The kiwi fruit, despite the shared name with the flightless avian mascot of New Zealand, is a Chinese native vine formerly known as the Chinese gooseberry. The kiwi is a member of an unusual group in the plant world in that its male and female flowers are on separate plants; to ensure successful pollination and fruiting, one male plant should be planted for every six to eight female plants.
Kiwi Plant Varieties
Gardeners in warmer climates may grow the grocery-store-variety kiwi, Actinidia deliciosa, which is hardy to Zone 7. Growers in northern latitudes should use one of two hardier varieties readily available on the market: the aptly-named hardy kiwi (A. arguta) or Arctic kiwi (A. kolomikta). Hardy kiwi produces grape-sized fruits with the same flavor and texture of larger kiwi fruits and is hardy to Zone 4. Arctic kiwi is hardy to Zone 3 and also produces smallish edible fruits, but is frequently grown for its showy pink, white and green variegated foliage.
Kiwi Plant Characteristics
Both male and female strains of the kiwi plant are woody perennial vines. Hardy kiwi can grow to 15 feet or longer, and Arctic kiwi can reach sizes of 25 to 30 feet. Female plants typically do not bear fruit for the first several years of growth, after which the plant may bear heavily for several decades---Oklahoma State University's description of Arctic kiwi indicates that healthy vines may produce fruit for 60 years or more. Though both types of kiwi are rated as hardy plants, a spring freeze after buds or flowers have appeared will usually kill the new growth and prevent fruit production for that year.
Female Kiwi Plants
At a glance, the flowers of the male and female kiwi plants look virtually identical. Though the female flower has a dense ring of anthers---structures that in other flowering plants function as male pollen producers---the pollen of the female kiwi flower is sterile. The center of the flower is dominated by a thick white mound, which develops into the kiwi fruit after pollination. The flower can have either five or six petals, with new flowers being a creamy white color and aging into a light yellow.
Male Kiwi Plants
Like the flowers on a female plant, male kiwi flowers start out as a white, five- or six-petaled flower that turns yellow with age. The main differences are that the center of the flower lacks the marble-shaped ovary mound and that the circle of anthers is less densely packed than on a female flower. Each anther is topped by a bright yellow puff of pollen, which must be carried by insects to female flowers in order for pollination to occur.
Kiwi vines grow best in rich, well-drained soils. Vines should be situated in mostly sunny locations but have some protection from strong winds. Kiwi vines require a sturdy trellis to climb; left untouched, the vines will sprawl over the ground with a loose and wandering habit. In colder climates, Arctic kiwi will die back to the ground but regrow each year; hardy kiwi can be pruned in winter to encourage denser foliage or fruit production.