The biggest cause of weak cooking isn't bad technique or cheap spices — it's spices that have been sitting on the shelf for a year. Spices don't spoil the way dairy does, but the volatile oils that give them aroma evaporate fast, especially under heat and light. Store them right and the same jar tastes dramatically better six months in.

The four enemies of aroma

Air — oxidation flattens aroma. Every time you open the jar, the clock ticks faster.
Light — UV breaks down spice pigments and tea polyphenols. Clear glass jars on a window sill is the worst-case scenario.
Heat — accelerates oil evaporation. Stove-top shelves are the second-worst.
Humidity — causes caking in ground spices, mould in whole ones. Above the sink = bad idea.

Shelf-life reality

Manufacturers print "best before 24 months" because it's what Indian food labelling regulations require. Real-world aroma life is much shorter:

Whole spices (cumin, coriander seeds, peppercorns, cardamom, cloves): 12 months at full aroma, 18–24 months edible but flat.
Ground spices: 2–3 months at full aroma, 6 months tolerable. Ground garam masala past 3 months is essentially decoration.
Dried herbs (bay leaf, oregano, kasuri methi): 6 months.
Black tea (Darjeeling, Assam): 12 months sealed, 3 months once opened.
Green tea: 6 months sealed, 1 month once opened.

How to store whole spices

Airtight glass jars, full to the top. Half-empty jars oxidise twice as fast.
Dark, cool cupboard — away from the stove, away from windows. If your kitchen only has lit open shelves, store the back-up stock in a drawer.
If you buy in bulk, keep the main stash sealed in the original pack and refill a small working jar — you'll extend aroma life by months.

How to store ground spices

Same rules as whole spices, with a critical addition: grind in small batches. Ground cumin ground yesterday is a different ingredient from ground cumin ground six months ago. If you're buying pre-ground, buy small packs and replace them quarterly.
Avoid buying giant 500 g ground masala packs unless you're cooking at volume — you'll get maybe 6 weeks of proper aroma out of it.

How to store tea

Opaque, airtight tin — not a glass jar on the counter. Light is especially rough on Darjeeling first flush.
Room temperature, not the fridge. Tea absorbs odours; a fridge full of onions is a disaster.
Store away from strong-smelling spices. Tea shelf ≠ masala shelf.
Once opened, finish black tea within 3 months and green tea within 1 month. Yes, really.

Signs your spices are past it

You rub the spice between your fingers and smell nothing.
The colour has faded visibly compared to a fresh pack.
The ground spice cakes into clumps that don't break easily.
The oil has migrated to the top of the jar (common with whole cloves + peppercorns stored in warm areas).

Practical kitchen setup

If you cook daily and want an evidence-based setup:

One working jar per spice near the stove — small enough to finish in 4–6 weeks.
Main stock in a dark, cool cupboard in the airtight pack it came in.
Tea in an opaque tin, in a different cupboard from spices.
Rotate: when the working jar empties, refill from the main stock, not the other way around.

The reason Thar Blends grinds in small batches and prints the grind date on every pack is exactly this: ground spices are a perishable, and pretending otherwise is how supermarket masalas end up tasting like cardboard. Buy for 8 weeks of cooking at a time, store them right, and the difference is immediate.