Viticulture is the science of growing grapes. In New Zealand, grapes are mainly grown for wine production. Some are also grown as table grapes.
For much of the 20th century, grape growing was confined to the warm northern half of the North Island. Although 19th-century settlers had managed to grow wine grapes in a number of regions, and an early viticultural expert identified suitable areas in the southern North Island and South Island, few grapes were grown south of Hawke’s Bay until the 1970s.
The government ran a viticultural research station at Te Kauwhata, in the Waikato, from 1901 until the 1980s.
As recently as the 1960s, government viticulturalists advised that the South Island was unsuitable for growing wine grapes. In the 1970s and 1980s, some people chose to ignore this advice. They planted the right grape varieties for their sites, and went on to produce award-winning wines.
Grape plants are woody climbing vines belonging to the genus Vitis. Their stems can reach 35 metres in length, but in cultivation are pruned back to 1–3 metres. They produce clinging tendrils that allow the growing stems to attach themselves to upright supports.
Each of the thousands of varieties of grape has a distinctive leaf, which is hand-sized, circular or oval, and usually lobed. The flowers are tiny, green and arranged in bunches. They are self-fertilising and wind-pollinated. The fruit is a spherical, pulpy berry containing two to three seeds, and is yellow-green, blue-black or reddish-purple when ripe.
Annual growth cycle
Grapevines are deciduous. As the weather cools and the days shorten in autumn (March–May), their green leaves turn yellow and crimson, then drop off. The leafless stems, known as canes, then enter a period of dormancy over winter, which is the time for pruning.
When spring (September–November) arrives and average temperatures reach 10°C, buds swell then burst, and leafy shoots appear on the canes, followed by flower clusters. Shoots grow rapidly during summer, and fruit develops and starts to ripen. Fruit is harvested from late February for early-ripening varieties, through to mid-May for late-ripening grapes.