Definition - What does Own-Rooted Vine mean?
An own-rooted vine is a vine (typically Vitis vinifera) which has been allowed to grow in the ground rather than be used as a graft upon a Vitis labrusca vine.
Own-rooted vines start out as a cutting with two buds that are placed in the ground. The buds will naturally grow roots. Three buds are allowed to remain above the ground in order to eventually grow leaves and grapes.
WineFrog explains Own-Rooted Vine
In order to cultivate an own-rooted vine, a cutting, which can be obtained during vineyard pruning, must be at least five buds long. This creates backup buds for roots and leaves. It is also important to secure the cutting which is placed in the ground with a stick to hold it upright.
The benefit of cultivating own-rooted vines is that they will behave maturely many years before grafted vines will. They also need less water to establish themselves as they do not need to rely on American rootstock for food.