|Actinidia arguta subsp. var.||Hardy Kiwi, Kokuwa, Siberian gooseberry, Etc.|
A small, green to purple skinned, fruit similar to kiwifruit, hardy kiwifruit is an edible, berry-sized fruit of a Cultivar Group of the woody vine Actinidia arguta. Often sweeter than the kiwifruit, hardy kiwifruit can be eaten whole and need not be peeled. Thin-walled, its exterior is smooth and leathery, providing a deceiving contrast to the fuzzy, brown exterior of its larger sibling fruits.
Common names include Kiwi Berry, Baby Kiwi, Hardy Kiwi, Dessert Kiwi or Cocktail Kiwi, Bower Vine, Tara Vine, Yang-tao.
Growth Habit: In the forests where it is native, it is a climbing vine (liana), sometimes climbing one hundred feet high into trees. In cultivation it is more well-behaved but must be supported by a trellising system. The plant has a more delicate appearance than regular kiwifruit.
Foliage: Leaves are elongated and generally 2 to 5 inches long and attached to the stem on red petioles. They are usually serrated and far less leathery and fuzzy than regular kiwifruit.
Flowers: The flowers are about one-half inch in diameter, white to cream colored, somewhat fragrant, and produced as singlets to triplets in the leaf axiles. Flowering period extends over several weeks from early May to June, depending on climatic conditions. Plants are dioecious, having male and female flowers on separate plants, thus needing plants of both sexes to produce crops. However, self-fruiting females are known to exist.
Fruit: The fruit are generally green, fuzzless, and the size of grapes. Cut open, they look much like regular kiwifruit with its small black seeds, emerald green color, and typical rayed pattern. Although typically green in both the skin and flesh, some cultivars have various amount of red, either in the skin, flesh or both. Hardy kiwifruits are generally sweeter than regular kiwifruit. Sugar levels vary, ranging from 14% (as with kiwifruit) up to 29%.
Additional differences between cultivars can include perceived aroma of the fruit as well as bitterness of the skin. Commercial cultivation has begun for this crop in many regions of the United States due to the plants ability to grow in harsher climates than the kiwifruit.
|Standard Cyclopedia of Horticulture|
Actinidia arguta, Miq. (A. polygama., Lauche. not Miq. A. volubilis, Carr., not Miq. A. rufa, Miq.). Fig. 115. High-climbing: branches with brown lamellate pith: lvs. broad-elliptic or broadly ovate, 4—5 in. long, cuneate to subcordate at the base, setosely appressea serrate, glabrous beneath except the setose midrib: fls. 3 or more, white. 3/4in. across; sepals elliptic-oblong, tomentulose; petals brownish at the base: fr. subglobose, greenish yellow, about an inch long, sweet. June. Japan, Korea, Manchuria. CH
Only females will fruit.
- Ananasnaja (Anna) - Said to be an outstandingly reliable bearer of relatively large fruit (to 1" X 1-1/2"). Fruit is said to be not quite as sweet as that of some other cultivars. Appears to be more resistant to spring frosts than other Actinidias and will supposedly produce blossoms on re-growth if the original growth is killed by frost in spring. A medium-size fruit, 4cm long and 2½cm in diameter183. Juicy and sweet with a distinct pineapple-like aroma and flavour183. Possibly a hybrid with A. kolomikta, it is a reliable bearer that often produces fruit in bunches like grapes183. A very hardy plant, tolerating temperatures down to -35°c when fully dormant183.
- Ananasnaya(different than above, with a Y)- Fruit is said to have a pleasant pineapple-like flavor. Appears to be a different cultivar from 'Ananasnaja', above. Can bear over 200 lbs. of fruit.
- Dumbarton Oaks - Fruit is said to be especially sweet.
- Geneva - Bears fruit to about 1" long; ripens here in late September and October. From the Geneva, NY Agricultural Experiment Station. Very vigorous and reliably hardy.
- Issai (2 distinct self-fruitful cultivars from Japan) - Bears fruit to about 1" long; ripens here in late September and October. Very vigorous and reliably hardy here. A long fruit, up to 4cm in diameter, it is sweet with a good flavour and high quality183. The fruit is seedless when it is not pollinated183. This cultivar can produce fruits in the absence of a male pollinator, often in the first year after grafting, but yields will be increased if the plant is pollinated183.
- Ken's Red
- Langer - Bears medium-size fruit of fine quality183. The original plant is from a homestead high in the Cascade Mountains where it had to endure summer droughts, deep snow, severe cold and wind, and other adverse conditions183.
- Michigan State - A female selection from Michigan State University. Well regarded for fruit size and quality.
- 119-40B - A self-pollinating selection from the Arnold Arboretum in Massachusetts. Appears to be a typical A. arguta in other respects (unlike 'Issai'), and will probably be useful for pollinating other A. arguta cultivars.
- Red Princess
- Professor Meader selections
- 74 Series
Various males are known but no extensive work has been done to determine pollen count or viability, flowering times, or vigorousness. If available, pollen from the regular kiwifruit works well but the seed resulting is usually sterile.
- 74-46 - A male pollinator for other A. arguta cultivars.
- Meader male - A male pollinator for other A. arguta cultivars. Can also be used to pollinate Actinidia callosa and A. purpurea.
