The Korean Solar Calendar and Tea

The Korean lunar calendar divides the year into 24 solar periods (절기, jeolgi), each corresponding to a specific moment in the natural cycle. Two of these periods are crucial for tea harvesting:

Gogu (곡우): the "grain rain", around April 20th. This is the boundary between Ujeon and Sejak. Gogu rains warm the soil, accelerate leaf growth, and mark the end of the most precious harvest.

Ipha (입하): the "beginning of summer", around May 6th. This is the boundary between Sejak and Joongjak. Leaves gain in size and body, losing some of their spring delicacy.

This temporal precision is not anecdotal. The earlier the harvest, the smaller the leaves, the more concentrated their aromas, and the rarer they are. The quantity produced before Gogu can be ten times less than that produced in May.

Ujeon (우전): "Before the Rain", the Rarest

Ujeon is the first cry of spring. Its name literally means "before the grain rain" (우 = rain, 전 = before), a direct reference to the Gogu period of the Korean solar calendar. These leaves are harvested before April 20th, sometimes in a single morning if weather conditions are unfavorable.

Throughout winter, the tea plant accumulates its reserves. The buds remain closed, slowly concentrating amino acids, essential oils, and aromatic compounds under the cold. When spring finally warms the soil, these buds open with concentrated energy. The tiny first shoot has an incomparable aromatic density.

In the cup, Ujeon offers a unique experience: a deep umami sweetness, an almost creamy texture, zero bitterness even if steeped too long. The liquor is a pale, almost transparent yellow-green.

Sejak (세작): "Little Sparrow's Tongue", Perfect Balance

Sejak is harvested just after the first Gogu rains, between mid-April and early May. Its poetic name, "little sparrow's tongue" (세 = small, 작 = peck/bird's tongue), describes the characteristic shape of the leaves at this stage: thin, slightly curled, pointed like a small bird's tongue.

It is the quintessential Korean tea, best expressing the identity of the Boseong terroir: spring freshness, roasted hazelnut notes from the Gamasot, and a persistent vegetal finish that gently returns after swallowing. It is the most versatile grade, excellent for ceremonial tasting as well as daily drinking.

Our Sejak Grand Cru from Hadong represents the best of this grade: produced by a small artisanal cooperative in the bamboo forests of Jirisan, with a more mineral and wild profile than plantation Sejak.

Joongjak (중작): "The Maturity of May", Daily Strength

Harvested in May, Joongjak uses slightly larger and more mature leaves. The name means "medium harvest" (중 = middle/medium, 작 = harvest). After the Gogu rains, the tea plants' growth accelerates under the May heat. The leaves are larger, the yield better.

In the cup, Joongjak is more robust: more body, more slight astringency, a more assertive flavor. It tolerates slightly hotter water (75–80°C) and expresses itself best in unglazed stoneware bowls that temper the extraction. It is the tea of daily efficiency, less precious than Ujeon or Sejak, but with a frank aromatic generosity.

Daejakcha and Balhyocha: Late Harvests

Daejakcha (대작차, "large leaf") is harvested from June onwards. The leaves are large, and the tea is full-bodied and tannic. Less prized for fine tasting, it is often used to produce blends or mass-market teas.

Balhyocha (발효차) is an exception: it is a semi-fermented tea made from spring leaves (sometimes Sejak, sometimes wild Hadong leaves) that undergo controlled partial oxidation. Its profile, similar to a high-altitude oolong, makes it one of the most complex and rarest Korean teas. To learn more, see our article Green or Black: The Secret of Transformation.

Complete Comparative Table

How to Brew Each Grade