<em>Actinidia</em>, kiwifruit tree: planting, pruning, harvest

Description and botany

Kiwi (Actinidia chinensis or deliciosa), also called kiwifruit-tree, Chinese gooseberry, or even “plant mouse”, is a climbing fruit bush belonging to family Actinidiaceae, like its cousin the Kiwai or Siberian Kiwi (Actinidia arguta) which bears smooth-skinned fruits.

Kiwi originates from temperate regions of China, not New Zealand, which nevertheless remains its main exporting country. Kiwi arrived in France, in Nice in 1904, and has since acclimatised widely, mainly in Landes, the Midi and Corsica.

About 30 kiwi species are recognised but only 5 produce edible fruit and are grown for this purpose in France. Among them, Actinidia deliciosa whose fruits have a villous skin, and its numerous cultivars including some self-fertile ones such as ‘Jenny’ or ‘Solo’, the best-known. Species Actinidia chinensis produces smooth-skinned kiwis, while Actinidia arguta, also called “Kiwai”, bears fruits smaller than traditional kiwis that are eaten with the skin.

This vigorous shrubby liana with woody climbing stems clings to any support thanks to its tendrils. Its long, sinuous and voluble stems can grow by 3 m per year to reach 6 m in height, sometimes more if conditions are favourable, and about 4 m wide at maturity. Young shoots with reddish bark are covered with a reddish down. Kiwi shows good longevity and can live between 50 and 100 years.

Actinidia’s foliage is noteworthy. Shoots bear large, broad deciduous, alternate leaves 8 to 20 cm long. Ovate or heart-shaped, they are entire, with prominent, paler veins and dentate margins ending in bristles. Medium to dark green above and paler beneath, they are for the most part villous and covered with a fine down. Actinidia kolomikta, the arctic kiwi, is an ornamental species distinguished by truly decorative leaves, tricoloured, green variegated with pink and white on their lower half.

Various leaves: Actinidia deliciosa and Actinidia kolomikta (ornamental kiwi)

On this abundant foliage, in May–June, after only the fourth or fifth year of cultivation, small flowers open singly or in groups of three in the axils of the leaves on shoots from the previous year. These scented flowers have five petals, cream-white or creamy-yellow depending on cultivar. But how to recognise a male and female kiwi tree?

Most Actinidia species are dioecious, meaning they require presence of a male plant nearby to allow pollination by bees. However, new varieties of Actinidia are self-fertile (male and female flowers on the same plant): a single tree is enough to obtain fruit. Sex distinction is simple by examining flowers: female flowers, 3 to 4 cm in diameter, are solitary and bear short stamens surrounding white stigmas, while male flowers are smaller, grouped in cymes of three and bearing numerous fertile stamens, very prominent, golden and powdery.

Only female plants produce fruit. This flowering is followed by formation of numerous tasty ovoid summer berries 3 to 9 cm long: kiwis. Appearance, colour, size and flesh vary between species and cultivars.

About the size of an egg in Actinidia deliciosa and Actinidia chinensis, fruit size does not exceed that of a gooseberry or a large grape in Actinidia arguta or Kiwai. The thin skin is downy, covered with short brown hairs in Actinidia deliciosa, while it is so smooth in others (Kiwai) that peeling is unnecessary. While classic kiwi has light brown skin enclosing green almond-coloured marbled flesh, some varieties produce golden fruit (Actinidia chinensis ‘Minkigold’), or deep red as in Siberian Kiwi ‘Ken’s Red’ or in Actinidia deliciosa ‘Kiwi Wonder®’.

Kiwi tree flowers and fruits

This juicy pulp, more or less sweet, contains around 1,000 small black seeds at its centre. Its tangy flavour recalls green apple and is rich in fibre, vitamins C and E, carotin and minerals such as magnesium and calcium. Kiwai’s flavour is closer to gooseberry and is sweeter than traditional kiwi.

