Early. According to the official website of China Agricultural Information Network, black leaf cabbage planted in March to April each year, black leaf cabbage root water demand is low only to keep the soil moist can be, March to April temperatures are dry to facilitate the planting of black leaf cabbage, cabbage planted in July to September each year, cabbage seedling period of water demand, this time the weather is cool, rainfall, can improve the survival rate of the heart of the cabbage and the development of the speed.