Kiwiberries are the fruit of the hardy kiwi vine (Actinidia aruguta) and super hardy kiwi vine (Actinidia kolomikta), smaller cousins of the familiar fuzzy kiwifruit (Actinidia deliciosa). Kiwiberries are generally the size of large grapes and can be popped in the mouth whole. I can only describe them as a tropical explosion- both sweeter and more flavorful than their fuzzy cousins. The kiwiberry also has high levels of anti-oxidents, Vitamin C, Vitamin A, and Potassium. This delightful fruit is still relatively unknown, although PA’s own Kiwi Korners farm is now supplying Whole Foods, Trader Joe’s, and Philadelphia’s Fair Food Stand in season.
Hardy kiwi vines are relatively easy to grow and well adapted to Philadelphia’s climate. In fact, they will take cold up to zone 4 (or 3 in the case of the super-hardy: hello Siberia!). Hardy kiwis are very vigorous vines once they get going, so make sure to plant them where you have an adequately large structure for them to grow on. They can be a little finicky when young, so either start with larger plants or pay them particular attention in the first couple years, including some protection from late winter sun. Hardy kiwi vines grow well in partial shade but produce best in full sun. They tolerate a good range of soils as long as there is good drainage. For best growth and production, the vines do appreciate regular and thorough watering and benefit from the annual application of a nitrogen source like compost or soybean meal. Because of their vigorous nature, pruning to keep them in bounds may be labor intensive.
Commercially, hardy kiwis are usually grown on a 6′ high T-bar trellis system with a single trunk and two permanent cordons (branches). Apparently some farms in New Zealand grow them on pergolas and this can be a beautiful and productive choice for the edible landscape. I have also seen them growing happily and productively on chainlink fences with little apparent care. In their natural habitat, the vines climb large trees (up to 60 feet) in the forests of China. A tree you don’t particularly care for can be used as a living trellis, although a large ‘kiwiberry tree’ of this kind can be difficult to harvest.
Hardy kiwi vines do require a male pollinator, at least one for every eight females. As wind is the primary pollinator, plant the male to the west or the direction of the prevailing wind. Different cultivars bloom at different times, so it is also necessary to make sure the male and female bloom times overlap. According to David Jackson of Kiwi Korners, this can be difficult as catalogs and suppliers are not always reliable in their delivery of specific genders and varieties. They also report that the supposedly self-fertile ‘Issai’ variety has been less than impressive in their trials.
Hardy kiwis are harvested in the fall when they begin to soften and sweeten. It may take up to eight years before hardy kiwis begin production, although with proper siting and pruning it can take as little as three. Once started, hardy kiwis can be quite prolific, producing up to 100 pounds of fruit from a single plant.
Although the larger size and more consistent production of the hardy kiwi makes it superior for commercial production, the super hardy kiwi may be a better choice for the backyard grower. The vine is less vigorous, thus easier to maintain in smaller spaces; more shade tolerant (always a bonus in the city); and more ornamental, featuring striking pink and white variegated foliage. The super hardy kiwi is also known as the ‘Arctic Beauty’ or ‘Kolomikta’ kiwi.
For more information on growing kiwiberries, I’d recommend Lee Reich’s Uncommon Fruits for Every Garden. Plants can be sourced from Rain Tree Nursery, Useful Plants Nursery, Edible Landscaping Nursery, or Tripplebrook Farm. I’ve even seen them at Lowe’s in recent years although I wouldn’t go so far as to recommend that as a source.