Type: Trees & Vines
Difficulty: Hard
Season: Spring·Summer
Sowing: Plant a sapling

Trees & Vines

Tea Plant

Camellia sinensis

Catechins, theanine · an evergreen for southern ground

The tea plant is an evergreen shrub grown for the leaves that become tea. In the milder south, around Boseong, Hadong and Jeju, it goes into open ground; further north it is grown in a pot and overwintered indoors or under eaves. It wants sun and free-draining acid soil, and once the soil is right it asks for very little. Young shoots are picked from late April through June, and white flowers open in autumn. The Donguibogam lists it in the Wood section as 苦茶, giving a slightly cold nature, a taste both sweet and bitter, and no toxicity.

Year-Round Calendar

Sowing

Harvest

Where It Grows

Main producer Major producer Latitudes at 18–25℃ Zoom and pan to explore · temperatures are rough zonal averages

Main producer Produces close to half the world's tea. Yunnan, Fujian, Zhejiang and Sichuan are the centres, and the small-leaved China type predominates. Harvest April, May
4. 4
5. 5
Main producer The growing areas are Assam and Darjeeling in the northeast and the Nilgiris in the south. Assam grows the large-leaved Assam type (var. assamica). Harvest March, April, May, June, July, August, September
3. 3
4. 4
5. 5
6. 6
7. 7
8. 8
9. 9
Main producer Grown on the highlands of the Rift Valley, it leads the country's black tea exports. Because this is equatorial high country, picking goes on with little regard for season.
Major producer Grown in the central hills, with grades divided according to elevation.
Major producer Grown around Rize on the Black Sea coast, and most of it is drunk at home. Harvest May, June, July, August
5. 5
6. 6
7. 7
8. 8
Major producer The growing areas are Thai Nguyen and Moc Chau in the northern mountains.

Its home is the subtropical uplands running from southwestern China (Yunnan and Guizhou) to Assam in India, so it cannot be pinned to a single country and no place-of-origin row has been set down. It divides into the small-leaved, cold-hardy China type and the large-leaved Assam type suited to warm places; Korea, China and Japan grow the China type, while India, Sri Lanka and Kenya grow mainly the Assam type. Transplanted to India and Sri Lanka in the 19th century and to Kenya in the 20th, it produced the map of growing regions we know today.

Optimum: 18~25℃
Range: 10~35℃
Hardiness: Half-hardy

An evergreen tree of warm, rainy places. It does best where the mean annual temperature is 13℃ or higher and annual rainfall is around 1,500mm, and it likes well-drained acidic soil (pH 4.5–5.5). A sustained spell below −10℃ scorches the leaves, so outdoor overwintering — getting through the winter in open ground — is difficult from central Korea northward. On hillsides where fog is frequent and the sun comes filtered, the new shoots are tender.

Harvested 3–4 years after planting. For three or four years after the seedling goes in, the tree is grown on with almost no leaf picked, and only after that are the new shoots stripped each year. There is no harvest in the year of planting, and once the tree is established it is picked for decades.

In Korea Southern Korea

Boseong in South Jeolla, Hadong in South Gyeongsang and Jeju are the growing areas. It is limited to the southern coast and hillsides where winters are milder; from the central region northward, overwintering in open ground is difficult, so it is planted in pots and brought indoors. The new shoots are stripped from late April through June.

How to grow

Light: Four to six hours of sun. Screen it with part shade against the strongest midsummer light
Soil and depth: Free-draining acid soil. It wants pH 4.5 to 5.5, so mix in peat and coarse granite grit
Spacing: 60 to 90cm between plants, 1.5m between rows. Pots of at least 30cm diameter
Watering: Water when the surface dries. Roots are shallow and dry out fast in summer, so mulch with straw or leaf litter
Feeding: Two feeds of organic fertiliser, in March and after the first picking. Never add lime: neutral soil stalls the plant
Harvest: Strip new shoots at one bud and two leaves from late April into May. A second flush follows in May and June. Pan-fire or steam and dry the picked leaf the same day

What makes the difference. Let the plant build for two or three years after planting and take almost no leaf. Constant stripping from a young plant stops its growth

Why this one is harder. Open-ground overwintering fails in central Korea and further north. Grow it in a pot, bring it in before the first hard frost, keep it at a sunny window and cut back on water. In southern ground, mulch thickly over the roots and shelter it from north wind

Common problems

Tea red spider mite You will see Leaf undersides go rough and the leaf colour fades yellow What to do Spray water hard onto the undersides. Numbers climb in dry weather, so check often through summer
Yellow tea thrips You will see New shoots curl and silvery scarring appears on the leaves What to do Pick off damaged shoots and set sticky traps
Tea leafroller moth You will see Leaves rolled and stuck together with a caterpillar inside What to do Pick off the rolled leaves and destroy them. Do not spray in the run-up to harvest

This page describes how a crop is grown and used. It does not claim health effects for any food, nor is it intended to prevent or treat disease. Component and study notes are references only and do not mean the same result occurs in people. Consult a medical professional about health concerns.

