Bleaching to achieve delicate petioles occurs in the first half of September, when the plants are fully developed.
Wrapping paper is used for bleaching, Corrugated cardboard or straw. During the bleaching period, light must not get on the petioles. To achieve that, you take the petioles of each plant tightly together and wrap them with one of the specified fabrics. There must be no gap between the lower edge of the envelope and the floor surface. At the top, the envelope ends at the beginning of the sheet. So the leaves remain free. The petioles also bleach, when the plants are piled up with earth, which is very cumbersome. In addition, the petioles take on the earth odor as well as other odors. That is why one must also pay attention to it, that the fabrics for covering are completely odorless.