Napa cabbage
Napa cabbage needs much water during the whole growth period. Often an irrigation system is needed, especially for August and September. The required amount of water depends on the stage of crop growth, weather conditions, and soil type. The most critical stage after establishment is when the head is forming. Inadequate water at this time will result in reduced uptake of calcium. This condition causes dead leaf tips within the head which makes it unmarketable. During head formation, of water per week is needed to maintain sustained growth rates.