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    Seasons

    The vine's year

    A vine's year runs from winter dormancy through budbreak, flowering and véraison to harvest and leaf fall. Researchers record these stages with the BBCH scale for grapevine, two-digit codes such as 00 for dormancy and 97 for the end of leaf fall.2 Heat sums for the vine are counted above a base of 10 °C over the growing season, April to October in the Northern Hemisphere.7 For the Huglin heliothermal index the window is six months: 1 April to 30 September in the Northern Hemisphere and 1 October to 31 March in the Southern.9 Across European sites and varieties, phenology has responded to recent warming by 3 to 6 days per 1 °C, with the largest shifts at véraison and harvest.7

    JanFebMarAprMayJunJulAugSepOctNovDec
    Northern Hemisphere months. In the Southern Hemisphere the cycle is shifted by about six months.

    1. BBCH 00 · Dec – Mar

      Dormancy

      From leaf fall until growth starts in spring the vine is dormant and consists entirely of woody tissue; roots can keep growing unless the soil is too cold.1 BBCH 00 describes the winter buds, pointed to rounded, with their scales more or less closed.2

    2. BBCH 07 · Apr – May

      Budbreak

      As spring warms, stored starch is converted to sugar and sap begins to move in the vine.1 BBCH 07 is the beginning of bud burst, when green shoot tips are just visible.2,3 In a reference vineyard in the Rheingau, Riesling budbreak averaged 1 May over 1961–1990.4

    3. BBCH 11–19 · Apr – May

      Shoot growth

      New shoots grow very rapidly for several weeks in the absence of stress, and the flower clusters soon appear, usually opposite the third and fourth leaves.1 The BBCH scale counts leaves from 11, first leaf unfolded, to 19, nine or more leaves, and marks inflorescences clearly visible at 53.2

    4. BBCH 65 · May – Jun

      Flowering

      BBCH 65 is full flowering, when half of the flowerhoods (caps) have fallen.2 Flowering can last a day or two in warm, dry weather or as long as a month in very cool, wet weather.1 In the Rheingau reference vineyard, Riesling began to flower on 21 June on average over 1961–1990.4

    5. BBCH 71 · Jun

      Fruit set

      At BBCH 71, fruit set, young fruits begin to swell and the remains of the flowers are lost.2 The new berries develop rapidly, and once they are well formed cell division largely ceases.1

    6. BBCH 81–85 · Jul – Aug

      Véraison

      Véraison begins about five to seven weeks after fruit set: the berries expand further, soften and begin to accumulate sugar.1 BBCH 81 marks the start of ripening, when berries begin to develop their variety's colour.2 French phenology protocols record véraison at BBCH 85, when half of the berries are soft to the touch, a criterion that works for white and red varieties alike.3

    7. BBCH 85–89 · Aug – Sep

      Ripening

      Over the next four to six weeks sugar, pigments and other flavour compounds increase in the fruit while organic acids decrease.1 Acid breakdown in the berries depends strongly on temperature: the warmer the nights in late summer and autumn, the more acid is lost through respiration.4

    8. BBCH 89 · Aug – Oct

      Harvest

      BBCH 89 means berries ripe for harvest.2 In Champagne the harvest runs from mid-August onwards, and its date is set when the balance between acidity and maturity is predicted to be right, so it is never the same from one year to the next.5

    9. BBCH 93–97 · Oct – Nov

      Leaf fall

      After harvest the leaves keep photosynthesising until frost if it is warm enough; after leaf fall the vine goes on acclimating to cold but stores no more carbohydrate.1 The BBCH scale marks the beginning of leaf fall at 93 and its end at 97.2

    Heat ladder

    How warm is a wine region? A simple measure is the average temperature of the growing season, April to October in the Northern Hemisphere and October to April in the Southern.6 Gregory Jones and colleagues group regions into cool (13–15 °C), intermediate (15–17 °C), warm (17–19 °C) and hot (19–24 °C) climates; the values here come from their analysis of 0.5° climate grids for 1950–1999, not from single stations.6 On this scale Pinot Noir is grown where the season averages roughly 14–16 °C and Cabernet Sauvignon roughly 16.5–19.5 °C.7 The Napa Valley value is the median for the whole AVA from a separate study based on 1971–2000 data.8 The Huglin heliothermal index tells a similar story: in the worldwide classification of Tonietto and Carbonneau, Reims in Champagne is very cool, Bordeaux temperate and Jerez de la Frontera in Jerez-Xérès-Sherry warm.9

    cool · 13–15 °Cintermediate · 15–17 °Cwarm · 17–19 °Chot · 19–24 °C13 °C14 °C15 °C16 °C17 °C18 °C19 °C20 °CMosel13.0 °CAlsace13.1 °CChampagne14.5 °CBordeaux16.5 °CRioja16.7 °CCôte-Rôtie and Hermitage17.6 °CBarolo17.8 °CNapa Valley18.8 °CChianti Classico18.8 °CBarossa Valley19.9 °CPinot Noir 14.0–16.0 °CCabernet Sauvignon 16.5–19.5 °C
    Growing season average temperature (Apr–Oct NH, Oct–Apr SH), 1950–1999. 678

    Sources

    1. Annual Cycle of the Grapevine (William Nail, Connecticut Agricultural Experiment Station; reviewed by W. Shoemaker and E. Stafne). eXtension Grapes (Cooperative Extension). level 4
    2. Growth stages of mono- and dicotyledonous plants. BBCH Monograph (ed. U. Meier), section 1.3.17: Phenological growth stages and BBCH-identification keys of grapevine (Vitis vinifera L. ssp. vinifera), Lorenz et al.. Julius Kühn-Institut (JKI), Quedlinburg, 2018. level 4
    3. Measuring the phenology to more effectively manage the vineyard (Destrac-Irvine, Barbeau, de Resseguier, Dufourcq, Dumas, Garcia de Cortazar-Atauri, Ojeda, Saurin, van Leeuwen, Duchêne). IVES Technical Reviews (DOI 10.20870/IVES-TR.2019.2586), 2019. level 4
    4. Klimafolgenmonitoring Hessen, Indikator-Kennblatt: Weinbau - Reifeentwicklung und Weininhaltsstoffe. Hessisches Landesamt für Naturschutz, Umwelt und Geologie (HLNUG); data RP Darmstadt, Dezernat Weinbau Eltville, 2017. level 4
    5. Harvesting. Comité Champagne. level 4
    6. Climate and Wine: Quality Issues in a Warmer World (G.V. Jones, M.A. White, O.R. Cooper, K. Storchmann); manuscript summarising the Jones et al. analysis of 27 wine regions, 1950–1999. Southern Oregon University / author's site climateofwine.com. level 4
    7. Climate change and the global wine industry (G.V. Jones), Proceedings of the Thirteenth Australian Wine Industry Technical Conference. Southern Oregon University / author's site climateofwine.com. level 4
    8. Updated analysis of climate-viticulture structure and suitability in the western United States (G. Jones, A. Duff, A. Hall). Southern Oregon University / author's site climateofwine.com. level 4
    9. A multicriteria climatic classification system for grape-growing regions worldwide (J. Tonietto, A. Carbonneau), Agricultural and Forest Meteorology 124: 81–97. Agricultural and Forest Meteorology (Elsevier); PDF via Embrapa Alice repository, 2004. level 3