Every tea in the world comes from the same plant. What separates a Longjing from a Dianhong from a fifty year old sheng is what someone did to the leaf in the hours and days after it was picked, and in a few cases the decades after that. The species is the same and the garden is often the same.
Two questions decide which category a tea belongs to.
The first is what happens to the enzymes. A fresh tea leaf carries polyphenol oxidase and peroxidase, and the moment the cell walls break those enzymes meet oxygen and begin converting catechins into theaflavins and thearubigins. The leaf darkens, the astringency softens, the aroma turns from green toward fruit and malt. This is oxidation, and it is chemistry happening inside the leaf with no help from anything else.
Heat stops it. Somewhere between 70 and 100 degrees Celsius those enzymes denature and the process halts wherever it happened to be. That step is 杀青, shā qīng, kill-green, and where a producer puts it in the sequence is the single largest decision in tea making. Apply it immediately and you have green tea. Apply it after the edges of the leaf have been bruised and left to turn, and you have oolong. Never apply it at all and let oxidation run to completion, and you have red tea.
The second question is whether microbes get involved after the fact. Fermentation in the strict sense means bacteria and fungi eating and transforming the leaf, and it only happens in two of the seven categories. It requires a substrate the enzymes never fully left, which is why sun-dried green material sits underneath both of them.
Everything below follows from those two questions. The rest is heat, moisture, air, pressure, and time.
One note before the categories. Flavor and aroma are the easiest things to talk about and the least reliable things to judge a tea by. Body, mouthfeel, and qi tell you more, and they are much harder to fake. Processing shapes all of it, so where we can we have said what a method does to the feel of a tea and not only to its taste.
This is nowhere near exhaustive. Every category below has regional variations, house styles, and arguments among people who have spent their lives on one of them, any of which could fill a post of its own.
White 白茶
Nobody does less to a leaf than a white tea producer.
There is no kill-green and no rolling. The leaves are withered, sometimes for two or three days, across bamboo trays in shaded rooms or in filtered sun, and then they are dried. That is the entire process on paper.
In practice the withering is where all the skill lives. The leaves lose most of their moisture slowly, and while they do, a small amount of oxidation happens on its own, because nothing has been done to stop it. Producers control this by moving trays between sun and shade, opening and closing windows, watching humidity. A white tea withered badly tastes flat and papery. One withered well carries honey, hay, melon, and a cooling quality in the body that the better ones keep for years.
The grades come down to what was picked. Bai Hao Yin Zhen is buds only, off a narrow window in early spring, and it carries the highest price. Bai Mu Dan is a bud with one or two leaves. Shou Mei is later, larger, coarser, and cheaper, and it is the one we put away for twenty years. Silver needle drinks well young and tends to thin out with age. The rougher leaf has more to work with.
Because the enzymes were never killed, a white tea is never finished. It keeps changing in storage, slowly, and an aged white from Fuding at fifteen or twenty years old tastes nothing like it did when it was made. The sweetness deepens toward dried fruit and medicine. This is the quiet argument for buying more white tea than you can drink.
We brew young white cooler than most people expect and give it room to open. Aged white we brew as hot as we would brew puerh, because by then the leaf is dry and needs the heat. A good white leaves the mouth cool and faintly sweet several minutes after you swallow. A poor one shows up at the front of the palate and is gone by the second steeping.
Green 绿茶
Green tea is defined by how early the heat arrives.
The leaves are picked and given a short wither, sometimes only an hour or two, and then fired before any meaningful oxidation can begin. After that they are rolled into whatever shape the tradition calls for and dried.
How the heat is applied changes the tea.
- 炒青 chǎo qīng, pan-fired, pressed against a hot wok by hand. This is Longjing, and the toasted, nutty, chestnut quality in a good one comes directly from the pan rather than from the leaf.
- 蒸青 zhēng qīng, steamed. Faster and more even, and it preserves a bright marine greenness. The Japanese standard, and alive in China at Enshi Yulu.
- 烘青 hōng qīng, baked in an oven. Gentler, and common for the fluffier downy greens like Huangshan Maofeng.
- 晒青 shài qīng, sun-dried. The most important one to understand, because it is the only method that does not fully finish the tea.
Sun-drying reaches a lower temperature than a wok or an oven, so the enzymes are reduced rather than eliminated, and some microbial life survives on the leaf. The result is 毛茶, maocha, and it is technically a green tea. It is also the raw material for everything in the last two sections of this post. A tea that has been sun-dried is a tea that is still capable of change.
Ordinary green tea is not. Drink it inside the year and keep it cold and sealed. The bag from two springs ago is not going to improve.