Contrary to common belief, Kiwi is very hardy, able to withstand temperatures down to −15°C, but young shoots are vulnerable to severe spring frosts. Actinidia arguta, also called Siberian Kiwi, is perhaps the hardiest, tolerating down to −20°C. Kiwi enjoys sun or partial shade and prefers a cool, rich, light and well-drained soil, non-calcareous. This vigorous and hardy liana can be trained against a wall or pergola, or will climb a tree.

Name “Kiwi” refers to that New Zealand endemic bird, whose plumage resembles that of the fruit.

Self-fertile or dioecious species?

Most new varieties of kiwi (or kiwifruit vine) are self-fertile (‘Solissimo’, ‘Jenny’ or ‘Solo’): a single young plant is enough to produce fruit, others, however, require the presence of a nearby male companion to set fruit. In that case, you must plant one male young plant or you will have no kiwifruit. Male young plants are markedly more floriferous than female young plants; they do not produce fruit but pollinate female young plants: a single male young plant can pollinate about 5 to 6 female young plants at a distance of 5-6 m.

Main species and varieties

Les duos

Nos variétés autofertiles

Autres espèces intéressantes

Siberian Kiwi Duo 'Ken's Red' (female) + 'Issai' (pollinator)

Variety 'Issai' with small green fruits is self-fertile and will act as pollinator required for fruiting of 'Ken's Red', which bears small fruits with purplish-red skin and flesh.

• Flowering time July, August
• Height at maturity 5 m

See the product sheet

Duo of Female 'Hayward' and Male Pollinator 'Atlas' Kiwi Plants

Planting these two kiwis close to each other yields large, flavoursome fruits with green flesh and good keeping quality.

• Flowering time July, August
• Height at maturity 6 m

See the product sheet

Hardy Kiwi Geneva (self-fertile) - Actinidia arguta

Only self-fertile Kiwi arguta variety. This kiwi with smooth skin is eaten without peeling! Flesh sweeter and richer in vitamins than common kiwi.

• Flowering time July, August
• Height at maturity 5 m

See the product sheet

Kiwi Plant Solissimo (self-fertile) - Actinidia chinensis

Single plant provides abundant harvest. Variety very productive!

• Flowering time June, July
• Height at maturity 6 m

See the product sheet

Kiwi Plant Jenny (self-fertile) - Actinidia deliciosa

Attractive self-fertile variety producing small fruits with green flesh. Train along pergola, trellis or arbour.

• Flowering time July, August
• Height at maturity 6 m

See the product sheet

Yellow Kiwi Plant Minkigold (female) - Actinidia chinensis

Variety producing golden kiwis with yellow flesh and a slight apple scent. Female plant requires proximity of male plant 'Minkimale' to allow pollination.

• Flowering time July, August
• Height at maturity 6 m

See the product sheet

Kiwi Plant Golden Delight (female) - Actinidia chinensis

Arguably the tastiest kiwi! Produces golden kiwis with particularly sweet yellow-gold flesh. Requires Kiwi Golden Delight (male) to set fruit.

• Flowering time July
• Height at maturity 5 m

See the product sheet

Yellow Kiwi Plant Kiwi Wonder (female) - Actinidia deliciosa

Unique variety with thin, hairless skin that yields yellow fruits with yellow flesh and a red centre, very sweet and non-acidic in flavour. Requires proximity of a male plant to set fruit, such as male cultivar Tomuri.

• Flowering time June, July
• Height at maturity 5 m

See the product sheet

Hardy Kiwi Ken's Red (female) - Actinidia arguta

Non-self-fertile variety producing red kiwiberries with slightly purplish flesh, eaten with the skin. Female plant requiring nearby male plant to allow pollination.

• Flowering time July, August
• Height at maturity 5 m

See the product sheet

Planting

Where to plant kiwi?

