long-day

[ lawng-dey, long- ]
/ ˈlɔŋˈdeɪ, ˈlɒŋ- /

adjective Botany.

requiring a long photoperiod in order to flower.

Origin of long-day

First recorded in 1915–20
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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British Dictionary definitions for long-day

long-day


adjective

(of certain plants) able to mature and flower only if exposed to long periods of daylight (more than 12 hours), each followed by a shorter period of darknessCompare short-day
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012