In the Gregorian calendar, the Grain Full usually falls around May 21, and more often refers in particular to the day when the sun is exactly at the celestial longitude of 60°. Literally, this day represents the time when the seeds of summer crops begin to become plump but are not yet ripe.
In certain areas of Haining Zhejiang Province, the first and foremost custom on the day of Grain Full is the ceremony of “scrambling for water.” The ceremony goes like this: normally, waterwheels used for irrigation begin to run on Grain Full, and people hold a ceremony around the waterwheels to worship the god of waterwheels, and then begin to run the wheels to pipe water into the field from a nearby river.
Another custom, similar to the first, is called “worshiping the god of waterwheels.” On this day, farmers put fish, meat, candles, and, in particular, a cup of water in front of waterwheels, and then pour the water into the field. The ceremony embodies their desire for favorable weather and a good harvest.
During Grain Full, people often eat marors, one of the earliest edible wild vegetables in China, as well as other vegetables such as red beans, mung beans, melons, cucumbers, lilies, watercress, black fungus, carrots, and tomatoes to clear out the heat and eliminate dampness.