In what month was the Toona sinensis bud picked?

Toona sinensis is picked from late March to early April every year. Toona sinensis generally germinates before Tomb-Sweeping Day, and the terminal buds can be picked before and after Grain Rain, and then picked for the second time every 15~20 days according to the growth situation. The new species of Toona sinensis can be harvested at most twice a year, and two or three times a year after three years. After mid-April, the nitrate content in most Toona sinensis buds exceeded the standards of the World Health Organization and the Food and Agriculture Organization of the United Nations, and it was not suitable for eating.