Actinidia arguta 'Jumbo'
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Actinidia arguta 'Jumbo' |
October is the month when fruit of most of the varieties of actinidia ripen. Though still little known in colder climatic zones, these deciduous climbers are very valuable garden plants that, besides adding ornament to the garden with its winding stems, yield tasty fruit. Actinidias are comparatively undemanding, easy to grow, disease and pest resistant, and well able to tolerate urban conditions.
The plants from the genus Actinidia are native to the countries of Far East, from Manchuria to Java. Their fruit is a berry, just as a tomato or a gooseberry, and, in the case of most species, it's edible. Usually the plant is dioecious, that is individual flowers are either male or female, but only one sex is to be found on any one plant. The most acknowledged is the Kiwi fruit (Actinidia deliciosa) native to the Yangtze River valley in middle China. At the beginning of the 20th century it was brought to New Zealand, where its name was changed from Chinese gooseberry (which seemed to put off some people) to Kiwi after the supposed resemblance of the fruit to the national bird, the flightless Kiwi. Nowadays Actinidia deliciosa is widely cultivated for its edible fruit in warm temperate zones of Italy, Spain, Greece, France, New Zealand, the USA, Japan Israel and Chile. Unfortunately the varieties of Kiwi fruit are frost tender and are killed back at about –10oC. The most frost hardy cultivar of the species – a hermaphrodite form 'Jenny' is hardy down to –15oC, but the fruit it yields is small and insipid.
 Actinidia arguta 'Weiki' - female flowers |
 Actinidia arguta 'Weiki' - male flowers |
The species of Actinidia arguta (Tara vine) and Actinidia kolomikta are much more frost-resistant than Actinidia deliciosa, and therefore may be cultivated in our climate. Actinidia arguta, depending on a variety, can sustain temperatures from -23oC down to -35oC, and Actinidia kolomikta
 Actinidia kolomikta 'Adam' |
In fruit gardens and orchards Actinidia arguta is being seen as having the biggest potential with its comparatively large, tasty berries. In order to produce fruit the species needs a long growing season – around 150 frost- free days. An adult plant can yield between 10-20kg of berries. This rampant climbing plant can grow up to 30-50m in its homeland, while in colder climate, in Poland for instance, it reaches up to 4-8m. Young shoots are brown, turning to pale gray with age. Large ovate green leaves change color to yellow in autumn and then fall off. The following varieties of Tara vine are available in Poland:
 Actinidia arguta 'Geneva' - picking fruit |
 Actinidia arguta 'Jumbo' - berries |
 Actinidia arguta 'Ken's Red' - picking fruit |
 Actinidia arguta 'Weiki' - berries |
Actinidia kolomikta requires around 130 days without ground frosts in order to yield fruit. Berries ripen in August and fall immediately, which may be an obstacle for its widespread use in commercial plantations.
 Actinidia kolomikta 'Adam' - leaves |
 Actinidia kolomikta 'Sientiabrskaja' - fruits |
Actinidia is best propagated from stem cuttings taken in midsummer, or by layering. It should be grown in a container for 1-2 years to ensure good rooting before planting it out into its permanent position in a garden
Cultivation
If you choose a dioecious
variety, you will have to plant both the male and the female form at close
proximity (3-5m at best). When planting a larger number of actinidia it's
enough to plant one male form for every 5-8 female plants. The males should be
evenly distributed among the females and come into flower at
 Actinidia arguta 'Weiki' |
Male flowers, borne in racemes of more than a dozen, have well developed stamens with pollen which remains fertile for 3-4 days, while female flowers are borne individually or in clusters of two or three, and consist of a large, well-developed pistil surrounded by barren stamens. They can be pollinated for 9-10 days. It's vital that both female and male flowers bloom at the same time. They are essentially pollinated by bees and other insect and, to a lesser extent, wind. Unfortunately actinidia flowers are relatively unattractive for insects, so they have to be in profusion to ensure good pollination. In the absence of insects you may also try hand-pollination. Pick a freshly opened male flower and brush it for 1-2 seconds against a female flower. The pollen of one male flower is sufficient to pollinate about 5 female flowers.
