The short answer
Dark tea is the one category where old is usually the right answer, and it is still not a simple one.
Ripe tea is ready when it is pressed and changes little afterwards, so for ripe the answer is whenever.
Raw tea is genuinely unfinished when young, and most people find it harsh and astringent for the first few years.
So for raw the answer is old, with the caveat that old has to mean well-stored.
A raw cake at ten years is a different drink from the same cake at two.
A ripe cake at ten years is slightly cleaner than the same cake at two, and that is about it.
If you want to drink something this month, buy ripe, and buy it from a known factory.
Keeping something means raw tea from a documented recipe, forgotten about for a decade.
The middle option, buying raw and drinking it young, is what most beginners do and mostly regret.
So: ripe for now, raw for later, and do not pay a premium for age on ripe tea.
Why age matters differently
Ripe tea has already been through a fast fermentation in the pile, which takes weeks rather than decades.
That process does most of the work that ageing would do in a raw tea, and it does it immediately.
What is left for ripe tea is a slow mellowing: the fermentation flavour fades and the tea gets a little cleaner.
Raw tea has not had that process, and the years in storage are what perform it.
Microbes and slow oxidation break down the catechins that make young raw tea harsh and bitter.
The result after a decade is darker liquor, thicker body, and a sweetness that was not there at the start.
This is the only tea where the change is genuinely large and generally counted an improvement.
It is also the only one where storage conditions matter as much as the number of years.
Humidity drives the rate, which is why Guangdong-stored tea at ten years can look like Kunming-stored tea at twenty.
None of this is guaranteed. A badly kept raw cake at fifteen years is still a badly kept raw cake.
A 357 gram cake at 7 grams a session is about 50 sessions, which is a year of weekly drinking.
How to tell
For raw tea, look at the colour of the liquor, which is the fastest indicator of how far along it is.
Young raw is pale yellow and sometimes greenish, and aged raw is orange, then red, then deep brown.
Look at the leaf. Young raw leaf is greenish and tight, and aged leaf is darker and looser.
Smell the broken edge: aged raw should smell clean and slightly sweet, and young raw smells sharp.
Taste for the finish. Young raw dries the mouth, and aged raw leaves sweetness behind.
For ripe tea the equivalent test is cleanliness, since a fishy or sour note is a fault at any age.
Ask for the factory and the recipe number, which matter more than the year for both types.
Ripe tea sold as decades old should be treated with suspicion, since the process dates only to the 1970s.
Compare the same recipe at two different years if a seller has both, which settles it faster than any description.
Price follows the story more than the tea, so taste before you believe anything.
Ten years is where most raw cakes start to be worth drinking, and twenty is near the peak for most palates.
Storage caveat
Storage is not a footnote here, it is most of the value of an old cake.
Raw tea wants air, a stable humidity around 60 to 70 per cent, and no extremes of temperature.
It should not be sealed in plastic, and it should not be kept somewhere that smells of cooking.
The ripe half is more tolerant and will sit in its wrapper for years without much trouble.
Both should be kept off the floor and away from exterior walls, which is where damp arrives.
Check once a year, in the dry season, and otherwise leave everything alone.
Write the year, factory, recipe and price on every cake, ideally on the wrapper itself.
A musty smell means damp got in, and it does not come out with more years or with re-roasting.
Buying old is buying somebody else’s storage history, and most sellers cannot produce one.
Buying young and storing it yourself is slower but verifiable, and for a private buyer it is the better bet.
Sixty to 70 per cent humidity, measured with a hygrometer that costs very little, is the range to hold.