Some form of the traditional Chinese calendar has been in use for three and a half millennia. It was borrowed by Japan, Korea, and Vietnam. Similarly, tea cultivation spread from China to these countries. As a result, tea growing culture in all of these countries incorporates “seasonal markers” that correspond with each other.
Up to speed on your astronomy? As the Earth orbits the Sun in the course of the year, our vantage point of the Sun against the backdrop of the stars changes. Simultaneously the Earth is rotating on its axis, but not in the same plane: it’s cocked over about 23 1/3 degrees. So when the Earth is in its orbit such that the Northern Hemisphere is cocked directly away from the Sun, we get the least sunlight of the year, at the winter solstice. At that time, the Earth and Sun are lined up such that the Sun appears “in” the constellation Sagittarius. When the Earth goes another quarter of the way around, it’s cocked neither towards nor away from the sun, but at a right angle. Daytime and nighttime are approximately the same length, it’s the spring equinox, and the sun is “in” Pisces. To make matters more complicated, the Earth’s axis is slowly wobbling, so starting in the year 2597, the sun will appear “in” Aquarius during the spring equinox. So to keep a constant frame of reference, the Earth’s position around the sun during the spring equinox is described as 0° ecliptic longitude. 90° E ecliptic longitude is the summer solstice, marking off the next quarter of the 360° circle.
The Chinese calendar follows this framework. View the full chart on Wikipedia. It goes beyond our two solstices and two equinoxes, further dividing the year into 24 solar terms. Note that a solar term is properly a specific point or instant, and not an expanse of time. While we envision the spring equinox as the beginning of the spring season, a solar term on the Chinese calendar is conceived as the midpoint of a term which lasts around 15 days. Earth’s orbit is not a perfect circle, so these terms are not spaced exactly evenly. 15° of ecliptic longitude after the spring equinox, on about April 5, is the term 清明.
清明 translates to “clear and bright,” and the same characters can be understood as such in Chinese, Japanese, and Korean. In Chinese, it’s pronounced “qīngmíng.” In Japanese it’s “seimei,” Korean “cheongmyeong,” and Vietnamese “thanh minh.” In China, Qingming is a spring holiday, observed by remembrance of ancestors and tending their graves, but it’s relevant because it’s used as a seasonal marker for tea quality. The first tea harvest, mingqian, is plucked right before Qingming, and the buds have built up nutrients through the dormant season, rendering their quality legendary. Here’s a Qingming discourse at teageek.net occasioned by a famous painting.
The next solar term, on about April 20, is 穀雨, “gǔyǔ” in Chinese, or “gogu” in Korean, translated as “Grain Rain.” Tea growing regions in Korea are farther north, so generally colder. So Gogu, or Gokwoo, serves as the seasonal marker for tea in Korea, as it takes longer to achieve the sufficient warmth. Pre-Gogu Korean tea is known as Ujeon-cha, and treated with similar reverence. MattCha deflates the hype here. Oops, got to run to a business plan coaching session. Have a happy Lichun, and Chinese New Year!