Your grapevine can become unkempt if you skip winter pruning just once, and after a few years the neglect is devastating. Even vines which have been pruned incorrectly are easier to restore and bring back to fruiting than non-pruned ones! However, you may salvage a neglected vine with some rigorous restoration pruning.
A vine can be old and gnarled, with thick and entangled stems and still be perfectly healthy. The branches are trained close to the wall, the plant has lush foliage and is often green down to its base (Image 01), leaves and grapes are healthy.
Not so in Image 02: A neglected vine on a façade has an abundance of branches with weak shoots and often diseased leaves. Occasionally, there is also a lot of deadwood in amongst the branches. Foliage is usually sparse, the plant grows away from the wall and most of the greenery is at the top of the plant.
This question depends on whether the plant is infected with mildew. The expert can also identify this disease in winter by the dried up berries, which usually remain on some grape bunches. Split berries with the seeds showing through are an unmistakable sign of severe mildew infection. Lilac coloured, cancellate to patchy discolourations on the usually light-brown canes from the previous year also indicate mildew.
Mildew can also affect a usually robust and even fungus-tolerant grapevine, if it has been neglected, however this alone does not necessarily require removal of the vine. Today however, there are plenty of new, fungus-tolerant varieties, which may be neglected for some time and their entangled canes become a headache only after a few years. Such vines are definitely worth keeping.
However, if a vine combines all the above symptoms with low vigour and mildew as illustrated on Image 02, the vine cannot be rescued without professional spraying and it is better to remove the entire plant.
If the vine is to be retained, the first step is to pre-prune the stem framework by either shortening the thick stems or, depending on the overall shape (Free Fan Form), cutting them off completely. Next, many of the remaining thinner shoots are removed. In the end there will be some well lignified canes from the previous year - recognised by their light brown, grey brown or brown red colouring - arising from the stems at about 15 to 60 cm spacings. These shoots are later trained to new side shoot positions, therefore they should arise directly from or as close as possible to the stem framework, the most suitable being the water shoots from the previous year. Of these shoots, the more basal ones are usually pruned shorter (Spur Pruning and Rod Pruning), the upper ones a bit longer (Rod and Cane Pruning or Arched cane pruning).
If there are no previous year's canes arising from the stems and only the stem framework remains, then new shoots will grow from dormant eyes, as happens in Vine Renewal.
Training of the canes can now be done according to the desired form. Usually this is the free fan form initially (Image 03). This is followed by Tying. All new shoots with more than 4 - 6 eyes are then tied horizontally, if this is possible without breaking off the shoots. Tying them this way will ensure an even bud break. In the following years the new side shoot positions are further trained according to the desired form.