Growing season
Growing season refers to the annual period during which grapevines actively grow, develop and ripen fruit, extending from budburst in spring to harvest in late summer or autumn. In viticulture, the growing season is a critical determinant of grape composition, wine style and regional suitability, as it governs the interaction between climate, vine physiology and fruit maturation.[1]
Definition and scope
In a viticultural context, the growing season is typically defined as the interval between budburst and harvest. During this period, the vine progresses through a series of phenological stages, including flowering, fruit set, véraison and ripening. The duration and thermal characteristics of the growing season strongly influence sugar accumulation, acid retention, flavour development and tannin maturity in grapes.[2]
While calendar dates vary widely by region, variety and vintage, the functional growing season is more accurately described in terms of temperature (climate), sunlight and water availability than by fixed dates.
Phenology and vine development
Grapevine phenology follows a sequential pattern regulated primarily by temperature and day length. Budburst occurs once a threshold of accumulated heat is reached, followed by rapid shoot growth and leaf development. Flowering and fruit set typically take place in late spring or early summer, with véraison marking the onset of ripening as berries soften and change colour.[3]
The ripening phase is particularly sensitive to growing-season conditions, as it determines the balance between sugars, acids, phenolics and aroma precursors.
Climate and length of growing season
The length and quality of the growing season vary significantly between wine regions. Cool-climate regions are characterised by short growing seasons with moderate heat accumulation, favouring high acidity and lower potential alcohol, while warm-climate regions experience longer seasons that promote fuller ripeness and higher sugar levels.[4]
Heat summation metrics, such as growing degree days, are commonly used to compare growing seasons across regions and vintages, providing a quantitative framework for assessing varietal suitability and ripening potential.
Sunlight and canopy interaction
Sunlight availability during the growing season plays a crucial role in photosynthesis, flavour development and phenolic maturity. Canopy architecture and leaf area influence how effectively vines intercept light, affecting both fruit exposure and internal vine balance.[5]
Excessive shading can delay ripening and enhance herbaceous characters, while excessive exposure may lead to sunburn, loss of acidity and aromatic degradation.
Water availability
Water supply during the growing season influences vine vigour, berry size and ripening dynamics. Moderate water stress is often desirable during ripening, as it can limit excessive vegetative growth and enhance concentration, whereas severe drought can halt photosynthesis and impair fruit development.[6]
Management of water during the growing season is therefore a key viticultural tool in both irrigated and dry-farmed vineyards.
Climate change implications
Climate change has altered growing season dynamics in many wine regions, generally advancing phenological stages and shortening the interval between véraison and harvest. Rising temperatures have expanded viticultural potential into cooler regions while increasing heat stress risks in traditionally warm areas.[7]
These shifts have significant implications for variety selection, site choice and long-term regional identity.[8]
See also
References
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015, ISBN 978-0198705383.
- ↑ Keller, The Science of Grapevines, Academic Press, 2015, ISBN 978-0124199873.
- ↑ Jackson, Wine Science, Academic Press, 2020, ISBN 978-0128161180.
- ↑ Gladstones, Viticulture and Environment, Winetitles, 1992, ISBN 978-1875130101.
- ↑ Smart & Robinson, Sunlight into Wine, Winetitles, 1991, ISBN 978-1875130033.
- ↑ Keller, The Science of Grapevines, Academic Press, 2015, ISBN 978-0124199873.
- ↑ Jones et al., Climate Change and Global Wine Quality, Wiley, 2012, ISBN 978-1118450048.
- ↑ OIV, “Vine phenology and climate”.