Its season
Spring is green tea’s season, and the reason is harvest rather than mood.
The first flush is picked from late March through early April across most of China.
Pre Qingming（清明）leaf, cut before the festival that falls around 5 April, is the most prized.
That leaf is young, thin and sweet, and it tastes like the season it came out of.
A second picking runs through April and into May, and it is sturdier and cheaper.
By June the same bushes give leaf that is coarser and better suited to blending.
So the calendar is real: the tea you want in March is not on sale in September.
Stored well, a spring green will still be drinkable at 6 months, though the aroma has gone.
Vacuum packed and kept at 5 °C, it holds most of its freshness to the following spring.
Kept in a warm cupboard, it will be flat by August.
That is the practical reason the season matters, since freshness has a shelf life.
Buy it once a year, in spring, and drink it through the summer.
Anything sold as new spring leaf in November is either stored very well or mislabelled.
Why the season fits
Tea and season are linked by weight and temperature, and green tea sits at the light end.
In hot weather a light, low body cup is what most people actually want.
Brewed at 80 °C and cooled to room temperature, it reads as clean rather than thin.
In cold weather the same cup reads as insubstantial, because there is nothing to warm against.
Aroma is the second link, and it is seasonal in a more literal sense.
The grassy, slightly sweet smell of a young green matches what is growing at the same time.
That is partly cultural, and partly just what the leaf contains.
Amino acids are highest in the earliest flush, and they are what produce the sweet brothy note.
Later pickings carry more catechins, which taste more astringent and less sweet.
So spring is more than tradition, since it is measurably a different material.
Summer brewing suits it too, since iced green tea needs no sugar to be drinkable.
Winter is where the fit breaks down, and a roasted tea will do that job better.
Off-season
Nothing forbids green tea in October, and plenty of people drink it all year.
What changes is what you have to adjust to get the same result.
Raise the water to 85 °C and add a gram of leaf, and a tired spring green wakes up.
Brew it in a smaller vessel so the heat stays where the leaf is.
A 100 ml gaiwan in December behaves better than a 300 ml mug.
Roasted greens are the other answer, since the roast carries into cold weather.
Aged greens exist but are rare, and they taste closer to a light dark tea.
If the cup tastes thin, the problem is usually the water rather than the season.
Water below 70 °C will not extract enough from any leaf.
Cold brew is a summer option and a poor winter one, for obvious reasons.
Serve it hotter and stronger and the off-season gap mostly closes.
Accept that the aroma will not be what it was in April.
Year-round note
Most categories have a style for every kind of weather, and green is no exception.
The variable inside green tea is roast and picking date rather than oxidation.
A pre Qingming（清明）leaf is the spring style, light and sweet.
A later April picking is the everyday style, and it works from May to September.
A pan roasted green is the autumn and winter style, and it has the body to match.
Roasted greens cover December and January comfortably.
Sencha, steamed rather than pan fired, sits in the middle and works most of the year.
Matcha is thicker than any of them, and it is the one that survives a cold morning.
So the season is a guide to which green to reach for, not a gate on the category.
If you keep 3 styles in the cupboard, the calendar stops mattering.
Buy the light one in spring and the roasted one in autumn, then drink both across the year.
A tea stored badly in April will be worse in October than a fresh one bought then.
Storage decides whether any of this works: cool, dark, sealed and dry.