Description of <scp>BBCH</scp> ‐based phenological growth stages of the geophytic aroid <scp> <i>Amorphophallus paeoniifolius</i> </scp> (Araceae)

Abstract Amorphophallus paeoniifolius (elephant foot yam) is a tropical geophytic crop of significant agricultural and ethnobotanical value in Southeast Asia. Despite the relevance of the species, the life cycle and phenology of A. paeoniifolius remain poorly documented. This study presents the first comprehensive characterization of its phenological development using an extended Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale. Fieldwork was conducted from June 2024 to May 2025 in Dimiao, Bohol, Philippines. A species‐specific BBCH scale coding was developed, capturing key phenological stages: corm dormancy, leaf emergence, inflorescence development, anthesis, fruiting and senescence. A bimodal life cycle synchronized with the Northeast and Southwest Monsoon systems was observed, with a dormancy phase from October to May and an active reproductive–vegetative phase from April to September, primarily regulated by rainfall and rising temperatures. Observations support a resource allocation trade‐off, where corms alternate between reproductive and vegetative investment in response to environmental cues, particularly the onset of the Southwest Monsoon with rising precipitation, consistently high relative humidity and increasing temperatures that signal the shift from dormancy to active growth. Within this framework, the BBCH codes developed encompass dormancy (00), leaf development (10–19), pseudostem elongation (31–39), inflorescence and fruit development (51–59, 60–69, 71–79, 81–89) and senescence with return to dormancy (91–97). This baseline phenological model lays the groundwork for future long‐term ecological studies for sustainable cultivation and conservation of A. paeoniifolius under changing climatic conditions.