Fertilome Winterizer Fertilizer Is The Most Important Feeding Of The Year For Your Lawn. Builds roots, disease resistance and wintering ability. Your lawn will green up earlier in the spring. Use Winterizer in October to November in the upper MidWest. May be used on all types of grasses, trees, ornamentals and evergreens. formula 10-0-14 balance with trace elements. One 20 Lb. bag covers up to 5,000 sq. ft. George says, "If you do nothing else, all year long, at least use Winterizer."