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

Description and botany

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

Kiwi is native to temperate regions of China, not New Zealand, although New Zealand remains its main exporter. Kiwi arrived in France, in Nice, in 1904 and has since acclimatised widely, mainly in Landes, the Midi and Corsica.

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

This vigorous, woody, rambling liana bush clings to any support thanks to its tendrils. Its long sinuous, twining stems can grow 3 m per year, reaching 6 m in height, sometimes more in favourable conditions, and 4 m spread at maturity. Young shoots with reddish bark are covered in reddish down. Kiwi is long-lived and can live 50 to 100 years.

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

Several foliage types: Actinidia deliciosa and Actinidia kolomikta (ornamental kiwi)

On this ample foliage, in May–June, after only fourth or fifth year of cultivation, small flowers open singly or in groups of three in the axils of leaves on last year’s shoots. These scented flowers have five petals, cream-white to yellowish-white depending on variety. But how to recognise a male and female kiwi plant?

Most Actinidia species are dioecious, meaning a male plant must be nearby to allow pollination by bees. However, new Actinidia varieties are often self-fertile (male and female flowers on same plant): a single plant is enough to set fruit. Sex is easily recognised by looking at flowers: female flowers are 3–4 cm in diameter, solitary and have short stamens surrounding white stigma, whereas male flowers are smaller, grouped in cymes of three and bear numerous fertile stamens, very prominent, golden and powdery.

Only female plants produce fruit. Flowering is followed by formation of abundant, tasty, ovoid summer berries 3–9 cm long: the kiwifruits. Appearance, colour, size and flesh vary by species and variety.

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

Flowers and fruits of kiwi plant

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 flavour is closer to gooseberry and is sweeter than traditional kiwi.

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

Name “Kiwi” refers to bird endemic to New Zealand, whose plumage is reminiscent of the fruit’s skin.

Self-fertile or dioecious species?

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

Main species and varieties

Duos

Our self-fertile varieties

Other interesting species

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

'Issai' variety, producing small green fruits, is self-fertile and will act as pollinator for '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 kiwifruit close together will yield 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

This variety is the only self-fertile Kiwi arguta. This kiwifruit is eaten unpeeled thanks to its smooth skin. Its flesh is sweeter and richer in vitamins than that of common kiwifruit.

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

See the product sheet

Kiwi Plant Solissimo (self-fertile) - Actinidia chinensis

A single young plant is enough to obtain an abundant harvest. This variety is very productive!

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

See the product sheet

Kiwi Plant Jenny (self-fertile) - Actinidia deliciosa

A fine self-fertile variety, producing small fruits with green flesh. To train along a pergola, trellis or arbour.

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

See the product sheet

Yellow Kiwi Plant Minkigold (female) - Actinidia chinensis

A variety producing golden kiwifruit with yellow flesh and a slight apple fragrance. This female young plant requires proximity of a male young 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

It's the tastiest of kiwifruit! It produces golden kiwifruit with particularly sweet yellow-golden flesh. It needs the Kiwi Golden Delight (male) to fruit.

• Flowering time July
• Height at maturity 5 m

See the product sheet

Yellow Kiwi Plant Kiwi Wonder (female) - Actinidia deliciosa

An unusual variety with thin, hairless skin producing yellow fruits with yellow flesh and a red centre, very sweet and non-acidic. It requires proximity of a male young plant to 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

This non-self-fertile variety produces red kiwiberries with slightly purplish flesh that can be eaten with the skin. It's a female young plant requiring a nearby male young 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. It is however sensitive to severe late frosts, since buds are killed at -4 to -5 °C. Give it a spot sheltered from cold winds and spring frosts that can scorch young shoots and damage flowers. Avoid in particular walls exposed to north or east.

Kiwi prefers sunny but not scorching situations, especially in southern regions. It likes rich, deep soils with not too much lime, which can cause chlorosis, that are well-drained and remain cool at depth. It dislikes waterlogged, oxygen-poor soils that retain water in winter. It will naturally find a place on a raised bank if your ground holds too much water in winter.

Kiwi needs space to establish, and for non-self-fertile species two plants (a young female plant and its pollinator) are necessarily required for fruiting.

