A forest fire retardant composition contains a retardant compound that includes a potassium salt. The potassium salt may include a potassium salt of an organic acid, a potassium salt of an inorganic acid, or mixtures thereof. The organic acid may include formic acid, acetic acid, propanoic acid, butanoic acid, lactic acid, oxalic acid, malic acid, gluconic acid, tartaric acid, uric acid, malic acid, or citric acid. The inorganic acid may include sulfuric acid, phosphoric acid, carbonic acid, or hydrochloric acid. The composition may be in the form of a dry concentrate, a liquid concentrate, or a final diluted product. The final diluted product is effective in suppressing, retarding, and controlling forest fires while exhibiting corrosion resistance and low toxicity.