Horticulture Magazine

How To Grow Kiwis

flowers of the kiwi plant

Kiwi Overview

Official Plant NameActinidia
Common Name(s)Kiwi
Plant TypeFruit / Climber
Native AreaChina
Hardiness RatingH4
ToxicityEdible Fruits
FoliageDeciduous
FlowersCreamy white flowers
When To SowMarch, April, May
Flowering MonthsJune
Harvesting MonthsAugust, September
When To PruneJanuary, February, July
Sunlight

Preferred
Full Sun

Exposure
Sheltered

Size

Height
8 – 12M

Spread
2.5 – 4M

Bloom Time
June / July

Soil

Preferred
Loam, sand

Moisture
Well drained

pH
Any

Matching the rise in popularity of the Kiwi fruit over the past few decades is the recent ascendancy of Kiwi as a garden plant. These come in a surprising array of fruiting vines which can be grown from coast to coast in the U.K. Admittedly, maintaining Kiwi vines requires time and skill but think of the reward: a bounty of garden-grown luscious Kiwis.

Kiwis are often thought of as a fruit native to New Zealand; an exotic fruit with not very many types. These are both misconceptions. The types of Kiwis that we commonly buy at the store are native to China and were introduced to New Zealand as late as 1906. It is not exotic as so many hybrids and cultivars exist that they can be grown in hardiness zones from below H7 through to H3.

The fuzzy-skinned green Kiwi that we know and love so well is Actinidia deliciosa. It originates in the south-eastern coastal regions of China. A related smooth-skinned species that has golden flesh, Actinidia chinensis, is native to the Yangtze Valley in northern China. 

Even the name ‘Kiwi’ or ‘Kiwifruit’ is of recent vintage: it was in 1962 that the rather contrived name of ‘Kiwifruit’ was given to the Chinese plant’s fruit by New Zealand producers. Until then, since the early 1900s, it used to be known in the Western World as ‘Chinese Gooseberry.’ As for the Chinese themselves, they have always known it as ‘Strawberry Peach.’

The Actinidia genus contains about 75 species, plus many hybrids and cultivars of the prime fruiting species. Comprising of shrubs and vines, all of them bear fruit from the size of a large grape to the relatively large fuzzy Kiwi. The vines that bear the smaller fruit are hardy – some are very hardy – and these are native to north-eastern Russia. These vines also exhibit different foliage. ‘Tender Kiwi’ vines’ leaves are usually rounded or heart-shaped while hardy Kiwi vines’ leaves are often serrated and oblong, and some species’ leaves are decorative and variegated, with red, pink, and white blotches and segments.

kiwifruit farm in Bay of Plenty, New Zealand
A Wonderful View of a Kiwi Plantation in New Zealand’s Bay of Plenty

Characteristics of Kiwis

The ‘Fuzzy Kiwi’ fruit that most of us are familiar with is that of the ‘tender Kiwi,’ usually Actinidia deliciosa, sometimes Actinidia chinensis. This fruit stores and ships well and conserves its freshness. The fruit of the hardy Kiwi, on the other hand, cannot be stored and shipped, being very perishable. Many people prefer this latter fruit because it is sweet instead of tart or tangy, and its smooth and thin skin is edible, like that of an apricot.

Kiwi vines are traditionally dioecious – they bear either male or female flowers. Only the female vines bear fruit whereas male vines are necessary for pollination. The vast majority of commercial named cultivars are either male or female though a few occur in both male and female forms. During the past couple of decades some reliable monoecious self-fertile cultivars have been developed. 

Flowers are white or creamy with the male ones having very prominent yellow anthers. They are more or less bowl shaped with a full look about them. All varieties’ flowers are pleasantly fragrant with the sweetness and intensity of the fragrance varying by variety.

Kiwi is considered a superfood, with some justification. It supplies dietary fibre and contains the enzymatic protease Actinidin which aids in digestion. It contains bumper amounts of Vitamin C, and is also a good source of Vitamins E and K, Folic Acid, Potassium, Copper, and anti-oxidants.

