Colored Shade Nets Affect Growth but Not Flowering of Four Greenhouse-grown Potted Ornamental Species

The color of horticultural shade nets is known to influence crop growth and quality because of variations in the amount and quality of light. Four ornamental plant species (celosia, begonia, gerbera, and fountain grass) were grown under aluminet, pearl, and red shade nets plus black as the control at 50% shade intensity for 8 weeks. Black had the least transmittance (-10% to 30% of ambient) within the red spectrum (620-750 nm), whereas red had the greatest at -70% to 80%. Aluminet and pearl resulted in a similar reduction in photosynthetic photon flux at -50% to 55% and -55% to 65% of ambient, respectively. Aluminet increased the shoot dry weight for begonia and celosia, whereas no differences among shade nets were seen for gerbera or fountain grass. The chlorophyll concentration was greatest under aluminet for each species except begonia. Shade net color did not affect flower number.