Kiwi

Family

Actinidiaceae

Habit

Climber

Height

9.5 m

Spread

2 m

Growth

medium

Lifespan

50 years

First yield

after 5 years

Yield per plant

up to 90 kg a year

Yield in cultivation

up to 40 t/ha

Energy yield

400 kcal per m² a year

Hardiness

zone 7–11

Shade tolerance

partial shade

Soil

Sand, Silt, Loam

Soil moisture

semi-dry – very wet

pH

5 – 6

Synonyms

Actinidia chinensis

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Edible: The fruit is a 5 to 8 cm long, brown-hairy berry with green, radially patterned flesh and numerous tiny black seeds. It is eaten raw, scooped or peeled, and suits fruit salads, cake toppings, chutneys and preserves. Notable is the very high vitamin C content of around 45 to 90 mg per 100 g, alongside potassium, dietary fibre and folate. Harvest hard and unripe shortly before the first hard frosts; the fruit ripens within a few days at 15 to 20 degrees, distinctly faster next to apples because of their ethylene. Stored cool and dark at 0 to 2 degrees it keeps for several months. Raw kiwi will not let gelatine set and turns dairy products bitter within a short time, because the enzyme actinidin breaks down the proteins; brief heating destroys it. The fruit also contains oxalates, which can irritate sensitive mucous membranes.

Other uses: The kiwi fruits on one-year wood arising from two-year canes and on short fruiting spurs on older wood - the whole pruning system follows from this. The canes are used as living green for pergolas and covered walks, because the large rounded leaves cast dense shade and the plant covers a structure quickly. Fresh flesh contains the protein-splitting enzyme actinidin; it makes the fruit a natural meat tenderiser but conversely prevents gelatine from setting with raw kiwi and turns dairy products bitter. Yellow-fruited species and cultivars contain less actinidin and are therefore better suited to yoghurt and quark. The shoots and roots contain compounds that affect cats much as valerian or catmint does, which is why young plants may be chewed and rubbed to pieces.

Site: The kiwi is a vigorous liana reaching 6 to 10 m of cane depending on cultivar and needs a permanent load-bearing structure - a pergola, espalier or steel or hardwood T-bar, not a garden-centre trellis. It wants a fully sunny and strictly sheltered position, because the large leaves tear in wind and young shoots snap off; a south wall with an overhang is ideal. The soil must be humus-rich, evenly moist and slightly acidic; above pH 7 chlorosis sets in and chalky soils are out of the question. The key planning point is dioecy: every fruiting cultivar needs a male pollinator within about 10 m, usually 'Matua' or 'Tomuri' for 'Hayward'. Only 'Jenny' and 'Solo' crop without a partner, and then less heavily. Cats like to dig at and rub against young Actinidia plants and can destroy them. Care: Water demand is high; the shallow-rooting plant needs regular watering in dry spells and a permanent mulch layer, yet will not tolerate waterlogging. Feed with an emphasis on nitrogen in spring and never after July, so the wood ripens. Established plants tolerate about -15 to -18 degrees when dormant, but young growth is killed by even light late frost - in frost-prone sites a fleece over the framework pays off. Prune twice: in winter cut spent fruiting canes back to two or three buds beyond the last fruit, and in summer shorten overlong shoots. Without pruning the plant goes bare inside and fruits only at the perimeter. First fruit comes after four to five years. Harvest still hard before the first hard frost; the fruit ripens in store.

Kiwi is propagated by cuttings and grafting, because seed-raised plants take years to reveal whether they are male or female. Softwood cuttings are taken in June and July from half-ripe shoots with two or three buds, the leaves halved, and rooted under film or mist at around 20 to 25 degrees bottom heat; rooting takes four to six weeks. Hardwood cuttings from the winter prunings root considerably less well. Cultivars are whip-grafted onto seedling rootstocks in winter or budded in August. Seed raising is worthwhile only for rootstocks: seed from fully ripe fruit is washed out, dried and needs about three months of moist cold stratification at 2 to 5 degrees, after which it germinates at roughly 10 to 20 degrees. Seedlings flower only after four to seven years, so the sex ratio shows up that late.

The kiwi is a neophyte from central China with no ties to native insects, and it plays no role as a caterpillar host. Its large creamy-white flowers in May and June are above all a source of pollen, and pollinators visit them chiefly for that. in Central Europe five bumblebee species are regularly recorded at the flowers, among them buff-tailed, red-tailed, early and tree bumblebee; commercial growers secure pollination with honeybee colonies or mechanically, since wind also carries part of the pollen. For birds the plant offers little, though ripe or split fruit is taken, as it is by wasps. Its real contribution in the garden is structural: the dense tangle of an established pergola gives birds cover and nesting opportunities.

Special features: Dioecious - a male pollinator ('Matua', 'Tomuri') needed per fruiting cultivar, only 'Jenny'+'Solo' self-fertile; needs a permanent load-bearing structure, 6-10 m of cane; lime-sensitive, chlorosis above pH 7; large leaves vulnerable to wind; first crop after 4-5 years; harvest hard, ripens in store; actinidin prevents setting with gelatine; cats destroy young plants; young growth lost to even light late frost;

East Asia: central China. The natural range of the species lies in the Yangtze catchment, above all in the provinces of Hubei, Sichuan, Shaanxi and Hunan. Only in 1904 did the New Zealand teacher Mary Isabel Fraser bring seed to New Zealand, where the first selections were raised; commercial export to England began from there in 1952, and in 1959 the fruit was given the trade name kiwi in London. Today it is grown worldwide in regions with mild winters. China is by far the largest producer with around 64 per cent of the 2024 world crop, followed by New Zealand, Italy, Chile, Greece and Turkey.

In its homeland the kiwi grows as a vigorous woody liana in the deciduous mountain and ravine forests of central China, mostly between 500 and 1800 m. It climbs through trees and shrubs into the canopy but roots in the moist, humus-rich, slightly acidic forest floor in partial shade. The climate is humid subtropical with high air humidity, mild winters and a long frost-free growing season of six to eight months. Characteristic is the combination of evenly moist soil year-round and shelter from wind provided by the surrounding forest - both explain the demands of the cultivated plant. Genuine wild populations have declined sharply through forest clearance.