Guyu occurs at celestial longitude 30°, around April 19-21. The name reflects its agricultural significance — abundant spring rains nourish young grains, the literal foundation of subsequent harvests.
Tradition: drinking new spring tea (Guyu tea is prized), eating "spring vegetables." Climate: warm and humid; the last cold snaps of spring; ideal time for tea-picking in southern China.
The name is traditionally unpacked as rain that gives birth to the hundred grains — rainfall becoming plentiful exactly when newly sown seedlings need it. Its three pentads are duckweed beginning to grow, doves shaking out their feathers as they call, and hoopoes settling in the mulberry trees. All three point at warming water, field work and sericulture, which makes this one of the most frankly agricultural groups in the whole seventy-two-pentad scheme. Guyu is not the wettest term of the year. Across most of China rainfall peaks in summer, and the plum rains and summer downpours carry far more water than anything in late spring. The name is about the fit between rain and farm work: rain arriving now falls at the sowing and transplanting stage, where it matters most to the eventual harvest. What the term records is what the rain is for, not how much of it there is.
Guyu closes spring: it is the last of the season's six terms and the mid-term of the Dragon month. Classical five-phase reckoning hands the final eighteen days of each season to the earth element, and for spring that stretch begins around Guyu and runs to Lixia. The term therefore sits on a hinge — wood has fallen back from its Rabbit-month peak into residual strength, earth is taking charge, and summer fire has not yet arrived. In practice Guyu moves no pillar and simply records that the Dragon month is half gone. The hidden-stems-on-duty doctrine gives the wood, water and earth concealed in the Dragon branch a run of days each, and by Guyu the earth stem is generally reckoned to be in charge, though the exact day-counts differ from one classical source to another. The climate-adjusting approach holds that the Dragon month is thick and damp with earth, favouring wood to loosen it and water to keep it moving — an emphasis that sharpens in the later part of the month.
In the hexagram-month scheme the Dragon month takes Guai (夬), five yang lines with a single yin still clinging above, Lake over Heaven. The traditional reading emphasises something almost finished but not quite: yang at full strength with one yin line left to resolve, which matches a spring about to end while summer gathers behind it. These pairings track the rhythm of waxing and waning qi and are not verdicts on fortune; what they offer is a direction of movement.
A folk observance in some regions honours Cang Jie, the legendary inventor of writing, at Guyu, connecting the term to the old story that grain rained down from the sky when the characters were created. That story does appear in early Chinese literature, but it was never attached to this solar term there; the link grew up later out of a resemblance between the phrases. Pairings of this kind are common, since calendrical names and local cults ran alongside each other for centuries and gradually borrowed from one another, and it helps to keep the astronomical layer and the folkloric layer apart when reading.
No. Across most of China rainfall peaks in summer, and the plum rains and summer storms deliver far more than late spring does. Guyu is named for the relationship between rain and farm work, not for volume: rain at this point falls during sowing and transplanting, when it counts most for the harvest. The term describes what the rain is good for, not how much of it falls.
No. Guyu is the mid-term of the Dragon month and indicates only that the month is half elapsed. In Bazi the month pillar turns at major terms: the Dragon month starts at Qingming and gives way to the Snake month at Lixia. Guyu still carries weight in a reading, because under the hidden-stems-on-duty arrangement the earth stem is generally considered to have come on duty by this point.
The legend that grain fell from the sky when Cang Jie invented writing does appear in early Chinese literature, but it is not connected there to this solar term. The association arose later, in certain regions, from a similarity between the phrases, and it belongs to folk custom rather than to calendrical doctrine. Keeping the astronomical sense of the term separate from the stories that gathered around it avoids confusion.