Actinidias in general, and more sensitive species and varieties in particular, prefer warm, wind-sheltered positions. You should avoid frost hollows as the genus is subject to damage by late frosts, especially in spring. When planning where to plant your actinidia, it may be worthwhile to remember that large lakes and rivers are natural reservoirs of heat. Likewise, the insulated walls of the houses give off some heat and thus increase the chances of winter survival of these tender plants. West and southwest positions, shaded till mid-morning, prove to be the best for the purpose. Actinidias are the most vulnerable during the first 3-4 years after planting, so in that period you should pay particular attention to providing appropriate protection against cold, such as e.g. putting mulch around the base of the plant. I wouldn't recommend cultivation in polyethylene tunnels as such plants start their vegetation period earlier what makes them more subject to late season frosts.
Actinidias grow well in various soils, though prefer soils that are rich in organic matter, and light, with thickness not less than 1-1,5 m. It should be well drained and moist, but not waterlogged, and somewhat acid (pH 5-6.5). As actinidias are shallow rooted plants, you should avoid loosening the soil lest you damage the roots. When planting out, the plants should be put to the ground at the same level they used to grow in a pot, into a hole dressed with compost or well-rotted manure. Actinidias need large volumes of water during the entire growing season and it's especially important to water the plants regularly in the time of intensive growth or in the heat of summer. They also require heavy nitrogen feeding.
 Actinidia arguta trained along a T-shaped trellis |
 Actinidia arguta 'Weiki' - in the garden |
Pruning
When used as an ornamental
plant, actinidia can be left to grow in an unrestrained fashion, with only occasional trimming of unruly
growth. Such a plant, however, will start yielding fruit later and it will be
of poorer quality. If you want to achieve the best crop, you should specially
train your actinidia and prune it hard, bearing in mind that berries are borne
on the shoots that are 2-3 years old.
 Actinidia arguta 'Weiki' trained along a T-shaped trellis |
In commercial plantations actinidia is usually trained along a T-shaped trellis (picture A below), as it ensures the best crop. In amateur cultivation it's best to grow plants along the wires stretched between posts, against a wall or a fence (picture B below). It takes 3-4 years to establish the plant, but once it's done, actinidia will continue to grow and bear fruit even for 50 years.
In the first growing season train a leading shoot. In January – February (do it before the vegetation period starts, otherwise it will bleed) trim it 3-5cm above the top of the supports (picture A2 and B2 below). In the second year choose a pair of the strongest lateral stems and train them to the sides tying them to a wire. In winter prune their tips leaving 8-12 buds on each of them (picture A3 and B3 below). In spring these buds will develop into permanent fruiting stems and will start yielding fruit in the following year. Again they should be trained to the sides and pinched out at the tips in August to encourage them to form numerous flower buds (picture A4 and B4 below). Pick berries in autumn (picture A5 below), and during winter cut back 30% to 70% of fruiting stems (picture AB 6 below), above the branching point from which new fruiting shoots will grow. Every year in summer and winter you should remove all side shoots growing from the trunk, and thin out excessive growth. Pruning helps control spreading and reduces vegetative vigor thus promoting fruit growth and development, permits adequate air movement through the plant and opens up the inside of a shrub to maximize light penetration, all of which is essential for optimal fruit set, flavor, and quality.
 Actinidia pruning schema |
Yielding fruit
Actinidias
usually start bearing fruit in the fourth year after planting. When picked unripe, they
will soften and ripen if kept together with fruit producing ethylene, e.g.
apples. It's best to put them in a cellophane bag and leave for a few days at
room temperature.
Berries are smooth-skinned, so they can be eaten without peeling. They can be eaten raw, added to cakes, jellies, salads and other dishes enriching summer and autumn meals, dried as grapes (they will resemble raisins), frozen and marinated. They are perfect for preparing wines, jams or marmalades.
 Actinidia arguta fruits. Varieties from the left: 'Geneva', 'Weiki', 'Ken's Red', 'Jumbo' |
Actinidia fruit is very healthy. Being almost totally devoid of fat, low in sodium and rich in vitamins (E and C), potassium and other microelements e.g. zinc it is a perfect supplement to a wholesome diet. The fruit of Actinidia arguta contains about 400 mg% of vitamin C, which is up to 4 times the vitamin C content of a lemon or an orange.
Planting Tara vine in allotments, garden plots, or even on a bigger scale, in production plantations has gained popularity in Japan, the USA, Germany, Switzerland and many other European countries, and is becoming more and more popular in Poland. I personally believe that actinidias are well worth widespread use.