The method for producing the seeds includes sowing seeds of biennial plants in a paper cylinder followed by vernalizing so as to obtain paper cylinder seedlings, fix planting the paper cylinder seedlings in a field in spring followed by developing flower stalks and fructifying, and gathering the seeds. 2年生植物の種を紙筒内に播種し、春化処理をして紙筒苗を得、該紙筒苗を春に圃場に定植することにより、抽苔、結実させて採種する。 - 特許庁