And, of course, you’ll want a male plant to pollinate your females. Among the female cultivars are ‘Aromatnaya’, ‘Krupnopladnay’, ‘Pavlovskaya’ and ‘Sentyabraskaya’ (‘September Sun’).
If the names seem Russian to you, you’re right. This fruit has been, until recently, largely developed in Russia.
Another kiwi to try in colder regions is A. arguta, often referred to simply as “hardy kiwi”, although it’s not nearly as hardy as the arctic kiwi.
Its foliage is entirely green, it’s so is less ornamental than the foliage of the arctic kiwi, and it’s slower to start producing fruit, usually only doing so after 5 to 9 years. It’s not actually that well adapted to truly cold climates, either. Perhaps zone 4b, max. North of that, the late-maturing fruits (they often don’t ripen until the end of September or October) are often killed by frost. If frost threatens yours, harvest them: they will continue to ripen indoors, but won’t be as sweet as fruits that ripened on the vine.
Male cultivars for pollination include ‘Weiki’ and ‘Meader’, but are often sold without a name other than “male”. There are dozens of female cultivars, including ‘Ananasnaya’ (‘Anna’), ‘Dunbarton Oaks’, ‘Geneva’, ‘Ken’s Red’ and ‘Mirzan’.
The Least Hardy Hardy Kiwi
The most popular hardy kiwi, widely sold everywhere and often the only hardy kiwi offered, is ‘Issai’, a Japanese hybrid. However, it doesn’t live up to its reputation, especially in cold climates, and, in many situations, is a very poor choice indeed.
You hear a lot about the advantages of ‘Issai’ and at least one is true. It’s claimed to be able to set fruit when very young. Indeed, ‘Issai’ means “first year” in Japanese. Actually, it usually takes 2 to 3 years to produce its first fruits, but that’s still very young for a kiwifruit. So, give it full points for speed to first fruiting.
Next, merchants often claim it’s both male and female and self-pollinates. Thus, it’s a space saver: you only need one plant to get fruit. In fact, though, ‘Issai’ is 100% female, but somewhat parthenocarpic: it can produce a limited amount of fruit without pollination. However, if you want abundant production, you still need to plant a male A. arguta plant as a pollinator. So, take off a few points there.
And thirdly, the claim that most bothers me, since I live in a colder zone myself, is that ‘Issai’ is a hardy kiwi. In fact, it is not a true hardy kiwi (A. arguta), but a hybrid between the hardy kiwi (A. arguta) and the subtropical russet kiwi (A. rufa). It seems to have inherited enough subtropical genes from its A. rufa parent to make it unsuitable for growing beyond zone 6. North of that and it gets killed back by the cold most winters or, at least, its dormant flower buds are killed, and therefore it neither blooms nor fruits most years. Still, the label says zone 4 and gardeners in zones 4 and 5 plant it, confidently awaiting a good harvest. Most never get to taste a single fruit. Take off any remaining points there!
You’d think garden centers in colder climates would pull it from their shelves and only offer truly hardy varieties, but no such luck. Most still offer ‘Issai’ to gullible gardeners and, indeed, it’s generally the only “hardy” kiwi they sell. I must point out that this happens not only in those know-nothing box stores that regularly sell climatically inappropriate plants, but in local garden centers and nurseries in cold climates that should know better. Shame on you for scamming your clients!
In short, in cold climates, zones 2 to 5, ‘Issai’ isn’t as much a kiwifruit as a real lemon!
Where to Find Hardy Kiwi Plants
Sadly, you won’t often find acceptable hardy kiwis in local garden centers. You’ll have to turn to a specialist fruit nursery and very likely will need to order them by mail. Here are a few sources:
Good luck with your cold-climate kiwis! They can be truly easy-to-grow plants with abundant and delicious fruit that any gardener would be proud to grow … but you still have to choose the right ones!