Matching circadian rhythms to light-dark cycles increases lettuce yield by 29% in vertical farms without additional energy input.

Most cultivated lettuce varieties have 27 h circadian clocks resulting from domestication-driven selection for delayed bolting yet are grown under standard 24 h light-dark cycles. This creates a fundamental mismatch between plant biology and cultivation practices. According to circadian resonance theory, this misalignment imposes chronic re-entrainment costs that reduce fitness. Here we demonstrate that eliminating this mismatch through circadian resonance, namely aligning environmental cycles with internal rhythms, increases lettuce biomass by 11-29% without additional lighting energy in commercial vertical farming conditions. We grew 20 lettuce accessions with characterized circadian periods (24-28 h) under six light-dark treatments combining two cycle lengths (24 h and 27 h) with three photoperiod regimes. Long-clock varieties (∼27 h) consistently accumulated more biomass under 27 h versus 24 h cycles when the daily light integral remained constant (14.4 mol m-2 d-1). Enhanced yields resulted from extended dark periods (11 h versus 8 h) rather than increased light input, representing a lighting-efficient cultivation strategy. High-energy treatments (18 mol m-2 d-1) achieved maximum biomass but triggered morphological aberrations and increased tipburn, while resonant conditions maintained quality standards. Resonant conditions also restored natural developmental timing, with long-clock varieties showing accelerated bolting that reversed the delayed flowering phenotype observed under 24 h cycles. Importantly, bolting still falls outside the cultivation window. Statistical modelling confirmed significant interactions between the circadian clock and the diel length, establishing circadian resonance as the primary driver of yield improvement. These findings reveal circadian resonance as a transformative strategy for yield enhancement in controlled-environment agriculture, such as vertical farms, achieving significant biomass gains through biological rhythm optimization.