A small white cup of pale green-gold tea beside a mound of dark green needle-shaped loose tea leaves and a few fresh tea shoots on a wooden table

Green Tea: The Complete Guide

September 30, 2026

Green tea is leaf that was heated before it had the chance to change. Picked shoots of the same plant that makes black tea are steamed or pan-fired soon after picking, the heat stops the leaf's own enzymes, and what goes into the tin is still green in color and in chemistry. Much of what is worth knowing about green tea follows from that single step, from the taste of the cup to why it turns harsh in water that is too hot and why an open bag fades. The how tea is made guide covers the full sequence of withering, oxidation and firing across every kind of tea.

What makes tea green

Every true tea comes from Camellia sinensis. Left alone after picking, the leaf's own enzymes begin to oxidize it. Green tea is made by stopping that early. The fresh leaf is exposed to high heat, by steam or in a hot pan, before it is rolled and dried, which deactivates those enzymes. Researchers comparing the two methods found that pan-firing and steaming each changed the tea's aroma and its levels of amino acids and catechins in measurably different ways.

That difference is the first divide in green tea. Steamed green tea tends toward green, floral notes; pan-fired green tea toward a roasted, chestnut-like aroma. Neither is the better tea, and the choice comes down to whether the cup should taste of fresh greens or of something closer to roasted chestnut.

The Japanese styles, side by side

Japanese green tea is steamed to stop oxidation, and the styles are then separated by how the bush is grown, when the leaf is picked, and what happens after steaming. The definitions below follow those published by the Japanese tea company Ito En.

Style	How it is grown and picked	How it is made	What that does in the cup
Sencha	Open sun	Steamed and rolled	The most widely drunk and best-known Japanese green tea
Fukamushi sencha	Open sun	Steamed about twice as long as regular sencha	A stronger taste and a darker green color
Kabusecha	Bushes covered for about a week before picking	Steamed and rolled	Between sencha and gyokuro
Gyokuro	Bushes covered for about 20 days before picking	Steamed and rolled	Shade holds back the conversion of theanine into catechins, so the cup is lower in astringency and rich in flavor
Tencha and matcha	Shaded like gyokuro, first-picking leaf	Steamed and dried without rolling; stone-ground to make matcha	The whole leaf is drunk rather than steeped and discarded
Hojicha	Sencha or other green tea	Roasted at about 200°C, then cooled quickly	Brown leaf, roasted aroma; some caffeine is driven off and the cup is less bitter
Genmaicha	Sencha or other green tea	Mixed roughly half and half with soaked, steamed, roasted and popped brown rice	The savory note of roasted brown rice with the refreshing flavor of sencha

The Mariage Frères Fuji-Yama tea guide looks closely at one Japanese sencha from a Paris tea house.

Reading a green tea label

Four things on a label say more than any tasting note. The first is the style name, since the table above describes very different drinks under the one word green. The second is the picking. Ichibancha is the first picking of new shoots in the year; nibancha and sanbancha are the second and third. Shincha, "new tea," is the first-picking leaf sold fresh, prized for the scent of new leaves and lower in catechins and caffeine than later pickings, which makes it less bitter and astringent. The third is the date of packing or harvest, for the reasons in the storage section below. The fourth is the form: whole leaf, broken leaf, or bag, and the loose-leaf versus tea bags guide takes up that choice in full.

How to brew green tea

Water temperature changes what ends up in the cup. A 2006 study by Labbé, Tremblay and Bazinet at Université Laval brewed green tea at temperatures from 50 to 90°C, over steeps far longer than a cup's, and measured what came out. EGCG and three other catechins, the compounds behind much of green tea's astringency, were extracted best at the hottest setting, while caffeine extraction peaked at 70 to 80°C.

Ito En's brewing guidance puts numbers on it. The temperatures below are theirs; the right-hand column reads them against the extraction study.

Tea	Water	Leaf and time	Why that temperature
Gyokuro	140°F, about 60°C	2 teaspoons; 2 minutes	Keeps catechin extraction low, in keeping with the low-astringency leaf that shading produces
Sencha	180°F, about 82°C	2 teaspoons; 30 seconds	Below the heat that pulls the most catechins, with a short steep
Hojicha	200°F, about 93°C	4 teaspoons; 30 seconds	Ito En's hottest setting; roasting has already made the leaf less bitter

The simplest way to cool the water is the one Ito En describes: pour boiled water into the cup first, which drops it about 18 degrees, then pour it over the leaf. The green tea recipe guide walks through a first pot step by step, and the how to taste tea guide covers what to look for in the cup.

Brewing in Denver

Altitude works in green tea's favor. Water boils at 212°F at sea level and just under 1°F lower for every 500 feet of elevation, according to the USDA's Food Safety and Inspection Service, which puts a Denver boil at about 202°F. A Denver kettle starts roughly ten degrees closer to the right temperature. That is still well above what sencha wants, so the cup-first method above still applies. Hojicha, at 200°F, can take water straight from a Denver boil. The Denver altitude cooking guide has the rest of the numbers.

How much caffeine is in green tea?

