The red head of small iron-headed cabbage refers to the phenomenon that the head of small iron-headed cabbage leaves is red. This phenomenon is due to the lack of iron, zinc and other nutrients in the growth process of small iron head vegetables, resulting in red spots on the leaves or the whole leaves are red. Red head phenomenon will affect the quality and taste of small iron head vegetables, and also have a negative impact on the healthy growth of plants. Improve through reasonable fertilization and adjustment of irrigation.