[rsync]

Is there a "bottom" to the greenhouse ?

Grape vine roots grow quite deep and at some point there is no need to water them at all, especially if you are controlling heat and humidity with a greenhouse.

However, if the root depth is limited I suppose you would need to water them forever ...

[veemjeem]

Plants grown in hydroponic systems tend to have shorter roots because plants don't need to grow deep to acquire the same amount of water. If you ever looked at roots in soil, you may notice many roots branch off into very fine whiskers, almost like the capillaries in our vascular system. Plants grown in hydroponics lack this whisker-like growth because it doesn't need it. Depending on the hydroponic configuration, long roots may not matter at all. For example, in a deep water culture grow, a very long root would just curl up inside the bucket, so it doesn't matter as long as the bucket has enough volume for all the roots.

[jmheflin]

You totally nailed it. I would just add that I am growing these vines for only 6 months before harvesting the fruit and discarding the cutting. They do not have time to put out really long roots. In addition, air pruning of the roots happens naturally when they run out of grow media, so they never get too long.

[pvaldes]

That would became a serious risk of Philoxera, as those are stems rooted, therefore not grafted.

[082349872349872]

I doubt it's in the european context, as it seems unlikely these would qualify for AOC/DOC/AOP.

https://www.inao.gouv.fr/content/download/1840/18727/version... (VI - Conduite du vignoble / 2° - Autres pratiques culturales) contains:

> "Toute modification substantielle de la morphologie, du sous-sol, de la couche arable ou des éléments permettant de garantir l’intégrité et la pérennité des sols d’une parcelle destinée à la production de l'appellation d'origine contrôlée est interdite, à l’exclusion des travaux de défonçage classique."

which suggests hydroponics would not be kosher, being modification of the arable layer.

Indeed, looking at the local AOC cahier, within each commune we only allow production from certain parcels.

(We have a lot of hobby vignerons, the smallest registered vineyard here being only 0,16 ha, so I doubt grapes are a bottleneck.)