Does Green tea age?
Green tea is the tea people most often try to age, and it is the one that least rewards it. Almost every green tea you can buy is made to be drunk within months of production. What you are paying for is freshness: the sweet, brothy note that comes from free amino acids, and the green top note that sits on top of it. Both fade.
Amino acids in stored green tea decline measurably within a year, and the fats and chlorophyll in the leaf oxidize into the flat, hay-like smell that everyone recognises as old green tea. Refrigeration slows this down a great deal, but it does not reverse it. A pouch opened in spring rarely tastes like itself by the following spring, even in a fridge.
The confusion is understandable, because the idea that tea improves with age is real. It just comes from dark tea and white tea, where it is true, and it gets applied to green tea where it is not. If someone tells you their green tea will be better in five years, ask what tea they are comparing it to.
There is also a difference between a tea that has been kept and a tea that has been aged. Kept tea is tea that has not yet gone off. Aged tea is tea that has become something different and better. Green tea can be kept for a year or two with care, and it never becomes the second thing.
If it ages: store for the long run
There is one real exception, and it is worth knowing because it explains a lot of confusing advice. Sun-dried green tea, the material called Yunnan sun-dried green or dian qing, is the raw material for raw pu-erh. It is dried in the sun rather than pan-fired, so its enzymes are not fully deactivated. That leaf does continue to change over decades.
But sun-dried green is not sold as green tea. Once it is compressed into a cake and left to age, people call it raw pu-erh, not green tea. If you are holding ordinary pan-fired or steamed green tea, the honest advice is to drink it this year.
If you do find genuine sun-dried material and want to keep it, the conditions are the same as for raw pu-erh rather than for green tea. Around 60 to 70 percent relative humidity, some air exchange, and no sealing in plastic. That is a different hobby from drinking green tea.
If it does not: drink it
Two other cases come up and are worth ruling out. Roasted green teas such as hojicha and some Japanese bancha keep longer than delicate steamed greens, but that is because they have less aroma left to lose, not because they improve. They hold steady and then decline.
And high-mountain green teas made from mature leaves have more structure than a bud-heavy tea like Biluochun. They may last two seasons instead of one. That is a difference in how long they stay pleasant, not a reason to lay them down for years.
The general principle is simple. Tea that tastes good because it is fresh cannot be improved by waiting. Tea that tastes harsh because it is young sometimes can. Green tea almost always falls into the first group.
If you want a concrete test, buy two 50 gram packets of the same green tea on the same day. Drink one now and seal the other in the fridge. Open it in twelve months and brew them side by side. Almost everyone prefers the fresh one, and it is a cheap experiment that settles the question for your own taste.
A simple smell test
Before you put anything aside, smell the dry leaf. Sweet and vegetal means it still has aroma to lose, so drink it while it is good. Flat or hay-like means nothing is coming back. Drink it now, or let it go.
The practical rule for green tea is to buy in small quantities, ideally 50 to 100 grams at a time, and to buy twice a year rather than once. That gives you fresh tea all year and removes the question of storage almost entirely.
If you buy in bulk anyway, split it into two sealed portions and only open one. Put the reserve in the fridge at 0 to 5 degrees Celsius in a moisture-proof container, and let it come back to room temperature before you open it, so condensation forms on the outside of the tin rather than on the leaf.