The kiwi plant is native to northern and eastern China and cultivation spread to New Zealand, where it became a popular landscape and commercial plant. The kiwifruit is grown in warm climates, and a related species, the hardy kiwi, is acclimated to colder regions of the United States. This plant is a prolific vine that can quickly cover an area. It needs the support of a sturdy fence or trellis and regular pruning.
Kiwi plants prefer a sunny location but tolerate partial shade. Their vines need support and protection from strong winds. These plants prefer well-drained, acid soil, with a pH between 5 and 6.5. Supplement the soil with organic compost.
Kiwi vines need plenty of water during the growing season. During the hottest parts of the summer, the vines need even more water. Leaves on plants that do not receive enough water will begin to droop; continued drought will result in browning of the leaves and loss of leaves. Eventually the plant will die without enough water.
Kiwi plants require fertilization with a high-nitrogen fertilizer during the first part of the growing season, from early march through early summer. Later applications benefit the plant but result in fruit that does not store well.
Kiwi plants are either male or female, requiring both plants to produce fruit. One male plant is sufficient to pollinate nine female plants when properly pruned. Occasionally, a fruiting male will appear, but the fruit are substandard.
Kiwifruit and hardy kiwi are trained onto a trellis system for best results. During the first year after planting, the main trunk of the vine is cultivated onto the trellis and all other shoots are removed. The second year, lateral branches are developed, growing up to 10 feet in either direction down the trellis. Fruiting branches should be allowed to grow during the third year. They are spaced about 12 to 18 inches apart down the lateral branches.
Pruning needs to be continuous during the first two years. Once the vine is established, plants are pruned during the dormant period to remove extra fruiting shoots and older wood. Fruiting branches produce for two to three years and are then pruned away in favor of new fruiting shoots.
Kiwis are prolific producers and will overburden the plant if extra fruiting shoots are not removed. Pruning also increases the size of each fruit and benefits the health of the vine.
Male plants are pruned differently. They are ignored during the dormant season so that they will produce as many flowers as possible, then cut back severely after flowering.
The kiwi's fruits are ready to harvest when they have grown to sufficient size and the skin is brown. Smaller fruit can be left to enlarge, and fruit can be harvested several times until a hard frost threatens. The fruit are still hard at harvest and soften after picking.
Kiwi fruit stores well, before ripening, for one to two months under refrigeration at 32 degrees F. Once ripe, the fruit should be used within 10 to 14 days.