A change of homestead ownership is often accompanied by a façade restoration, which usually requires scaffolding. If the restoration work include the foundation, then the grapevine has to be completely removed. Otherwise, it can be sawn off at ground level and renewed. Here you'll find out what needs to be considered for such vine "renewal" or "renovation."
The renewal treatment should occur during the dormant winter period. If a front garden or similar exists, it is not necessary to saw off the vine completely. It can be taken down from the façade, cleaned up with some thinning out, and attached to a temporary trellis or even to the construction scaffolding, where it can grow and survive for a year. The thick trunks are amazingly flexible and are usually easily "laid down." However, if the vine is not flexible enough to be "laid down," then the vine is sawn off to one or several main trunks (Image 02). If there is a bulbous thickening of the trunk above ground level, then this is most likely a bud union and you must saw above it. The saw cut must be done at a slight angle so that no water can remain on the cut surface and destroy the wood. How about you "let the vine know" about your sawing intentions first?
If there are one or two strong new shoots (light brown wood) arising from the ground, pruning back will be slightly less radical, because these new shoots will become part of the new vine framework (Image 03). In spring, after pruning, one (Image 04) or several very long water shoots (Image 05) will grow from the cut surface. Initially they can all remain, because they supply the roots with nutrition and energy. Should the construction continue into summer, then the new shoots have to be protected and guided away from the façade.
The new shoots are so vigorous because all the energy in the roots is transferred to them. The shoots can grow 5-6m long and develop axillary shoots. However, this growth vigour means that the wood is more "spongy" and thus more susceptible to fungal diseases. It is therefore imperative to refrain from anything which would encourage growth even more: no watering and no fertilizing! By the following winter, you will have decided what type of further training the vine is to follow. For a free fan form, 3-5 shoots are left on the vine, and all others are cut off flush. For other training forms, only one shoot and some selected axillary shoots are kept. Now that the vine already has some branches, "training in the 2nd year" becomes obsolete but can immediately continue as described for training in the 3rd year.