Potassium thiosulfate (KTS) is a liquid fertilizer that supplies potassium and sulfur. Potassium thiosulfate is a neutral to basic, chloride-free, clear, liquid solution that can be applied through fertigation alone or in liquid blends with urea solution, urea ammonium nitrate solutions, and 10-34-0. Very dilute potassium thiosulfate can be used as a foliar fertilizer on certain plants, but is known to cause phytotoxicity symptoms under certain conditions and should be used with caution. Potassium thiosulfate is pH sensitive and becomes unstable at pH below 5.5 and above 8.5. The elemental sulfur in thiosulfate will oxidize and generate sulfuric acid that can lower soil and media pH. Greenhouse and nursery managers should use caution when applying potassium thiosulfate to unbuffered soilless media.
