When is the best time to dig water chestnut?

When entering beginning of winter, the precocious water chestnut began to harvest, but at this time, the starch content of bulbs was not high, and the sugar content was even less. After winter solstice, the starch content gradually increased and began to transform into sugar. The slight cold solar term is the most suitable time to harvest bulbs with the highest sugar content, bright red skin and the best quality. After the spring, the quality is declining day by day.