Less than black tea and much less than coffee. The FDA lists 37 milligrams of caffeine in a 12-fluid-ounce serving of green tea against 71 milligrams for black tea, and cites 400 milligrams a day, about two to three 12-ounce cups of coffee, as an amount not generally associated with negative effects for most adults. Real cups vary with the style and the brewing. Shincha is lower in caffeine than later pickings; roasting drives some caffeine out of hojicha. Matcha is the case apart: the leaf is ground and drunk whole, so a bowl delivers everything in the leaf rather than only what water pulls out of it.

Matcha or green tea?

Matcha is green tea made a particular way. The International Organization for Standardization published a technical report defining it in 2022, with Japan's National Agriculture and Food Research Organization leading the work: new shoots grown under shade, processed with specialized machinery for a bright green color, rich taste and aroma. The shaded first-picking leaf is steamed and dried flat as tencha, then stone-ground, and Ito En notes that matcha is ground immediately before shipping. The real difference from sencha is in the drinking. Whisked into water, the powder is consumed whole. Like any green tea, matcha is best kept sealed, cool and dark, and used soon after opening.

How to store green tea

Catechins are a large part of green tea's character, and heat and, to a lesser degree, moisture break them down. A study by Li, Taylor and Mauer at Purdue University, published in the Journal of Agricultural and Food Chemistry in 2011, stored green tea extract powder across a range of temperatures and humidities for up to 16 weeks. The samples kept hottest and dampest lost the most catechins, with temperature the larger effect and humidity the smaller one. Degradation continued even below the powder's glass transition temperature.

Keep green tea cool, dark, dry, airtight and away from smells. An opaque tin with a tight lid, in a cupboard away from the stove and the window, handles the first four. A foil bag can go inside the tin with the air pressed out and the top folded and clipped. Dry leaf takes on the smells around it, so green tea should not sit beside coffee or a smoked tea, and a tin that held a flavored tea should be washed and aired before it holds a plain one. The pantry storage guide places tea on the same shelf as the spices for the same reasons.

The refrigerator helps only with sealed packages. Cold slows the breakdown, but the trip out is the risk: a cold bag meeting warm kitchen air collects condensation, and humidity was the other factor the Purdue study found degraded catechins in green tea powder. A sealed bag from the refrigerator should stay sealed until it reaches room temperature. An opened tin is better off in a cool cupboard than going in and out of the cold.

How long green tea keeps

The schedule below is a rule of thumb for freshness. It is not a figure from the Purdue study or any producer, and it is not a safety date.

Tea	Once opened, drink within	What fades first
Sencha, Chinese pan-fired greens	About two months	Aroma, then sweetness
Gyokuro	About six weeks	The rich flavor that shading built
Matcha	About a month	Color and aroma
Genmaicha	Two to three months	The toasted rice
Hojicha	Three months and beyond	Roasted aroma, slowly

Buy an amount that will be finished within that window. The loose-leaf tea storage guide covers the same questions across black, oolong and herbal teas.

Does green tea go bad?

The FDA's technical guidance on water activity notes that a food controlled to a water activity of 0.85 or less is not subject to its regulations for foods that support dangerous microbial growth. Tea that gets wet and stays wet is a different case: if it smells musty or shows mold, it goes in the bin. Short of that, old green tea has, in most cases, simply faded.

Is green tea good for you?

The National Center for Complementary and Integrative Health, part of the National Institutes of Health, summarizes the evidence. Studies of green tea and cancer have produced inconsistent results. In Asian populations but not Western ones, green tea drinking has been linked to a lower risk of coronary heart disease. In trials green tea reduced total and LDL cholesterol to a small extent, with no effect on HDL cholesterol or triglycerides. Its catechins and caffeine may have a modest effect on body weight. NCCIH reports no safety concerns for green tea drunk as a beverage by adults.

The cautions concern concentrated products, some medications and pregnancy. Liver injury, though uncommon, has been reported in people using green tea products, primarily extracts in tablet or capsule form, and people with a particular immune-system gene variant appear especially susceptible; NCCIH puts that variant at 5 to 15 percent of Americans. Green tea can lower blood levels of certain medications, including nadolol, atorvastatin and raloxifene, and NCCIH advises anyone taking medicine to talk with a health care provider before using green tea supplements. Because green tea contains caffeine, NCCIH advises keeping intake moderate during pregnancy.

Green tea and iron

Polyphenol-containing drinks reduce the absorption of non-heme iron from a meal. A 1999 study by Hurrell, Reddy and Cook in the British Journal of Nutrition measured iron absorption from a bread meal served with different drinks: beverages with 20 to 50 milligrams of polyphenols per serving cut absorption by 50 to 70 percent, beverages with 100 to 400 milligrams cut it by 60 to 90 percent, and black tea cut it by 79 to 94 percent. Green tea was not among the drinks tested, but its catechins belong to the same polyphenol family. The effect was measured with the drink taken alongside the meal, so tea taken between meals falls outside what the study tested.

Short answers to the rest

Why does green tea taste bitter? Water too hot, a steep too long, or both; see the brewing table. Does green tea have tannins? The astringent compounds are mainly catechins, which make up most of tea's polyphenols; "tannin" is the older, looser label often applied to them. Is fukamushi sencha a different plant? No, the same leaf, steamed about twice as long. Is hojicha still green tea? Yes, roasted green tea. What goes with green tea? Yuzu's sharp citrus sits well against the leaf, and the yuzu complete guide explains the fruit. How did green tea reach the West? The history of tea guide tells that story.

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