The fast-growing, climbing vine is very hardy (hence the name), and is capable of surviving slow temperature drops to -32°C (-25°F). However they must acclimate to cold slowly and any sudden plunge in temperature may cause trunk splitting and subsequent damage to the vine. The vines need a frost-free growing season of about 150 days which will not be hampered by late winter or early autumn freezes in order to give a good crop, but are not damaged by late freezes. The vines can also be grown in low-chill areas, though all cultivars need a certain period of winter chilling and their needs vary, dependent upon cultivar, however, the exact amounts needed has not yet been established. To date, all cultivars that have been grown in both high chill and low chill areas have produced equally well. Late winter freezing temperatures will kill any exposed buds. The plants can be successfully grown in large containers.
Location: The vines will tolerate some shade but prefer a sunny location where they can ramble across some type of trellising system. They should have some protection from strong winds
Site Preparation: Hardy kiwi plants need a substantial trellis, patio cover, or other permanent place to grow upon. For the trellis system, either a single wire or T-bar system can be installed. Both have a 4 inch by 4 inch redwood post of 8 feet. For the T-bar, a 2 inch by 6 inch crossarm about 4 feet long is bolted in place. Bury the post 2 feet into the ground and cement in if at all possible. At each end of the system, a cemented deadman should be in place. Run wires across the posts and anchor tautly to the deadman. When using a patio cover, no extra trellising needs to be in place. Simply run the plant up a corner post to the top and allow the plant to then form a spoke work of shoots which would resemble an umbrella.
Soils: Hardy kiwi prefer well-drained, somewhat acid (pH 5 - 6.5) soils. Neutral soils are acceptable but the leaves may show nitrogen deficiency when the soils become too basic. The plants will not tolerate salty soils.
Irrigation: Hardy kiwi plants need large volumes of water during the entire growing season but must also be in well-drained soils. Watering regularly in the heat of the summer is a must. Never allow a plant to undergo drought stress. Symptoms of drought stress are drooping leaves, browning of the leaves around the edges, and complete defoliation with regrowth of new shoots when the stress is continuous. More plants probably die from water related problems than any other reason.
Fertilization: Based on work done on the regular kiwifruit, hardy kiwi plants are heavy nitrogen feeders which should be applied in abundance during the first half of the growing season. Late season applications of nitrogen will enhance fruit size but are discouraged as fruit then tends to store poorly. In basic soils, a citrus and avocado tree fertilizer should be broadcast about the vine and watered in well in early March. Follow up the initial fertilizing by supplemental additions to early summer. In other areas, use a high nitrogen fertilizer which contains trace elements unless it is known that the particular soil is deficient in another nutrient. Mulching with manures and/or straws is very beneficial. However, do not put the mulch directly in contact with the vine as crown rot will occur.
Pruning: For best fruit production, pruning in the winter is a must. All pruning techniques are usually based on a "cane replacement" and differ only based on the trellising method used. Kiwi vines need to be supported and this is usually done in one of three ways: single wire, 3-5 wire on a T-bar system, or onto a patio cover. In all cases, one stem is trained up to a wire at six feet and then allowed to grow along the wire. When growth ends in a "pig-tailing" of the shoot, it is cut behind the entanglement and new a shoot allowed to grow from a leaf base. After two years multiple shoots will now emerge from the lateral mainline. During the growing season, each lateral cane will send out a new shoot about 1/3 of the way from its own starting point. The next winter, prune off the older cane at the point that it connects with last summers new shoot. This process repeats itself every year.
Harvest: Ripening depends both on the cultivar grown and local climatic conditions. The Cordifolia cultivar ripens first in early September while the Anna (Ananasnaja) may need to wait until late October/early November before it sweetens to its best. Hardy kiwifruits drop or come off easily when they are ripe. Usually they are picked at the mature-ripe stage and allowed to ripen off of the vine as is done with kiwifruit.
Cuttings for true offspring. Can be grown from seed, but outcome of fruit quality (and sex) is uncertain. In areas where the regular kiwifruit will grow, scions of the hardy kiwi may be grafted directly onto kiwifruit rootstock. Otherwise, one must either root their own from hardwood or greenwood cuttings or buy established plants.
Seed - sow spring in a greenhouse133. It is probably best if the seed is given 3 months stratification113, either sow it in a cold frame as soon as it is ripe in November or as soon as it is received. Fresh seed germinates in 2 - 3 months at 10°c, stored seed can take longer133. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in light shade in the greenhouse for at least their first winter. When the plants are 30cm or more tall, plant them out into their permanent positions in late spring or early summer, after the last expected frostsk. Most seedlings are male126. The seedlings are subject to damping off, so they must be kept well ventilated113. Cuttings of softwood as soon as ready in spring in a framek. Cuttings of half-ripe wood, July/August in a frame. Very high percentage113. Cuttings of ripe wood, October/November in a frame.
Pests and diseases
Plants are relatively free from problems, possibly due to their lack of heavy planting into areas so that pests begin to take a liking to the leaves, trunk, or roots. One odd problem is the fact that the trunks have a catnip-like aroma which cats love to rub against. When plants are small, this can be a problem as they can rub off any new shoots which emerge in the spring. Garden snails can also be a problem on younger plantings. Other pests include deer that browse on the leaves and gophers that attack the roots. Scale insects can damage if populations build up too extensively. Greenhouse thrips may also damage the fruit.
- Reich, Lee. Uncommon Fruits Worthy of Attention. Addison-Wesley, 1991. pp 121-138.
- NZKiwiberry (Information page at Delica exporting company)