Perfectly hardy, kiwi can withstand temperatures around -15 °C. However, it is sensitive to severe late frosts, since its buds freeze at -4 to -5 °C. Give it a spot sheltered from cold winds and spring frosts that can scorch its young shoots and damage its flowers. Avoid in particular walls exposed to north or east.

Kiwi prefers sunny but not scorching positions, especially in southern France. It likes rich, deep soils, not too calcareous (which can cause chlorosis), well-drained and remaining cool at depth. It dislikes waterlogged, oxygen-poor soils that retain water in winter. It will naturally take up position on a raised bank if ground holds too much water in winter.

Kiwi needs space to establish, especially since for non-self-fertile species two specimens (a young female plant and its pollinator) are necessary for fruiting.

Kiwi requires training: provide a sufficiently sturdy support 5 to 6 m long and 3 m high so its stems can climb.

It can be trained against a wall with strong wire, on wire mesh, on a pergola, on a well-exposed arbour, or run between two tree trunks. It naturally finds a place in an orchard.

When to plant?

Plant kiwi ideally in autumn, from October to November. In regions with harsh winters, plant preferably in spring. In temperate zones, our container-grown young plants can be planted year-round outside frost periods.

How to plant?

In case of non-self-fertile varieties of kiwis and kiwaï, plan to plant at least one male young plant for five female young plants, respecting a planting distance of 2 to 3 metres between plants.

Planting:

• Loosen soil to 80 cm in all directions
• Dig a hole 3 to 5 times wider than rootball
• Spread a layer of gravel at bottom of planting hole
• Bury rootball leaving collar at soil level
• Backfill with a mix of garden soil, sand and compost-enriched potting soil with a generous handful of well-rotted compost
• You can also add horn meal
• Provide a support to help its stems climb
• Firm soil and water copiously then regularly during first year after planting

Kiwi trained on wire mesh

Maintenance, pruning and care

Kiwi prefers soils that always retain some moisture: it needs water. Water regularly in summer and during first three years. In periods of high heat, water 1 to 2 times per week. Mulch the base to keep it cool. Kiwi needs a fertile soil to produce well: each spring, at flowering, make an application of fruit-tree fertiliser and add compost in March at base of kiwi.

Protect the base with a good layer of straw for first three winters.

Carry out shallow hoeing to keep base clean and prevent germination of adventive plants.

Train the liana as it grows.

Pruning kiwi and kiwaï:

When and how to prune?

Pruning plays an essential role in fruiting of kiwifruit. Kiwis are borne on shoots of the year; pruning encourages fruiting. It is also a voluble plant that can quickly become invasive. Pruning is therefore necessary to encourage branching and control its development. Two prunings are recommended:

• Winter pruning

In first years, during winter, from December to mid-February, simply remove obstructive branches and shorten secondary branches before resumption of growth.

Immediately after harvest, each year in October–December, cut back one quarter of branches that bore fruit: leave 2-3 eyes after last harvested fruit cluster.

Shorten other shoots leaving 3-4 eyes.

Keep some main branches that will form the framework.

• Summer fruiting prunings

– In July, when fruits are only slightly larger than a cherry:

Remove undersized fruits so only 4 fruits remain per cluster.

Pinch new shoots at 4 leaves after the last fruit.

Remove suckers to increase fruit size.

– In August: re-prune branches pruned in July, leaving only 2 leaves on the regrowth.

• Maintenance pruning

1. Every 3 or 4 years, cut weakened shoots to 3 cm from main branch
2. On mature specimens, after 10 years of cultivation, cut old wood at base above a shoot
3. On male plants, simply shorten length of shoots

→ Find all our tips: “Pruning kiwi: when and how to prune Actinidia?” and “how to train kiwi“.

Actinidia arguta in autumn

When and how to harvest kiwifruit and kiwi berries?

Once your kiwifruit are planted, remember that you will need to wait around 4 to 5 years before you can harvest fruit for the first time.