Health Benefits

What the Donguibogam records — nature, taste and the five names. The Donguibogam lists tea in the Wood section as 苦茶. It gives a slightly cold nature, with one source saying cold, a taste both sweet and bitter, and no toxicity. The plant is described as small, like a gardenia, keeping its leaves through winter, and the entry separates early-picked leaf, 茶, from late-picked leaf, 茗. It counts five names in all, 茶, 檟, 蔎, 茗 and 荈, and records that older writers compared the bud to a sparrow's tongue and a barley grain, calling it 雀舌 and 麥顆. Preparation is noted too: young buds are picked, pounded and pressed into cakes. This is a historical medical record and differs from modern medical judgment.

A list of famous teas by place of origin. The same entry names Yixing, Lu'an, Dongbaishan, Shenhuashan, Longjing, Minla, Shuku, Baoqing and Lushan Yunwu teas, saying all of them earned their names through the quality of their taste. It shows that classifying tea by growing region was already recorded in a Joseon medical text. This is a historical record and differs from modern medical judgment.

Shade growing and theanine composition. Analyses report higher theanine content in tea leaf shaded for a period before harvest. The same work sets out the pathway by which sunlight converts theanine toward the catechins. This concerns growing conditions and composition, and has nothing to do with preventing or treating disease.

Nutrition

Catechins (EGCG and others) (reported at 10 to 18% of dry leaf) — the polyphenols behind tea's astringency
Caffeine (around 2 to 4% of dry leaf) — an alkaloid contributing bitterness
Theanine (1 to 2% of dry leaf, higher in shaded leaf) — the amino acid behind tea's savoury depth
Aroma compounds (the profile shifts sharply during pan-firing or steaming) — volatile compounds that make up tea's scent

Catechins and astringency The astringency of green tea comes from its catechins. Dry leaf is reported at 10 to 18% catechins, with EGCG the largest share. The hotter the water, the more catechin comes out and the more astringent the cup. That is the reasoning behind brewing a first-flush tea at around 70C.

Theanine and shading Theanine is the amino acid that gives tea its savoury depth. Analyses report that sunlight converts theanine towards catechins, so leaf shaded for a period before picking carries more of it. Gyokuro and matcha leaf are grown under cover for exactly this reason. Even a single potted plant tastes different if a shade net goes over it two weeks before picking.

Caffeine content and brewing Dry tea leaf is reported at around 2 to 4% caffeine. What actually reaches the cup, though, varies widely with leaf quantity, water temperature and steeping time. Young buds carry more caffeine than the larger, later-picked leaves. For an evening cup, steep briefly or use late-picked leaf.

Pairings

○ Rice cakes and dasik — Astringency and sweetness push against each other in a useful way. That is why sweets have always been served alongside tea. A small bite of something sweet first makes the astringency less prominent.

○ Roasted brown rice — Roasted brown rice adds a toasted note and cuts the leaf per cup, which brings the caffeine down with it. A one-to-one mix of rice and leaf is the common ratio. Slightly hotter water is fine here.

○ Cold brewing — At low temperature far less catechin and caffeine come out, so the astringency stays light. Put the leaf in cold water and leave it in the fridge for six to eight hours. It is the easiest summer use for leaf from your own plant.

△ Empty stomach and late hours — Strongly brewed tea on an empty stomach can leave a burning feeling. It contains caffeine, so steep it briefly close to bedtime. Children and pregnant women may want to cut the daily amount or switch to late-picked leaf. Brew strength matters more here than the number of cups.

△ Strong tea with meals, and iron — Tannins in tea have been reported to lower the absorption of non-heme iron from plant foods. Anyone who needs to build iron intake is better off leaving a gap between the meal and the tea. Follow the specific interval your doctor or pharmacist gives.

△ Do not take pills with tea — Swallow tablets with water. Compounds in tea have been reported to affect the absorption of some medicines, so it is safer to keep dosing time and tea time apart. Check with a pharmacist if you take regular medication.

Varieties

Seedling-grown native stock (sapling) — Propagated from seed. Leaf shape and scent differ slightly from tree to tree
Yabukita (sapling) — A Japanese-bred cultivar planted widely in Korean tea gardens. Buds flush evenly
Assam type (large-leaf) (sapling) — Camellia sinensis var. assamica. Large leaves, used for black tea. Too cold-tender to overwinter outdoors in Korea

Source: Donguibogam, Wood Section 苦茶 · Rural Development Administration (Nongsaro) · Korea National Arboretum