Your lawn’s nutritional needs change during the fall in preparation for the cold weather ahead. Winterizing fertilizers are high in potassium. Potassium is a very important nutrient in overall plant health. Winterizing fertilizers work at the cellular level to strengthen and harden plants from top to bottom, making them more tolerant of cold and stress. Potassium also helps a plant absorb other nutrients, making Winterizing one of the many important services we provide.