Sphingomonas panaciterrae (PB20) significantly improved spinach growth and nutritional profile. Seed priming increased plant height by 65.65%, fresh weight by 37.41%, and vitamin C by 94.6%. Foliar application boosted nutrient content, including phosphorus in roots (78.48%) and magnesium, iron, and zinc in shoots. PB20 is a promising biofertilizer.