Circadian considerations for controlled environment agriculture: rethinking time in indoor horticultural systems

Controlled environment agriculture (CEA) allows horticultural production all year round by precisely controlling environmental inputs, including temperature, light quality, light intensity and photoperiod. Light and temperature are key regulators of the circadian clock, which coordinates plant physiological and metabolic processes with predictable day-night cycles. A shift from reliance on natural environmental inputs towards precision environmental control has fostered the emergence of environmental regimes operating beyond typical diurnal cycles in CEA. This review summarises current evidence on how photocycles and thermocycles influence plant growth, development, and metabolism in CEA systems. It evaluates how dynamic changes in light intensity, spectral quality, and temperature can enhance productivity, reduce energy costs, and maintain circadian entrainment. It highlights strategies that integrate chronobiology with horticultural practices and outlines research priorities needed to optimise diurnal environmental management in CEA. We recommend practices that leverage the circadian clock as a central framework to enhance crop performance under CEA conditions by linking molecular chronobiology with applied horticulture through targeted temporal management strategies.