Green runs cool in the body, which is why it belongs to the hot months and why it sits badly on an empty stomach. If a green tea pinches at the back of your throat, the water was too hot or the leaf was not good.
Yellow 黄茶
Yellow tea is green tea plus one more step. That step nearly took the category down with it.
The tea is picked, withered, and fired exactly as a green tea would be. Then, while the leaves are still warm and carrying moisture, they are wrapped in cloth or paper or packed into a sealed container so that heat and humidity cannot escape.
This is 闷黄, mèn huáng. 闷 is the character used in cooking for braising with the lid on, and it carries a sense of covering, smothering, sealing something in. The leaves sit in their own warmth for hours. Then they are opened, cooled, and often wrapped again, in cycles, over anywhere from a few hours to three days.
What happens inside the wrap is not enzymatic, because the enzymes are already dead. It is damp heat driving a slow non-enzymatic oxidation, with some microbial activity alongside it. The chlorophyll breaks down and the leaf turns from green to a soft gold. The grassy, slightly sharp edge that defines green tea disappears, and what replaces it is rounder, sweeter, and gentler on the stomach.
The window is unforgiving. Too little and you have a green tea that someone mishandled. Too much and the tea goes flat and dull.
The famous ones are Junshan Yinzhen from Hunan, Meng Ding Huang Ya from Sichuan, and Huoshan Huang Ya from Anhui.
Yellow tea is now somewhere around one percent of what the world produces. The reason is arithmetic. The sealing step adds days of labor and a skilled hand to a tea that will sell for roughly what the green version sells for. Most producers stopped, and a number of teas sold as yellow today are green teas with a yellow name on the wrapper.
If you are buying one, the tell is in the dry leaf. A tea that has been through mèn huáng has gone soft gold the whole way through. A green tea wearing the name is still green in the middle.
Oolong 乌龙茶
Oolong is not a point on the oxidation scale. It is the entire middle of it, from around ten percent to around eighty, and the category holds teas that resemble each other less than they resemble their neighbors on either side.
The step that makes an oolong an oolong is 做青, zuò qīng.
After a sun wither and an indoor wither, the leaves are shaken, tossed, or tumbled in bamboo trays. The point is to bruise the edges while leaving the center intact. Then the leaves rest. Then they are shaken again. This repeats through the night, six or eight or ten times, with the producer judging by smell and by the feel of the leaf when to move and when to wait.
The bruised edges oxidize while the protected centers stay green, and a properly made oolong leaf shows it: 绿叶红镶边, a green leaf with a red border.
When the oxidation has gone as far as intended, the leaf is fired to stop it, then rolled. Two shaping traditions:
- Strip style, as in Wuyi yancha and Phoenix Dan Cong, where the leaf is rolled long and twisted.
- Ball-rolled, as in Anxi and most of Taiwan, where the leaf is wrapped in cloth and pressed and rolled repeatedly, sometimes thirty or forty cycles, until it forms tight beads.
Then some of them go to fire.
Roasting is a second craft sitting on top of the first. The tea goes into baskets over charcoal, or into an electric oven for the modern approach, and it comes out and rests and goes back in. Three passes is common. Some teas are roasted on and off across months.
The roast is doing more than drying. It caramelizes sugars in the leaf, drives off the last of the moisture so the tea will keep, and rebuilds the aroma from the inside out. Between passes the tea has to rest, because a freshly roasted oolong tastes harsh and disjointed and needs weeks or months before the roast integrates.
A light roast leaves the florals sitting near the surface. A heavy one buries them and brings up cocoa, char, dried fruit, and mineral. Neither is better. They are different intentions, and a well-roasted oolong ages for decades while an unroasted high mountain tea is asking to be drunk now.
Roast changes what the tea does in the body as much as what it does on the palate. A heavy roast warms, and it settles the stomach after a heavy meal. An unroasted high mountain oolong lifts, and it will leave you jittery if you drink it on nothing.
The market has spent twenty years chasing green, floral, lightly oxidized oolong, and a great deal of well-made traditional roast has gone cheap as a result. If you like the style, the teas are inexpensive right now.
Red 红茶
Red tea is the only category where oxidation runs all the way to the end.
No kill-green at any point. The leaf is withered, then rolled hard to rupture as many cells as possible, then spread in beds in a warm humid room for somewhere between two and six hours while it turns copper and the aroma climbs out of green into apple, then stone fruit, then malt. Firing at the end stops the enzymes and dries the tea in one move.
Qimen for cocoa and orchid on a thin wiry leaf. Dianhong for honey and sweet potato, off the same large-leaf assamica that becomes puerh. Jin Jun Mei for buds alone. Lapsang Souchong from Tongmu, where the pine-smoked version is what the West asks for and the unsmoked one is older. Most people who grew up with it prefer the unsmoked.
