A seven-year-old is a low temperature resistant plant that can be grown in a variety of ways.
The simplest cultivation method is to establish a multi-year plantation by sowing seeds directly into the field, from seedlings or vegetatively propagated by dividing clumps. Then we only use the leaves.New varieties introduced into cultivation in recent years allow the harvest of whole plants with a green colored stem 40-70 cm long, ending with a white onion 1/4 to 1/3 of the total length of the plant. It is important to choose a lighter, airy soil, as it facilitates the bleaching of plants.
A seven-year-old plant grown from seedlings gives an earlier crop. It can then be planted singly or double, for the collection of whole plants.
In Japan, seven-year-old seedlings are planted in furrows deep. 15 cm with a 9 cm distance in a row between the plants.
During vegetation, the plants are sprinkled with soil 3 or 4 times and harvested after bleaching the supposed stem.
