Ujeon, Sejak, Joongjak: The Solar Calendar in Your Cup
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Ujeon, Sejak, Joongjak: The Solar Calendar in Your Cup
Why does the harvest date change everything about the taste of Korean tea? Complete guide to Boseong and Hadong harvest grades, from the rarest to the most accessible.
By Maison Boseong · Seoul, South Korea · June 2026 · 7 min read
As you browse the Maison Boseong shop, you'll notice recurring names: Ujeon, Sejak, Joongjak. These are not different plant varieties. They are temporal markers, precise moments captured in the leaf. In Korea, we don't just "harvest tea." We capture a moment of spring.
The Korean Solar Calendar and Tea
The Korean lunar calendar divides the year into 24 solar periods (절기, jeolgi), each corresponding to a precise moment in the natural cycle. Two of these periods are decisive for tea harvesting:
Gogu (곡우): the "grain rain", around April 20. 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 6. This is the boundary between Sejak and Joongjak. Leaves gain in size and body, losing a little of their springtime delicacy.
This temporal precision is not anecdotal. The earlier the harvest, the smaller the leaves, the more concentrated in aromas, and the rarer they are. The quantity produced before Gogu can be ten times less than that produced in May.
Ujeon
Aromas: Silky umami, fresh chestnut, complete absence of bitterness
Texture: Velvety, almost creamy
Infusions: 4 to 6 steepings
Sejak
Aromas: Roasted hazelnut, vegetal freshness, balanced umami
Texture: Light, clean, clear
Infusions: 3 to 5 steepings
Joongjak
Aromas: More body, notes of hazelnut and slight vegetal astringency
Texture: Robust, structured
Infusions: 3 to 4 steepings
Daejakcha
Aromas: Full-bodied, tannic, bitter if over-steeped
Texture: Dense, powerful
Infusions: 2 to 3 steepings
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 20, sometimes in a single morning if climatic conditions are not favorable.
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 first tiny shoot has an incomparable aromatic density.
In the cup, Ujeon offers a unique experience: a deep silky 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", the Perfect Balance
Sejak is harvested right 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 curved, pointed like a small bird's tongue.
This is the quintessential Korean tea, the one that best expresses the identity of the Boseong terroir: springtime 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 Hadong Grand Cru Sejak 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 Sejaks.
« In Korea, we don't just harvest tea. We capture a precise moment of spring. Each leaf is a photograph of the day it was picked. »
Joongjak (중작): "May's Maturity", Daily Strength
Harvested in May, Joongjak uses slightly larger and more mature leaves. The name means "middle harvest" (중 = middle/medium, 작 = harvest). After the Gogu rains, the tea plants' growth accelerates under the warmth of May. The leaves are larger, and the yield is 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 is best expressed in raw stoneware bowls that temper the extraction. It is the tea for daily efficacy, 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 high-consumption teas.
Balhyocha (발효차) is an exception: it is a semi-fermented tea produced 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
| Grade | Period | Water temp. | Steeping time | Aromatic profile |
|---|---|---|---|---|
| Ujeon (우전) | Before April 20 | 60–68°C | 45–60 sec | Silky umami, zero bitterness, creamy |
| Sejak (세작) | Mid-April to early May | 65–75°C | 60–90 sec | Roasted hazelnut, freshness, balanced umami |
| Joongjak (중작) | May | 75–80°C | 90–120 sec | Present body, slight astringency, frank vegetal |
| Daejakcha (대작차) | June+ | 80–90°C | 2–3 min | Full-bodied, tannic, powerful |
| Balhyocha (발효차) | Spring | 75–85°C | 30–60 sec | Fruits, honey, minerality, complex |
How to Prepare Each Grade
🌱 Ujeon · Ceremony
Water: 60–68°C (never more)
Quantity: 2–3g / 100ml
Duration: 45–60 seconds
Vessel: White porcelain bowl to admire the pale liquor
Steepings: 4 to 6 successive infusions
🍵 Sejak · Daily and tasting
Water: 65–75°C
Quantity: 3–4g / 150ml
Duration: 60–90 seconds
Vessel: Stoneware teapot or celadon bowl
Steepings: 3 to 5 infusions
💪 Joongjak · Robust and daily
Water: 75–80°C
Quantity: 4–5g / 150ml
Duration: 90–120 seconds
Vessel: Raw stoneware bowl
Steepings: 3 to 4 infusions
Why Sources Contradict on Dates
If you've searched for information on Korean tea grades in English, you've probably noticed something unsettling: almost no sources give the same dates. For Joongjak alone, you can find "around May 20," "early June," "May 5 to 21," or even "two weeks after May 5." Some sources even dispute the order of the grades or add a fifth level, Maljak, which others completely ignore.
This isn't negligence. These discrepancies have three precise, rarely explained causes, and understanding them is the only way to correctly read a Korean tea label.
1. The lunisolar calendar does not fall on a fixed date
Korean harvest markers are not Gregorian calendar dates: they are jeolgi (절기), the 24 solar periods of the traditional calendar. Gogu, the "grain rain," falls around April 20, but can shift to the 19th or 21st depending on the year. Ipha, the beginning of summer, similarly oscillates around May 5 and 6. A source that writes "April 20" and another that writes "April 21" are therefore describing the same marker, simply translated differently.
2. Terroir shifts the actual calendar
The same date does not mean the same stage of growth depending on the region. Jeju, a volcanic island with a subtropical climate, sees its tea bushes bud significantly earlier than the high-altitude gardens of Hadong, on the slopes of Jirisan, where the cold delays sprouting by one to two weeks. Boseong, on the coastal plain, is somewhere in between. A Jeju Sejak and a Hadong Sejak can thus be picked fifteen days apart while bearing the same name.
3. Grade by date or grade by leaf size
This is the deepest source of confusion, and the one that explains the most vigorous disagreements. Two logics coexist in Korea:
The calendrical logic, dominant in export and Western literature, classifies teas by picking date: Ujeon before Gogu, Sejak after, and so on.
The morphological logic, still used by some traditional producers, classifies by leaf size and maturity: "se" (세) means fine, "joong" (중) medium, "dae" (대) large. In this reading, the word Ujeon is not a grade in the same way as the others; it is a mention of primeur that superimposes itself on the system.
This is why some authors assert that Sejak is the first grade and not the second: they apply the morphological logic, where Ujeon is a category of its own. Both readings are defensible. They only appear to contradict each other.
Our selection by grade
From exceptional Ujeon to daily Sejak, the grades of Boseong and Hadong.
Ujeon · Prestige · Before April 20
Grands Crus Ujeon
The rarest grade. Silky umami, zero bitterness, harvest window of less than 10 days per year.
DiscoverSejak · Grand Cru · Mid-April
Boseong and Hadong Sejak
The perfect balance of freshness and character. Maison Boseong's daily reference.
DiscoverGift Set · Grade Comparison
Discovery Gift Sets
To compare Ujeon, Sejak, and Joongjak in a single session. Ideal for understanding grades through tasting.
DiscoverFind your ideal grade
Ujeon, Sejak, Joongjak: all grades of Korean tea, selected in Seoul. Code BIENVENUE10 for 10% off your first order.
Grand Crus All CollectionAbout the author:Nico Lesage is the founder of Maison Boseong. An expert in Korean teas, he has lived in Seoul since 2011. Every year, he travels to the peninsula’s tea gardens to source exceptional harvests directly from local producers.