I used commercial garam masala for about ten years without thinking about it. Then I made my own once, out of curiosity, and the two tasted so different that I went and read the label on the shop one properly.
It was mostly coriander and cumin. Which is not wrong exactly, and it is a long way from what the name implies.
What is actually in the jar
Commercial blends are optimised for cost and shelf stability, which pushes them in predictable directions.
The cheap spices dominate by volume. Coriander seed is inexpensive and mild, so it makes up the bulk. Cumin similarly.
The expensive ones — cardamom, cloves, mace, cinnamon — appear in small quantities because they are what drives the cost.
And everything is pre-ground, which is the bigger issue, because ground spices lose their volatile aromatics quickly. A jar that has been on a shelf for a year is substantially weaker than it was, in the specific compounds that make it interesting.
The difference when you grind fresh
I was not expecting it to be as noticeable as it was.
Whole spices, toasted briefly and ground, produce something with a top note that pre-ground blends simply do not have. The difference is most obvious with cumin and cardamom, and least obvious with turmeric and chilli, which are more about colour and heat than aromatics.
The practical consequence is that you use less. A teaspoon of freshly ground blend does more than two teaspoons of the old jar, which partly offsets the effort.
The effort, honestly
It is not nothing. Toasting and grinding a batch takes about fifteen minutes.
What made it sustainable was making small quantities more often rather than large quantities occasionally. A jar that lasts a month stays good. A jar that lasts a year has gone stale by month three, which puts you back where you started.
A cheap electric grinder, kept only for spices, does the work. A stone mortar is better for small amounts and for anything you want coarse, and slower.
I do not grind everything fresh. Turmeric, chilli powder and coriander I buy ground, because the loss is smaller and the volume is higher. The aromatic ones I do myself.
Blends are regional and the jar is not
The thing that changed my cooking most was realising that garam masala is not one thing.
The composition varies enormously by region and by household. Some are warm and sweet, heavy on cinnamon and cardamom. Some are darker and more pungent. Some include ingredients that others would consider wrong.
A single commercial jar has flattened all of that into one product, which is then used for every dish regardless of what the dish wants.
Once I started making my own I ended up with three. A warm one, a darker one, and a very simple one that is mostly cumin and pepper. Using the right one for the dish is a bigger improvement than freshness alone.
When it goes in
A related thing I had wrong.
Garam masala is generally a finishing spice, added near the end or off the heat, because its aromatics are volatile and prolonged cooking drives them off.
I had been adding it at the start with everything else, which is where the base spices go. That is the correct place for coriander, turmeric and chilli, which benefit from cooking in fat, and the wrong place for the aromatic blend.
Splitting them — base spices early, aromatic blend at the end — produced a noticeable improvement with no change in ingredients at all.
What I would tell someone
Do not throw out your jars. Use them for the base spices where it matters less.
Buy whole cumin, coriander, cardamom, cloves and a cinnamon stick. Toast a small quantity, grind it, and taste it next to your shop blend. That comparison is the whole argument and it takes twenty minutes.
If the difference does not seem worth it to you, that is a legitimate conclusion and you have lost twenty minutes.
For me it was the single biggest improvement in flavour I have made, and I resisted it for a decade because it sounded like the sort of thing people say to seem serious about cooking.
Storing what you make
Since the whole argument is about freshness, storage is not a detail.
Ground spices should be in something airtight, opaque or kept in a dark cupboard, and away from the stove. The rack of jars beside the hob is the worst possible place, because heat drives off exactly the aromatics you ground for.
Whole spices keep far longer than ground, which is the practical argument for buying whole and grinding small amounts.
I keep whole spices in larger jars at the back and one small jar of each ground blend in use. When the small jar is empty I grind another, which takes ten minutes and happens every few weeks rather than being a project.