Abstract Five media prepared from old peat (OP), white peat (WP) and municipal solid waste compost (MSWC) were used to determine optimum growing media for tomatoes ( Lycopersicum esculentum Mill. cv “Atletico”). The mixtures of substrates used were: OP (65%) + WP (30%) + perlite (5%), OP (65%) + MSWC (30%) + perlite (5%), WP (65%) + OP (30%) + perlite (5%), WP (65%) + MSWC (30%) + perlite (5%), MSWC (65%) + WP (30%) + perlite (5%). Various seedling indices were measured in order to assess the quality of the nursery-produced plant. Nursery-produced tomato seedlings grown in WP (65%) + MSWC (30%) displayed quality indices similar to those recorded for conventional mixtures of old and white peat sphagnum, due to a correct balance between the compost nutrient supply and the porosity and aeration provided by white peat.