Depending on variety, harvest of kiwifruit takes place between September and December, up until the first frosts. Pick them in dry weather. You can pick them while still green because they continue to ripen after harvest. Harvest of Kiwai takes place from late September through October.

A young kiwi plant will produce about 10 kg, then up to 30 to 50 kg of fruit per year after 10 to 12 years of cultivation.

How to store kiwifruit?

These “plant mice” will only keep for a few days at room temperature or in the fridge for around fifteen days after harvest. They can also be stored for several months at 2 to 5 °C in a ventilated, dry cellar or larder, or can be frozen.
If you want to speed up ripening, place kiwifruit near apples or bananas.

Benefits and Uses of Kiwifruit

Low in calories (47 kcal per 100 g), kiwi is eaten fresh, with a spoon when simply halved or peeled. Good for health, this fruit is packed with vitamins, notably C (more than oranges!) and E. It is also rich in fibre and trace elements. Its black seeds contain omega-3 fatty acids. Kiwaï is sweeter than common kiwi and is also higher in calcium and vitamin C.

It is a fruit with antioxidant properties, protective against cardiovascular diseases.

Once peeled, the tangy, sweet flesh enhances the flavour of desserts such as fresh fruit salads and lends itself to making jams, compotes, tarts and sweet-and-savoury dishes.

Possible diseases and pests

When grown in good conditions, Actinidia is hardy and not very susceptible to disease or pests. Rarely ill, it can nevertheless be susceptible to bacterial necrosis (Pseudomonas syringae and P. viridiflava) if soil is too wet: ensure good soil drainage, avoid wetting the foliage, remove affected parts, make clean, neat pruning cuts, and apply horsetail decoctions.

If soil is too lime-rich, chlorosis may appear, causing foliage to yellow.

Red spider mites also cause leaves to yellow, then dry out and fall. They favour warm, dry conditions: don’t hesitate to mist the foliage to get rid of them.

→ Find out more about kiwi diseases and pests in our advice sheet!

Multiplication

Kiwi multiplication is done either by propagation by cuttings or by layering. Grafting is very reliable but a technique mainly for professionals.

Propagation by cuttings

Propagate kiwi by taking semi-woody cuttings in summer.

• Take a semi-woody shoot about 15 centimetres long from the tip of current-year shoots
• Remove leaves from the base of the stem, leaving only two at the tip
• Plant the cutting in a mix of turf and sand
• Place the cutting in a covered, warm spot at 25 °C, maintaining a humid atmosphere throughout winter
• Plant the rooted cutting the following spring

Discover more advice with How to propagate a kiwi? Our tips for success and Propagate your plants successfully

By layering

Its branches are very long, which makes layering easy!

• In spring, bend a flexible branch into soil at the base of the plant
• Remove leaves and scrape the bark over 5–10 cm on that section of the stem
• Bury it in a furrow 10–15 cm deep, close to the mother plant so it can root
• Cover with potting compost and secure the layer
• Lift the tip of the branch and stake it
• When the layer has sufficient roots you can cut it just below to separate it from the mother plant, then replant it in open ground

Companion planting for kiwi

The Kiwi can be planted in orchard or ornamental garden. It should be trained as an espalier. It adapts perfectly to pergolas, trellises, dresses walls or will naturally twine around trees. Cis both a fruit-bearing and ornamental tree, thanks to its lush foliage and fruits hanging well into winter.

An espalier-trained Actinidia on a structure

It pairs well with Schisandra Chinensis, another fruit-bearing and decorative liana that, like it, prefers moist soils and a sunny to semi-shaded aspect, or with Goji (Lycium barbarum). To create a bountiful trellis through the seasons, include it with honeyberry bushes or May berries.

In orchard, plant it near an Asimina triloba or “Paw Paw”, a small fruit tree with tropical looks, or near an arbutus or “Strawberry Tree” with round fruits resembling strawberries.

Perennial groundcovers such as creeping bugles and heucheras will keep its roots cool all summer.