In the world, the seedling planting method comes into prominence to save on irrigation water due to climatic changes, to increase the yield per unit area with lengthy vegetation varieties, and to reduce chemical input in pest and disease control. The basic element of being successful in transplanting paddy production is to grow healthy and quality seedlings. For machine transplanting, it is necessary to grow in a special viol environment. For paddy seedlings in trays, it is required to prepare special mortars rich in plant nutrients and economical. In this research, four replications were carried out in an unheated polyethylene greenhouse of Ondokuz Mayıs University Agricultural Research and Application Center in 2020 with 20 different mortar media and three paddy varieties (Baldo, Vasco and Tosya Güneşi). To determine the seedling quality, seedling length, seedling stem diameter, leaf number, root length, root number, above ground and root wet weight, above ground, and root dry matter ratio values were examined 21 days after planting. According to the research results, the effect of different medium crosses, cultivars, and environment x cultivar combinations used on the seedling quality characteristics was statistically significant. The results showed that seedling length was 68.39-218.19 mm, seedling stem diameter was 0.97-2.64 mm, number of leaves was 2.0-4.0, root length was 16.95 - 98.35, number of roots was 4.25-10.75, shoot wet weight 5.40-131.55 mg, root wet weight 3.03-104.28, shoot dry weight ratio was 5.95-27.42%, and root dry weight ratio was 1.37-15.13%. The biplot analysis results showed that the Vasco variety had the best quality of seedlings in growth media numbers 13 and 18. The evaluation of growth media's quality, economically and ecologically, showed that growth media number 13 was the best media, and media numbers 18 and 19 could be used as alternatives.