Good wine starts in the vineyard. It is the grape grower’s job to deliver a quality crop to the winemaker. The grower must match a grape variety to its site and manage its growth through the seasons.
Through trial and error, and bitter experience, New Zealand growers have learnt they need to plant healthy vines of a suitable variety for their site. Most now plant certified virus-free vines, grafted onto phylloxera-resistant rootstocks.
For years New Zealand growers could not be assured of the identity of grape varieties purchased from nurseries. Varieties look very similar, especially in the dormant stage, when cuttings are sold. Major suppliers now guarantee the identity of their material by DNA analysis or by having it checked by an internationally recognised expert (an ampelographer).
Planting and training vines
Growing vines need some form of support to hold them above the ground and to maximise sunlight on their leaves. In New Zealand, they are trained onto a wire trellis system attached to posts in the ground. There are various ways of arranging shoots and leaves, but most New Zealand growers use the vertical shoot positioning method. Trellis rows are usually oriented north–south so each side of the canopy gets similar amounts of sunshine.
The density of planting varies between vineyards. Rows may be spaced 1.5 to 2.5 metres apart, with plants 0.9 to 2 metres apart.
If grapes are not pruned each year, they develop many unproductive shoots and soon become a tangled mess of leaves and stems. At least 90% of the previous season’s growth is removed each winter. Vines are either spur pruned – where one or two branches are permanently trained along a trellis wire and the side branches are cut back to two or three buds – or cane pruned, where one or two new branches are selected each winter and trained along the wires, and the rest are removed.
The Silver Secateurs contest to find New Zealand’s best grape pruners is run each year alongside the Romeo Bragato viticultural conference. Competitors prune and tie four sauvignon blanc grapevines, and are judged on the quality and speed of their work.
As grapes ripen, their sugar levels increase and acid levels decrease. The fruit is ready for harvest when its sugar levels are 20–24%. The grower assesses ripeness by testing the juice on an instrument called a refractometer, checking if the seeds have turned brown, or seeing if a berry can be easily pulled from its cluster.
The largest vineyards mechanically harvest their grapes, with one machine doing the work of dozens of hand pickers. Small vineyards producing boutique table wines still hand pick their crop.