Early winter is a perfect time to prune your grape vines. By now you would have enjoyed a delicious summer/early autumn crop and all of the leaves will be falling off, leaving the plant dormant until spring.
Pruning is important to maximise your chances of a successful harvest next season, so that the energy is going into developing grapes, rather than developing woody grape vines, of which most parts are unproductive.
Pruning also helps to protect from disease and pests, as grape vines thrive best with lots of air circulation throughout the vine.
Thirdly, pruning helps with access and harvesting and aesthetic reasons – to avoid a tangled web of trunks and foliage that can result from leaving your grapevine to go au naturale.
There are two types of pruning – cane pruning and spur pruning. Cane pruning is the typical method used for home grape vines in New Zealand.
If it’s your first winter with your grape vine, pick the main strongest looking shoot (cane) coming off the stem and cut leaving 2-3 nodes (these are the little bumps that burst forth again in spring). Remove all other canes and leaves. This is to establish a strong foundation for your developing grape vine, otherwise weight of the fruit will weaken or damage the plant.
The next winter, select two strong canes and attach them to a trellis or the like. Cut them right back leaving 2-3 nodes and remove all other canes and leaves.
In subsequent years, or if your grape vine is already established, trim the canes back so that the length remaining has only 2-3 nodes.
Grape vines put on a lot of growth come spring, so don’t be alarmed by giving your vine a hard prune. It will recover and thrive! A hard prune will maximise your chances of a bumper crop next season, whilst reducing the chances of it developing disease or getting rampaged by pests.
As spring approaches, keep a watchful eye on new early spring growth. If there is a chance of a late frost that sometimes sneak up on us, protect with frost cloth as at this time, the new growth is susceptible to damage.
As it warms and your grape vines bounce back, if foliage is dense, you may like to give a light prune of some leaves to allow developing bunches of grapes a more optimal chance.
Grape vines are easy to propagate, so while you are doing your winter pruning, you might like to take some cuttings, place in some potting mix and create a new plant. Take a cutting of approximately 15cm that has at least 4 nodes on it. Cut horizontally directly below one node from which roots will develop and diagonally 5cm or so above another node, from which the plant will develop. Pop into potting mix in a sunny and light, free draining area outside or start in pots to be transferred later if you prefer. You will need to protect from frosts.