Poor germination of Stevia rebaudiana Bertoni seeds is a phenomenon with unknown reason and theresearch concerning the improving of germination are still in progress. We investigated the influence oflight-emitting diodes (LEDs) spectra on Stevia seed germination as well as seedling growth and selectedmorphological and biochemical parameters. Blue LED light increased seed germination and affected thedevelopment of the largest number of leaves and roots in 4-week-old Stevia plantlets. It has also the mostfavourable effect on the number and opening of stomata. Red LED light however, significantly increasedthe length of stems and roots, although there was not correlation with the fresh weight (FW). The highestFW of Stevia plantlets achieves under combined red and white LED light at temperature of 20◦C aswell as under white fluorescent light at temperature of 25◦C. Blue LED light also positively affected thecarotenoids concentration, whilst the highest concentration of chlorophyll a and b was found, in plantletsgrown under white fluorescent light. The less favourable effect on the synthesis of all the examinedpigments was exerted by red LED light. The largest amounts of phenolics and soluble sugars accumulatedplantlets growing in the darkness and irradiated blue LED light. In addition, all LEDs affected the activityof antioxidant enzymes. The blue LED light increased the activity of catalase (CAT) and peroxidase (POD),especially at 25◦C. Red LED light significantly increased activity of superoxide dismutase (SOD) whilstfor the activity of CAT and POD opposite effect was observed. The combined red with white LED lightwas the most favourable for the activity of CAT at 25◦C. We conclude that the seed germination and thequality of Stevia plantlets could be improved by controlling light quality.