We brew red tea in a bowl or a side-handle pot with water just off the boil, and we give it several short steepings rather than one long one. Left to sit, it turns dry and tannic, which is most of where the Western habit of adding milk came from.
Red tea is stable. Age does little to it in either direction.
Black 黑茶
Here the microbes arrive.
黑茶 is post-fermented tea, which means that after the leaf has been processed the way a green tea would be, usually sun-dried, it is deliberately handed over to bacteria and fungi and allowed to transform again. The base material is almost always coarse, mature leaf rather than tender buds, because the process needs something with enough structure to survive it.
Two of them you are most likely to meet.
Liu Bao 六堡, from Guangxi. The leaves are piled and dampened so that microbial fermentation runs through them, then dried, and then traditionally aged in large woven baskets, sometimes for decades, sometimes in cellars. Older Liu Bao develops betel nut and camphor over a woody sweetness. Some of it is pine-smoked. It is the one dark tea that runs cool in the body rather than warm, which makes it useful in a way the others are not.
Fu Zhuan 茯砖, from Hunan, pressed into bricks and then deliberately colonized by Eurotium cristatum, a golden fungus that fruits visibly inside the brick. These are 金花, jīn huā, golden flowers, and a Fu Zhuan without them has failed. The tea is smooth, grain-sweet, and easy on the digestion, and it traveled north into the steppe for centuries as a vegetable substitute for people living on meat and dairy.
Anhua dark tea and the Sichuan border teas fill out the category.
Both want boiling water and both forgive a heavy hand. Fu Zhuan in particular is difficult to over-brew, which makes it a good tea to leave going on the desk through a working day.
Puerh 普洱
Puerh sits apart from the rest, and the reason is in the base material.
It starts as 晒青毛茶, sun-dried maocha, made from the large-leaf assamica varietals that grow in Yunnan. The processing to that point is a green tea process with the sun-drying variation described earlier, which means the leaf arrives at the next stage still alive.
From there it goes two ways.
Sheng 生茶 is left alone. It is sorted, sometimes steamed and pressed into cakes or bricks or tuocha, sometimes left loose, and then it simply sits. Whatever microbial life came in on the leaf and lives in the air of the storeroom does the rest, over years and then decades. A young sheng is bracing, bitter, floral, and aggressive. At fifteen years it is starting to settle. At thirty or forty, if the material was good and the storage was sane, it becomes something that no amount of technique can shortcut.
Shou 熟茶 is fermented on purpose. The method is 渥堆, wet piling: the maocha is heaped, dampened, and covered, and the pile generates real heat from the inside as the microbes go to work, sometimes past sixty degrees. It is turned and re-piled repeatedly for anywhere from forty to a hundred and twenty days. The method dates to 1973, developed at the Kunming and Menghai factories to produce in months something resembling what aged sheng took decades to become.
The two are not interchangeable and they do not converge. Aged sheng keeps more of the original tree's character and carries a stronger qi, because the transformation was slow enough that nothing got flattened. Shou arrives dark, thick, earthy, and immediately drinkable, and a good one is its own thing rather than an imitation.
There is a reason puerh comes from one province. The microbial ecology of Yunnan developed in response to that specific environment, and attempts to make puerh elsewhere from other varietals produce something nobody wants to drink. The place is as much the tea as the processing is.
Both forms want boiling water. Aged leaf is dry and brittle and will not give up its oils below that. Look for the qi more than the flavor here. A good aged tea arrives in the body before it finishes arriving on the palate, and that is the thing no amount of processing can counterfeit.
What It Changes
None of this is required in order to drink well. The tea teaches most of it eventually, and the body learns it faster than the mind does. We are tea nerds and we will happily spend an hour on oxidation percentages, but we also know that none of it is the point. You can know every stage of mèn huáng and still rush through a bowl without tasting it.
What the knowledge changes is what you notice. A roasted oolong that tastes harsh may only be young, and it will settle if you leave it alone through the winter. A white tea from ten years ago tastes better than it did new because nothing ever stopped it. A sheng that seems thin at five years may be exactly on schedule.
Seven categories from one plant. The difference between them is heat, air, moisture, and time in the hands of someone paying attention.
- When I drink a tea I love, do I know anything about how it was made? Does it matter to me either way?
- Where does knowing more deepen the practice, and where does it start to get in the way of it?
- Am I judging teas by flavor because flavor is the easiest thing to talk about? What happens if I go to the body first?
We hope this is useful the next time you are holding something you don't recognize.