The four rules
Four rules cover it: cool, dry, dark, and away from smells. For red tea there is a fifth that quietly matters more than any of them, and it is not on the usual list: away from steam.
Red tea is fully oxidized, so it is the most forgiving category here. It rarely moulds and it does not need humidity for anything. What it loses is aroma, and aroma is what the rules are protecting.
The order of importance runs dry first, then sealed, then dark, then cool. Notice that sealed is doing most of the work, because a red tea in a loose-lidded caddy will flatten within weeks no matter where you put it.
The target is simple: around 20 degrees, below 50 percent humidity, in a genuinely airtight opaque tin, in a cupboard that is not in the kitchen.
Why each rule exists
Dry matters because red tea is rolled rather than pressed, which gives it a lot of exposed surface. With surface comes both aroma loss and moisture pickup, and the two failures feel different but end in the same flat cup.
Sealed matters for the same reason. Volatile aromatic compounds leave through any gap, and the gaps in a decorative tin or a folded bag are much larger than they look.
Dark matters, though less than for green or yellow tea. Light thins the liquor and fades the leaf, but red tea has more colour to lose before it shows.
Steam is the one that gets missed. A tin kept beside a kettle or above a hob pulls in moisture every time someone boils water, and over a few months that is enough to make red tea taste stale and slightly sour.
Apply it to Red tea
Applied to red tea, the container is the whole job. An opaque tin with a gasket lid, and nothing less. A clip on a bag is not a seal, and a caddy that came free with the tea usually is not either.
Buy in 100 to 250 gram lots and split larger purchases into two or three tins on the day you get them. Open one at a time.
Keep the tin in a cool interior cupboard, at floor level if you can, and well away from the kettle and the oven. If the kitchen is your only option, use a cupboard on the far side of the room.
A food-grade silica sachet is a cheap addition if you live somewhere damp. Most change colour when saturated, and they can be dried in an oven and used again.
Make it a habit
The habit that makes the difference is dating the tin. Red tea does not announce its decline, and a tin without a date gets found two years later by someone who assumes it was fine.
Write the date you opened it, not the date you bought it, then rotate: newest at the back, oldest at the front, finish what you start.
Check every three or four months by smelling the dry leaf. Sweet and malty is right. Nothing at all means the aroma has gone, and the tea will brew flat.
Flat red tea is still perfectly usable. Brew it stronger, ice it, or use it as a chai base. There is no safety question, only a loss of character that no storage decision can undo.
Spot trouble early
Trouble with red tea shows up as dullness long before it shows up as spoilage. The first sign is a smell of nothing much, followed by leaf that has gone soft rather than brittle.
Soft leaf means the seal has failed and moisture has got in. Replace the tin, move the tea, and use it quickly, because it will not improve.
Sour is the second sign, and it means the moisture has been there a while. At that point the tea is not worth drinking, and no amount of drying will bring it back.
Mould is rare in red tea, but it happens in a damp cupboard. Any visible growth or a musty smell means the tea goes, not gets trimmed.
The good news is that all three signs appear late and slowly. A red tea checked every few months will never surprise you, which is more than most categories can claim.