Trellising of kiwi is necessary: provide a sturdy support about 5 to 6 m long and 3 m high so its stems can cling.

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

When to plant?

Plant kiwi ideally in autumn, from October to November. It is preferable to plant in spring in regions with severe winters. In temperate zones, our container-grown plants can be planted all year round outside periods of frost.

How to plant?

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

Planting:

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

Kiwi trained on wire mesh

Maintenance, pruning and care

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

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

Carry out shallow hoeing to keep the plant base clean and prevent germination of adventive weeds.

Train the liana as it grows.

Pruning kiwi and kiwaï:

When and how to prune?

Pruning plays an essential role in fruiting of the kiwi. 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 types of pruning are recommended:

• Winter pruning

During the first years, in winter, from December to mid-February, limit yourself to removing obstructive shoots and shorten secondary branches before vegetation restarts.

Just after harvest, each year in October–December, cut back by a quarter the branches that bore fruit: leave 2–3 buds after the last group of fruits picked.

Shorten other shoots leaving 3–4 buds.

Keep some main branches that will form the framework.

• Summer fruiting prunings

-In July, when fruits are barely larger than a cherry:

Remove undersized fruits to keep only 4 fruits per cluster.

Pinch new shoots at 4 leaves after the last fruit.

Remove vigorous shoots to increase fruit size.

-In August: retrim branches pruned in July leaving only 2 leaves on the new growth.

• Maintenance pruning

1. Every 3 or 4 years, cut to 3 cm from the main branch the shoots that have lost vigour
2. On mature specimens, after 10 years of cultivation, cut old wood back to its base above a shoot
3. On male plants, simply shorten the length of the shoots

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

Actinidia arguta in autumn

When and how to harvest kiwis and kiwiberries?

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

Depending on variety, harvest of kiwis 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 Kiwaï takes place from late September through October.

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

How to store kiwis?

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

Benefits and uses of kiwi

Low in calories (47 kcal per 100 g), kiwi is eaten fresh, with a spoon straight from a halved fruit or peeled. Good for your 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. Kiwiberry is sweeter than regular kiwi and also richer in calcium and vitamin C.

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

Once peeled, 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

Cultivated in good conditions, Actinidia is hardy and not very susceptible to diseases and parasitic pests. Rarely diseased, it can nonetheless be vulnerable to bacterial necrosis (pseudomonas syringae and viridiflava) if the soil is too wet: ensure good soil drainage, avoid wetting the foliage, remove affected parts, make clean, neat pruning cuts, and use horsetail decoctions.

If the soil is too calcareous, chlorosis may occur, causing the foliage to yellow.

Red spider mites also cause yellowing of leaves, then their drying out and dropping off. They prefer warm, dry conditions: don’t hesitate to mist the foliage to eliminate them.

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

Multiplication

Kiwi propagation is achieved either by propagation by cuttings or by layering. Grafting is very reliable but mainly intended for professionals.

Propagation by cuttings

Multiply kiwi by propagation by cuttings of semi-woody shoots in summer.

• Take a semi-woody branch about 15 centimetres long from tip of current-year shoots
• Remove leaves from base of stem, leaving only two at tip
• Plant cutting in a mixture of turf and sand
• Place cutting in enclosed, warm environment at 25 °C, maintaining humid atmosphere throughout winter
• Plant 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 base of plant
• Remove leaves and scrape bark over 5–10 cm on that part of stem
• Bury it in a furrow 10–15 cm deep, close to mother plant so it can root
• Cover with potting compost and secure layered branch
• Lift end of branch and stake it
• When layered branch has sufficient roots you can cut it just below to separate from mother plant, then plant out in open ground

Companion plants for kiwi

The Kiwi is planted in orchards as well as ornamental gardens. It should be trained as an espalier. It adapts perfectly to pergolas and trellises, can clad walls or will naturally twine around trees. It‘s both fruit-bearing and ornamental, thanks to its lush foliage and fruit hanging right through to the onset of winter.

An Actinidia trained as an espalier on a structure

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

In an orchard, plant it close to an Asimina triloba or ‘Paw Paw’, a small fruit tree with tropical appearance, or to an Arbutus, the ‘strawberry tree’, with round, strawberry-like fruits.

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