Growing Kiwi vines is not difficult but for good yields the female vines – besides being adequately pollinated – need to be trained and correctly pruned. All said, it is a technical gardening endeavour that requires time and commitment.

kiwi plant climbing a black gazebo in a Mediterranean setting
A Kiwi Vine Climbs up a Gazebo in a Sunny Mediterranean Setting

Background and Origins

Actinidia deliciosa – Fuzzy Kiwi – has been known in various Chinese regions for centuries though in the Western World it is commonly associated with New Zealand. As it happens, both the United Kingdom and the United States had just beaten out New Zealand to the ‘Kiwi’ by two or three years!

The R.H.S. had received through its agent dried specimens of Actinidia deliciosa for purposes of study as far back as 1847. It took over half-a-century for Great Britain to obtain seeds, which it did in 1900. These seeds were successfully grown and the vines produced Kiwis in Great Britain in around 1909. Kiwi-wise, the United States tracked Great Britain. In 1904 an American consul in China sent seeds to the U.S.D.A. who did well enough to grow vines that yielded Kiwis in 1910.

New Zealand got its hands on Fuzzy Kiwi seeds in 1906 and was up and running with the fruits by 1910. However, New Zealand then just ran away with the fruit, appropriating it. Growers established several plantations as the fruit rose in popularity domestically, and then became a hit with American troops in the country in the World War II years. In the 1950s the country started exporting the fruit which at that time was not even called ‘Kiwifruit’ or ‘Kiwi.’ 

Today, though China is by far the biggest producer of Kiwis, New Zealand is by far the biggest exporter of the fruit. While the ‘Kiwis’ provide just over half of the world’s Kiwi exports, the native country of the fruit does not rank even in the Top Ten Kiwi-exporting countries.

The major centres of Fuzzy Kiwi horticulture have been New Zealand and California. However, Russia is the little-acknowledged leader in Hardy Kiwi horticulture, having developed a number of high-quality cultivars.

a kiwi plantation in New Zealand
One of New Zealand’s Many Kiwi Plantations

Varieties

Believe it or not, there are dozens of Kiwi varieties. In this section we present two ‘Fuzzy Kiwi’ female vines, two ‘Fuzzy Kiwi’ self-fertile vines, a ‘Fuzzy Kiwi’ male vine, and a Hardy Kiwi self-fertile vine.

A. deliciosa ‘Hayward’ is a female vine that may just as well be called ‘Old Reliable’. The Kiwis that most of us have eaten and enjoyed are from this tried-and-trusted cultivar. It is by far the most abundant Kiwi cultivar in New Zealand and Italy’s plantations and is the only one used by California producers. It is not particularly high-yielding but the fruit is of top quality. The hen’s egg-sized fruit has green flesh that is sweet, tart, and tangy. You will need multiple ‘Hayward’ vines with one male vine to reap a good harvest of fruit.

A. deliciosa ‘Bruno’ has quite a misleading name, for this is a female vine. The fruit is of a dark brown colour and its ‘fuzz’ is a little bristlier than the fruits of ‘Hayward.’ Compared to other female vines it is late to flower and, therefore, to fruit. While the fruit is of excellent quality this vine is also valued for being especially prolific.

A. deliciosa ‘Jenny’ is renowned as a very robust climber that has particularly pretty foliage and even stems. This frost-tender vine produces fruits about the size of small eggs in mid-autumn. It is especially easy to grow as a compact, self-fertile cultivar that has proven itself. For a self-fertile vine it is comparatively high-yielding. Also, the fruit is of excellent quality as the flesh has a wonderful consistency and is on the sweet side.

kiwis on a tree with a white background
Fuzzy Kiwi Fruits with Heart-Shaped Leaves

A. deliciosa ‘Solissimo’ is a much more recently-developed self-fertile cultivar and as such cannot be called a proven quantity. However, it is rapidly rising in popularity and has even come into commercial use. It is a little hardier than other A. deliciosa cultivars. Though not especially productive the fruits it produces are massive, being much larger than the norm. It is also good on the palate as the sweet-scented flesh is very flavourful. 

A. deliciosa ‘Atlas’ is considered to be the male cultivar of choice. It is a vigorous climber and produces blossoms through the summer. These creamy flowers display prominent golden-yellow stamens whose strong, sweet scent attracts bees and butterflies in droves. It pollinates all female A. deliciosa varieties.

