Effects of White LED Correlated Color Temperature on Growth, Flowering, Physiology, and Visual Perception of Spathiphyllum wallisii in Indoor Living Walls

Living wall systems are increasingly used in indoor environments as elements of biophilic design; however, plant growth in these systems relies almost entirely on artificial lighting. While light-emitting diode (LED) technology offers flexible spectral properties, limited information is available on how commercially available white LEDs with different correlated color temperatures (CCTs) affect plant performance in indoor vertical greenery systems. The present study evaluated the effects of three white LED lamps differing in CCT, specifically warm-white (2700 K), neutral-white (4000 K), and cool-white (6500 K), on the growth, flowering, physiological performance, and visual perception of Spathiphyllum wallisii Regel cultivated in an indoor living wall system under exclusively artificial lighting. Plants were grown for eight months under a 12 h photoperiod, and growth parameters, flowering, SPAD index, photosystem II efficiency (Fv/Fm), and biomass accumulation were assessed. In addition, a questionnaire survey evaluated visual preferences under the different lighting conditions. Plant growth parameters, flowering, and physiological performance were largely unaffected by CCT, indicating that S. wallisii can adapt to a wide range of white LED spectra under low-irradiance conditions (~16–18 μmol m−2 s−1). However, cool-white lighting was associated with slightly higher canopy coverage and aboveground biomass compared to other treatments, although overall differences among CCTs were relatively limited. In contrast, survey results indicated a clear preference for neutral-white lighting, which was most frequently perceived as providing the most natural plant appearance and the most suitable illumination for indoor living walls. These findings suggest that neutral-white LEDs may provide a suitable balance between maintaining satisfactory plant growth and achieving favorable visual perception in indoor greenery installations.