Flowering: Difference between revisions

'''Flowering''' is a key [[Phenology|phenological]] stage in the annual growth cycle of the [[grapevine]], during which the vine’s flowers open and fertilisation occurs. It marks the transition from vegetative growth to reproductive development and plays a decisive role in determining [[yield]] and potential fruit composition in the resulting [[wine]].<ref>Robinson (ed.), ''The Oxford Companion to Wine'', Oxford University Press, 2015, ISBN 9780198705383.</ref>

[[Flowering]] typically occurs several weeks after [[budbreak]], once sufficient heat accumulation has been reached. The exact timing varies according to [[climate]], site conditions and [[grape variety]]. Most cultivated grapevines (''[[Vitis vinifera]]'') have hermaphroditic flowers and are largely self-pollinating.<ref>Mullins, Bouquet & Williams, ''Biology of the Grapevine'', Cambridge University Press, 1992, ISBN 9780521305071.</ref>

The process begins when the protective caps (calyptrae) detach from the flowers, exposing the reproductive organs. Successful pollination and fertilisation lead directly to [[fruit set]].<ref>Keller, ''The Science of Grapevines'', Academic Press, 2015, ISBN 9780124199873.</ref>

Flowering is one of the most weather-sensitive stages of the vine’s annual cycle. Cool temperatures, rain, wind or cloudy conditions can disrupt pollination and fertilisation, increasing the risk of [[coulure]] (poor fruit set) and [[millerandage]] (uneven berry development). Warm, dry and stable conditions are generally considered optimal.<ref>Gladstones, ''Viticulture and Environment'', Winetitles, 1992, ISBN 9781875130101.</ref>

The proportion of flowers that successfully develop into berries determines the number of berries per cluster, a primary component of yield. Poor flowering conditions can reduce yields substantially, while very favourable conditions may lead to large crops that require later intervention through [[green harvesting]] or other yield-management practices.<ref>Ribéreau-Gayon et al., ''Handbook of Enology, Volume 1'', Wiley, 2006, ISBN 9780470010372.</ref>

Variability at flowering is one reason vintage conditions can differ markedly even within the same vineyard or region.<ref>Winkler et al., ''General Viticulture'', University of California Press, 1974, ISBN 9780520025918.</ref>