A setup that actually works
The setup that works for green tea is smaller than most people expect. One or two opaque tins with gasket lids, holding 50 to 100 grams each, kept in the fridge. That is the whole system.
Buy a larger bag if you like, but split it on the day it arrives. Put one tin in the fridge unopened and use the other. When the first runs out, bring the reserve out, let it reach room temperature, and start on it.
The container matters more than the brand. It needs a real seal, it needs to be opaque, and it needs to be dry when you fill it. A tin washed the same morning will put more water into the tea than a year in a fridge would.
If you drink fast and finish a tin within a month, a cool cupboard is fine and the fridge is optional. The fridge is for the tea you are not going to get to quickly, which for most people is most of it.
Where to put it
The best place is the fridge, in the main compartment rather than the door. The door swings, and the temperature swings with it.
The second best place is the coolest interior cupboard in the house, at floor level, against an internal wall. Interior rooms are more stable than rooms with outside walls, and floors are cooler than high shelves because warm air rises.
The worst places are all in the kitchen. Above the oven, beside the kettle, on a windowsill, or in a cupboard that houses the bin. Green tea is the most aroma-sensitive category, and a kitchen offers heat, steam, and smells at the same time.
One more place to avoid: a shelf that gets direct sun for part of the day. Even through an opaque tin, a few hours of daily sun will warm the leaf enough to matter.
Mistakes to skip
The most common mistake is a clear jar on the worktop. It looks right and it is wrong on all three counts: light, air, and heat. If you want to see the leaf, keep a small sample jar for display and store the rest properly.
The second is leaving tea in the bag it came in, folded over. That bag was designed for transport, not storage, and it lets odour and moisture in from the day you open it.
The third is opening the tin constantly. Every opening changes the atmosphere inside. If you brew daily, decant a week’s worth into a small tin and leave the main one shut.
And do not store green tea next to anything with a smell, including tea of another type. A green tea kept beside a roasted oolong will start to taste of the oolong within weeks.
Check in often
Check green tea every couple of months, and always smell before you brew. The dry leaf should smell clean and vegetal, sometimes sweet, sometimes a little grassy.
If it smells flat, or like hay, it has lost its top note and it is on the way out. Drink it quickly or use it for cold brew, where the loss of aroma matters less. If it smells damp or sour, it is finished.
Look at the leaf as well. It should snap when you bend it. If it bends and stays bent, moisture has got in and the seal has failed.
Finally, check the tin itself once a season. Gasket lids degrade, hinges loosen, and a seal that was good last year may not be this year.
One habit that makes all of this easier: keep a note of when you opened each tin. Green tea does not change dramatically, and without a date you will not notice a slow decline until it is well past saving.
If you find a tin you forgot about, brew a cup before you decide anything. Old green tea is not dangerous. It is just dull, and a five minute taste test tells you whether it is worth keeping.
None of this needs to be elaborate. A tin, a date, and a cool dark place will get you most of the way there, and those three things beat any amount of equipment bought later.