Wine · Terminology

Ripening

The final run to harvest — sugar up, acid down, tannins and flavours developing.

Ripening is the final stretch of the growing season, from véraison to harvest, in which the grape becomes something worth fermenting. Four things change at once: sugar rises, acidity falls, tannins soften, and aroma compounds develop in the skin.

They do not move at the same speed, and that is the whole problem. A grower can easily have enough sugar for 14% alcohol while the tannins are still green — a mismatch that decides both the picking date and the style of the wine.

In practice

  • Sugar ripeness is measured directly (°Brix, Baumé, Oechsle) and predicts potential alcohol.
  • Phenolic (physiological) ripeness — soft tannins, brown pips, developed flavour — is judged by tasting berries in the vineyard.
  • Warm regions reach sugar ripeness early and risk losing acidity; cool regions ripen slowly and risk never getting there.
  • Canopy management, water and crop level are the grower's levers.

Where you'll meet it

  • The sunlight and heat guides, which explain the drivers.
  • Every debate about rising alcohol levels in modern wine.
  • Late harvest styles, which push ripening past its normal end point.

The picking decision

Harvest date is the most consequential call of the year, and it balances four readings:

Reading Measured by Says
Sugar Refractometer, must weight Potential alcohol
Acidity Titratable acidity and pH Freshness, microbial stability
Phenolics Tasting skins and pips Tannin quality, colour, flavour
Weather The forecast Whether waiting is even an option

Rain before harvest dilutes and invites rot; a heat spike can add a degree of potential alcohol in days. Many "difficult vintage" stories are really stories about picking in the one dry window available.

Cool climate versus warm climate

  • Cool: long, slow ripening; aromatics and acidity retained; risk is under-ripeness, green tannin, thin body.
  • Warm: fast ripening; ripe tannin and generous fruit; risk is high alcohol, low acid, jammy character, and flabby wines.
  • The prized sites in warm regions are the ones that slow ripening down — altitude, sea breezes, north-facing slopes, cool nights.

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