Effects of Different Light Spectral Compositions on the Growth of ‘Akihime’ Strawberry (Fragaria × ananassa) in an Indoor Vertical Farm

Light spectral composition is an important environmental factor affecting strawberry growth and fruit production in controlled-environment agriculture. This study evaluated the effects of five light-emitting diode (LED) spectra on photosynthetic performance, vegetative growth, flowering, fruit production, and final biomass in ‘Akihime’ strawberry (Fragaria × ananassa). Plants were grown for 31 weeks under LED treatments with different proportions of blue, green, red, and far-red light, while the photosynthetic photon flux density was maintained at 250–300 μmol m−2 s−1. Photosynthetic responses were influenced mainly by developmental stage, although significant treatment × weeks after transplanting interactions were detected for the maximum relative electron transport rate and light saturation point. LE3 (B15.6:G18.7:R49.2:FR16.3) produced greater petiole length and root dry weight than the control. LE2 (B19.2:G30.0:R49.5:FR1.3) showed the earliest observed anthesis, although final flower number and fruit number did not differ among treatments. LE3 and LE4 produced significantly greater mean fruit weight than the control, and LE3 ranked highest in the Best–Worst Method–Technique for Order Preference by Similarity to an Ideal Solution (BWM–TOPSIS) evaluation. These findings suggest that strawberry responses depended on the complete spectral composition rather than on the red-to-blue ratio alone. Stage-specific spectral management may therefore improve the performance of ‘Akihime’ strawberry in indoor vertical farming.