Methods and high visible-light reflective reactive resinous coatings that increase visible light inside a grow house and enhance plant growth therein. A pre-dispersion of a resin, zinc oxide, one or more fillers, and retroreflective microspheres, is mixed with a one-part or two-part reactive coating system to provide a high-reflectance reactive resin coating composition. At least one or more layers of the high-reflectance reactive resin coating composition is coated onto a substrate inside the grow house and allowed to cure. The cured high-reflectance reactive resin layer has a light reflectance increase up to 60% in lumens increasing an amount of visible light inside the grow house to enhance plant growth.