Temperature
Dark tea wants stable room temperature, somewhere between 20 and 30 degrees Celsius. It does not want cold, and it does not want heat spikes, and unlike green tea it should never go in the fridge.
The reason is that dark tea is the only category where change is the goal, and that change is driven by enzymes and microbes that slow down sharply in the cold. A cake kept at 15 degrees will barely move over a decade.
Stability matters more than the number. A steady 25 degree room produces better results than a space that alternates between 15 and 32, because the swings stress the leaf and invite condensation at the cold end.
Warmth is not the enemy it is for green tea. Dark tea is the one category where a consistently warm room is an advantage rather than a problem, provided the humidity is in band and the air is clean.
Humidity
Humidity is the variable that decides everything, and the target is around 60 to 70 percent relative humidity for raw pu-erh and similar compressed teas. Ripe pu-erh and fu brick prefer it somewhat drier, closer to 55 to 65.
Below about 50 percent, transformation nearly stops. The cake is safe but static, and a decade in a dry flat can produce almost no change. Above about 75 percent, you are in mould territory, and the risk is not just a spoiled cake.
Deliberately damp storage does exist and it does speed the change up, but it flattens the tea and carries a real chance of contamination. If a cake smells sour rather than earthy, the humidity went too high for too long.
Light and air
Keep it in the dark. Light is not a major risk for a wrapped cake, but it is for loose dark tea, and there is no upside to storing it in the light.
On air, dark tea is the exception to the seal-everything rule. It wants some exchange, which is why cakes are wrapped in paper rather than plastic and stored in boxes or cabinets rather than vacuum bags. Sealed plastic shuts the process down and, in a humid room, traps moisture against the leaf.
What it cannot tolerate is odour. Dark tea will absorb whatever it is stored beside and keep it for years, so keep cakes away from spices, coffee, paint, and anything else with a strong smell. This is not a preference, it is the most common way home storage fails.
The target environment
The target for dark tea is stable room temperature, moderate humidity, darkness, paper wrapping, and a storage space that smells of nothing at all. A closed cabinet in an interior room is close to ideal in most homes.
Put a hygrometer in that space. Dark tea is the one category where the humidity number genuinely changes the outcome over years, and guessing is not good enough when the gap between good and ruined is about ten percentage points.
Then leave it. Check cakes once or twice a year, press them, smell them, and put them back. Opening them monthly does nothing except expose them to swings.
One check that is specific to dark tea and worth doing every time: press the cake gently with your thumb. A healthy cake feels firm and dry. A cake that feels spongy, or smells sour rather than earthy, has taken up too much water and needs to be moved somewhere drier at once.
Be equally sceptical of the opposite. A cake stored for years in a room below 45 percent will look pristine and taste almost unchanged. That is not a success, it is a cake that has been in storage rather than in progress.
If your home is dry and you want the tea to actually develop, the honest options are a humidified cabinet, a slightly damper room such as a cellar if you have one, or accepting a much longer timeline. All three are better than pretending the room is fine.
Finally, keep the paper wrapper and keep cakes together rather than isolated. A box of cakes buffers itself against swings in a way a single cake on a shelf does not, and it costs nothing to store them as a group.