Trim through summer

Trim through summer

Article originally published by: Kiwi Gardener

Hannah Zwartz explains the importance of giving grapevines a prune through summer, as well as in winter.

Gapevines are pruned in winter, right? Not exactly. Grapes are cut back hard in winter, while dormant, to create a basic framework. But ongoing summer pruning is also important for healthy crops. I’ve been growing fantastic grapes for a few years now on a Clearlite-covered verandah. Each year, I learn more about pruning – and each year I find myself pruning more and more ruthlessly.

The first step, as with any pruning, is to understand the plant’s growth cycle. Grapes have a rapid rush of leafy growth in spring, growing as much as a centimetre per day. Within two months, flowers appear and fruit are set on the new growth; on my vine this means usually two to three bunches on the nodes closest to the woody framework.

After that, the plant’s energy, tapped from the sun by the large leaves, goes towards creating sugars to ripen the fruit and starches to create the vine’s long-term woody framework. This woody growth is where the vine stores energy during the dormant winter period.

But, after the first few years, once a grape has covered its support structure, you want it to focus instead on producing fruit. Hence the cutting back of any parts of the vine not bearing fruit – you are saving the vine the trouble of creating wood that you’d only chop off in winter. Flowers appear in mid-spring, between the third and fifth leaf along the stem. Most cultivated vines are hermaphrodites, having both male and female sex organs, so they don’t need another vine to pollinate. The green flowers are wind-pollinated, so also don’t need bees or other insects.

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Flowers appear on the first few buds of the new growth, quickly followed by baby fruit.
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Shorten leafy growth, cutting back to a few leaves past the setting fruit.

Pruning

After three leaves beyond each flower, cut off the new growth. Any shoots without fruit can be totally removed. On new vines, you’ll need to spend some time training new shoots, tying them in while still green and flexible, so they grow in a well-spaced framework on their supporting structure. Left to their own devices, vine shoots often twine together, creating a tangle – spreading them out, let’s all the bunches of grapes get sunlight and airflow.

After three years, the basic structure will be in place. Summer pruning of grapes is not a one-off event, as the vine responds to pruning by growing more leaves and more shoots. It requires ongoing pottering all summer. Once bunches start to ripen, make sure they are getting sun.

Many growers recommend thinning the number of bunches to no more than two per metre of stem. Thinning is not essential, but creates larger, better-quality fruit. If you are going to thin, do it while the fruit are young, so as not to waste the plant’s energy.

For maximum flavour, hope for a hot, dry autumn. Humid weather promotes rots, so if your climate is humid you may need to thin out more leaves and fruit. Winter pruning Because grapes crop on new wood each year, all laterals (side branches of the vine) are cut back hard to one or two buds each winter.

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You will create a large pile of prunings – pruning can be repeated all summer to remove excess foliage.
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Each bunch of fruit needs sun to ripen (more leaves can be removed later) and airflow to prevent fungal disease.

Grape leaf

Fresh, young leaves can be used in dolmades (Greek vine-leaf rolls). To make dolmade filling:

  1. Gently fry onion, garlic, pine nuts/mince and flavourings of your choice and stir in some raw rice.
  2. Blanch the vine leaves with boiling water then place them shiny side down, put a small amount of filling in the middle and roll up, tucking in the sides.
  3. Arrange the dolmades in layers, seam side down, in a large heavy pot.
  4. Pour over stock, lemon juice and a little olive oil and lay a heavy dish on top to keep them from unwrapping.
  5. Simmer uncovered for 1-1½ hours.