A. arguta ‘Issai’ is for those U.K. residents who want to grow Kiwis but whose location makes growing traditional Fuzzy Kiwis a fraught undertaking. On the other hand, even if you live in Cornwall you may want to grow ‘Issai’ simply because you prefer the smaller, sweeter, non-fuzzy fruit of Hardy Kiwis. Be that as it may, this cultivar is so super-hardy that it can be grown in Norway. It is a very high-yielding vine, producing nearly a thousand fruits per season. On top of it, this is a self-fertile variety.

green fuit on a Actinidia Issai tree
The ‘Issai’ Vine is Very Hardy and Bears Smooth Kiwis

Habitat and Growing Conditions

The various species of Actinidia are native to a swath of land from India and the Himalayas arcing south-east to steamy Borneo and north-east to cold Manchuria and frigid Khabarovsk. As one might expect, these different species’ respective hardinesses spans six hardiness zones. The genus includes frost-tender species that are good for U.S.D.A. Zone 8 through ‘super-hardy’ vines that are hardy right down to U.S.D.A. Zone 3 – which is so frigid that there is no R.H.S. ‘hardiness’ equivalent for it.

These many species of Actinidia grow in regions where the soil pH is also very variable, ranging from Moderately Acidic to Moderately Alkaline!

The species of paramount interest to us, Actinidia deliciosa, grows wild in the south-eastern coast of China’s Zhejiang province in scrubland with soil of varying quality and where these plants are not infrequently exposed to – surprise! – fairly stiff nor’easterly winds. The black soil is of a fertile and crumbly type under which is a stony subsoil. In this region of China the soil pH is Moderately Acidic to Slightly Acidic.

How to Grow Kiwi

This section pertains to tender Kiwi vine varieties which are derived from Actinidia deliciosa. You can grow these outdoors in most regions of the United Kingdom but if you live in the Scottish Highlands or a particularly cold region of England, such as the vertical belt from Carlisle to Sheffield, you will have less trouble with a hardy Kiwi cultivar, unless you grow tender Kiwi vines in a greenhouse (though if you use traditional dioecious vines, fertilizing the flowers will be a problematic chore).

In growing Kiwis, soil pH is not of much importance while other soil-related factors are of great importance. That said, the optimal soil pH is Moderately Acidic to Slightly Acidic; between pH 5.6 and 6.5.

The soil should be laid deep and drain very well. It should be a sand-based, light, friable loam which should include chalk and may also be amended with compost but should have minimal or no clay.  You may work in just a little bonemeal, fishmeal, or both into the soil itself; do not ‘fertilize’ the roots with it. It will act as a slow-release fertilizer high in Phosphorous and Potassium.

As any waterlogging is very detrimental to these vines, to ensure good drainage the ground may be worked into mounds or ridges into which Kiwi vines can be planted.

The site should be where the plants are sheltered but enjoy full sun. Ideally the vine should be positioned against a wall that shelters it from the north-east and leaves it with a south-westerly exposure. Spring frosts retard both flowering and fruiting. The vine can tolerate a frost of up to about -7° centigrade; anything colder and it will likely suffer adverse effects.

Vines are best planted out in early spring, two to four weeks after the last frost.

If you intend to grow your Kiwis the traditional way with dioecious vines, go with one male vine and four or five female ones. These should be sited close to one another. Atlas and Hayward are the cultivars of choice. If you want to use a monoecious vine, which is a godsend if you have limited space or must grow your vine in a greenhouse where pollination will be next to impossible, Jenny is a top choice for the U.K.; Solissimo is an excellent alternative.

Depending on the varieties and other variables, it takes two to five years, typically three, for vines to produce fruit.

white blooming kiwi flowers
Kiwi Vines Also Provide Attractive Rounded Leaves and Cream-White Bowl-Shaped Flowers

Water regularly so that the soil is kept moist. It should not stay wet. Vines have increased water requirements soon after transplanting, when they are young, and when they are setting fruit. In wet parts of the country, established Kiwi vines may well get enough water from the rains.

