Although the hairy Actinidia deliciosa is the kiwi commonly found in grocery stores, there are several types of kiwi. Hardy kiwifruit (Actinidia arguta) is a small, green fruit with smooth skin, while its cousin the golden kiwi (A. chinensis) is sweeter, rounder and bronze-colored.

Of the three types, hardy kiwi fruit plants tolerate cold temperatures best--as low as -25°F--although they are sensitive to late spring frosts. In the U.S., A. deliciosa is grown primarily in California, although most of the supermarket fruit comes from New Zealand. It can grow in hardiness zones 7-9; the New York City area is on the edge of this range. A cold snap can damage vines. The golden kiwi requires warmer weather, thriving in zones 8-10.

A strong-growing perennial vine with small leaves and bright red stems, the hardy kiwi can grow to 40 feet in length. If not pruned and trained, the vines will grow up trees and over fences. Once established, plants can live for fifty or more years. In early summer, the vines bear small white flowers with chocolate-colored centers on the previous season's spur growth. They have a fragrance similar to lily-of-the-valley and are pollinated by wind or insects. Greenish-yellow fruits develop in summer and into the fall, and ripen very late in the season.

Hardy kiwi is often grown as an ornamental vine. Most hardy kiwi plants are dioecious; that is they bear either male or female flowers, but not both. For this reason, you need to plant both a male and female plant if you want to harvest fruit. (Some nurseries sell hermaphroditic plants which bear flowers of both sexes, but their performance has been poor.) To ensure pollination and fruit set, purchase at least one male plant for every nine female plants. Avoid planting in frost pockets. Sites with northern exposure are good because they delay early growth in spring, which can be damaged by late frosts. Construct a trellis system or otherwise support vines. Prune plants at least two or three times during the growing season and once during winter.

Kiwifruit can be propagated from cuttings or seeds. To grow plants from seed, remove the seeds from a mature fruit and let them dry for two days. Refrigerate them in moist perlite at 40°F for 4 months. Then plant the seeds no deeper than 1/8 inch in a sterile potting mix and cover the container to keep the humidity high. The soil should be moist but not wet. As soon as the plants germinate, uncover the container. After the seedlings are up, put a thin layer of clean sand on top of the medium. When plants have four true leaves, transplant them to individual pots. At this time, use a liquid fertilizer. Transplant the seedlings to where they will grow when they are several inches tall.

Kiwifruit will not reach maturity and flower until about their fifth year. Fruit matures in October, which may be after the date of the first frost. For this reason it is difficult to harvest vine-ripened fruit. Fruits will ripen in the refrigerator, but their storage life is much shorter than that of the commercially available kiwifruit. Flavor is sweeter, however, in the fuzzless hardy kiwifruit.

Several hardy kiwi cultivars are available through retail nurseries. Improved selections that perform well in New York include 'Ananasnaja', 'Geneva', 'Meader', 'MSU', and the 74 series.

For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service