A setup that actually works
The setup that works for dark tea is the opposite of what works for everything else. Cakes stay in their paper wrappers, go into a cardboard box or a closed cabinet, and are left alone for years.
Sealed plastic, vacuum bags, and airtight tins all share the same problem here. Each one stops the microbial and enzymatic activity the tea is supposed to undergo, and in a damp room the first two also trap water against the leaf. Paper and a box do the opposite.
Keep the wrappers. They buffer the cakes against swings, they let a little air through, and they keep dust and smells off the surface. Discarding them is a common and avoidable mistake.
Store cakes together rather than separately. A box of cakes holds a more stable microclimate than a single cake on a shelf, and it costs nothing to group them.
Where to put it
The best place is a closed cabinet in an interior room, away from the kitchen and away from anywhere with a smell. A spare-room wardrobe is close to ideal in most homes.
The place must not smell of anything. This is not a preference. Dark tea will absorb odours over years and keep them, and there is no way to wash a compressed cake. Paint, fuel, spices, coffee, and cleaning products are all fatal.
A cool cellar is fine if it is dry and clean. A garage is usually not, because of fuel, paint, and damp concrete.
Avoid the fridge and avoid heat. Cold stops the process entirely, and sustained heat above about 35 degrees pushes it into the wrong kind of fast.
Mistakes to skip
The most common mistake is sealing cakes in plastic. It comes from good instincts about keeping tea fresh, and for every other category it would be right. For dark tea it stops the thing you are trying to do.
The second is storing cakes in the kitchen. Cooking smells get into compressed tea over years, and because the change is slow, people rarely notice the cause until the tea tastes wrong.
The third is over-handling. Pressing, unwrapping, and rewrapping a cake every month does nothing except expose it to swings and smells.
And do not try to speed things up by adding water or humidity directly to the leaf. Artificial wet storage is how cakes are ruined commercially, and it is no safer at home.
Check in often
Check dark tea twice a year, in spring and autumn. That is often enough, and more frequent handling does more harm than good.
Smell first. Clean and earthy is right, with no sour note and no damp, cellar-like edge. Sour means the humidity has been too high, and it is worth moving the tea at once.
Then press the cake with your thumb. Firm and dry is right. Spongy means water has got in, and a cake that has gone soft is at real risk of mould.
Look at the surface too. The white or pale specks inside a fu brick are normal fermentation. Fuzzy coloured growth on the outside is not, and that cake should be discarded rather than saved.
Add a hygrometer to the cabinet. For dark tea this is not optional in the way it is for other categories, because the difference between a cake that develops and a cake that moulds is about ten percentage points of humidity.
If the reading sits below 50 percent for most of the year, accept that this is storage rather than ageing. The tea will keep perfectly well, and it will barely change. That is a legitimate outcome, but it should be a decision, not a surprise.
If it sits above 75 percent, act immediately. Move the cakes somewhere drier, increase ventilation, and check them monthly until the reading is back in the band.
One last thing worth doing: keep a simple list of what you own and when you bought it. With cakes that will not be drunk for a decade, memory is not a system, and a list takes five minutes to start.
The best home setup for dark tea is boring on purpose: a dark box, a stable room, no smells, and years of being left alone.