Light qualities are considered to affect many plant physiological processes during growth and development. To investigate how light qualities make an influence on tomato seedlings under greenhouse conditions, the growth and morphological parameters of tomato seedlings (Fortizia F1RC hybrid) were studied under three supplemental light irradiations such as light-emitting diodes with nanoparticle coating (LED 1—Red light-emitting diodes); Blue, Green, Yellow, Red light-emitting diodes (LED 2), and traditional high-pressure sodium (HPS) lamps with different photosynthetic photon flux density and the same irradiation time for 33 days. Morphological appearances of three groups of tomato seedlings were different between light treatments, that is, the plants under LED-1 and LED-2 were shorter than those under HPS, while stem diameter, leaf area, dry and fresh weights, and health indices of tomato seedlings grown under alternative light sources were higher than of those cultivated under traditional HPS lights. However, the higher plant height was in plants containing traditional high-pressure sodium lamps treatment. Photosynthetic pigments were shown to have a significant difference under respective light irradiations of LEDs. The levels of photosynthetic pigments were higher in the leaves of seedlings under LED 1 and LED 2, and lower in those that underwent HPS control treatment. Based on the data of morphological and statistical analysis, LEDs with nanoparticle coating proved to be beneficial factors for the growth of tomato seedlings under greenhouse conditions.