Female vines have to be grown and trained on trellises (though one ought to do so for male vines too). A-frame pergolas are even better as the vine is trained and opened on it in such a way that yields are boosted and harvesting is easier. The vines also must be pruned with skill and correctness to maximise yields.

Train and prune each vine initially so that there is a single leader and about four arms or canes. (These will be refreshed about every three years.)

When the leader gets to the top of the frame, pinch it to halt further growth. You should then have three or four strong lateral arms initially. These will become the first fruiting arms. Train these arms at an angle on the trellis and prune any new shoots.

The aim is to have a single leader, and to maintain fruiting arms that are spaced from 50 to 70 centimetres apart on the vine. The arms that are one or two years old bear the most fruit; arms bear less fruit as they age.

In summers, deadhead spent flowers and thin them if the bloom is excessive. Train new shoots on the trellis to grow above and away from foliage so that they get the right start.

In winters, prune the fruiting arms judiciously. Prune arms that are three or more years old (provided you have a sufficient number of young fruiting arms). Maintain the correct spacing between these fruiting arms, and prune excess new shoots. Strive to keep a good balance of new shoots and one- and two-year arms. At this time, train the arms to grow above and away from the foliage.

Water the vine only now and then in winter.

In winter keep an eye on the weather forecast. If a prolonged freeze or repeated frosts are expected, protect the main vine and leader right from the soil line with horticultural fleece.

Every alternate year, you may mix in a touch of bonemeal, fishmeal, or both into the soil away from the roots each spring and then fertilize with nitrogen, or annually apply a little 10-10-10 slow-release fertilizer. Avoid using ‘regular’ fertilizer on Kiwi vines.

kiwi fruit hanging from a support structure
A Kiwi Vine’s Horizontal Fruiting Arms Supported by a Framework

Harvesting Kiwi

As the flowers form into fruit – fruit set – and thereafter until the fruits are harvested, increased watering is beneficial. At this time the vine may be watered every other day.

If you see an abundant setting of fruit or even abundant flowering (on the female vines, not the male vine), some thinning may be a good idea to ensure that the fruits you harvest are of the highest quality. Such thinning is dictated to a great extent by the cultivar; for example, Hayward will benefit from it but Issai will usually not need it.

Where Kiwi in the U.K. is concerned, the best plan is to leave the fruit on the vine to mature (unless slugs or birds force your hand) through the autumn, aiming to pick it as late as possible. When the first ‘real’ frost is forecast, collect all the fruit.

Kiwis will keep indefinitely in the fridge. If you have to ripen them, place them in a sunny spot in the kitchen or tightly wrap them in two or three layers of newspaper or cotton cloth.

We believe that Actinidia deliciosa – ‘Fuzzy Kiwi’ – eaten peeled and raw, is most enjoyable when the fruit when pressed from around the peduncle attachment does not feel at all soft, feels firm-to-hard, with about the firmness (or hardness) of a softwood branch. The flesh of such a fruit that feels raw to hand pressure will not only be just-ripe but will have a very appealing consistency that is not overly-soft or mushy but will have a bit of ‘bite,’ and will be bursting with flavour – sweet, tart, and tangy all at once.

Actinidia deliciosa fruits
Kiwis Ready for Harvest in Someone’s Garden – Why Not Yours?

Common Diseases and Problems

Kiwi plants are remarkably free of pests and diseases in the United Kingdom.

If your garden or ground has any history of honey fungus, then you should avoid growing Kiwi as it is very susceptible to this dreadful plant disease.

Other than that, the only real threat, such as it is, is from slugs. Even this will be precluded if your vine is on a sun-soaked wall or a type of trellis which cannot be navigated by these nuisance pests.

Where to Get Kiwi Vines

A few of the more popular cultivars like Hayward and Jenny can be found as potted plants at some of the bigger nurseries and garden centres. A more extensive selection of cultivars is available at a limited number of fruit tree specialists. These merchants are easily found online and they are your best bet for obtaining a quality vine. Young vines are supplied as potted plants and in bare root form. 

slices of kiwi fruit layered on top of one another
You’ve Been Buying Them, but you can Garden-Grow Them!

In addition, you can ‘get’ Kiwi vines yourself by propagating them from softwood cuttings. Mid-spring is the ideal time to do so.

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