Stratification is a crucial stage for the proper formation of the graft union. The stratification process is carried out in a heat chamber at 22 to 30°C with a high humidity level (100%). Callogenesis, the process of graft union formation, allows the joining of the rootstock with the vinifera.
In the photo, we can observe how once callogenesis is formed, the plants begin to sprout and soon after, roots start to develop.
The next phase is waxing; it is important that the wax thoroughly covers the graft union to prevent it from drying out once planted in the nursery.