Tea is an agricultural product sold as a consistent one
Everything upstream of the factory varies year to year: rainfall totals and timing, temperature through dormancy and the first growth, cloud cover, the date the season starts, pest pressure, and how much of the crop the picker takes in a given round. Those variables move both yield and character, and they move them by enough to be obvious in the cup for single-origin tea. A cold late spring delays a first flush and concentrates it; a wet one dilutes it. This is unremarkable in wine and surprises people constantly in tea, because tea is mostly sold in a form that hides it.
Blending exists precisely to remove this
A large blended tea is assembled from many origins and lots to hit a house standard, tasted against a reference, and adjusted continuously as inputs change. The point of the exercise is that the consumer never notices the agriculture. That is a genuine craft and a genuine service, and it is the reason a supermarket breakfast blend tastes the same in March and October. It is also why a drinker moving from blends to single-origin tea meets year-to-year variation as a shock: they have been protected from it for years.
Where the variation is largest
TeaHQ's own reading of well-attested general knowledge, with no single source behind it.
SINGLE-FLUSH, SINGLE-GARDEN TEAS from districts with a sharp season. Darjeeling first flush is the extreme case: a short window, a cold-dependent character, and a price that follows the year. SEASONAL SPECIALITIES. Shincha and pre-Qingming green teas are defined by earliness, so a warm or cold spring moves both the date and the character. TEAS WITH A BIOLOGICAL DEPENDENCY. Where the character depends on something living — the leafhopper activity behind the honeyed character of certain oolongs and darjeelings — variation is not merely large, it is the whole product. A year without the insect is a different tea. WHERE IT IS SMALLEST: year-round equatorial production, CTC manufacture, heavily roasted teas where the roast dominates, and anything blended.
Is it a fault?
Not if the tea is sold as a harvest. It is the reason harvest dates are printed on good single-origin tea and the reason experienced buyers ask about the year before they ask about anything else. It IS a fault if the product is sold as consistent and is not. A blend that has drifted is a quality-control failure; a garden tea that differs between years is the product working as intended. The practical consequence for a buyer: if you find a single-origin tea you like, buy enough of that harvest rather than assuming next year's will match, and expect a good vendor to tell you when a year is unusual rather than pretending it is not.
Telling a bad year from a badly kept tea
The two produce different symptoms and are easy to confuse. A DIFFERENT YEAR tastes different but tastes ALIVE — the aroma is present, the structure is there, it is simply not the tea you remember. A STALE TEA tastes flat rather than different. Aroma is the first thing to go, so the cup smells of little and the flavour reads as hollow or papery regardless of how it is brewed. If a familiar tea has lost its smell, the problem is storage or age. If it smells fine and reads differently, the problem is the weather, and it is not a problem.