Nutrifield Si-Phi 250ml Mono Silicic Acid and Phosphite Si-Phi is a synthetic blend of potassium silicate (Si) and potassium phosphite (Phi), two plant biostimulants which promote robustness and stress tolerance. Silica supports and strengthens cell walls and promotes tolerance to heat and drought stress. Phosphite functions as a biostimulant, unlike the nutrient source phosphate. Phosphite thereby impacts plant metabolism to promote resilience, growth and yield. Use Si-Phi throughout the entire grow cycle to ensure plants thrive in all environments. Recommended for horticultural and agricultural uses