Don't think you can wait until spring to apply your winterizer fertilizer

The term winterizer fertilizer in the marketing world means it is high in nitrogen. The ideal time to fertilize cool season turf with nitrogen is during the Autumn months. It is a good practice to fertilize with a slow release form of nitrogen. During the Autumn months the grass needs fertilizer to build up food storage, carbohydrates and promote root development. Fall fertilizing is essential because with cool season turf you reverse the application in the spring. During the spring months you generally want to apply more potassium and less nitrogen if any at all. Excessive nitrogen in the spring has no benefit for the turfgrass and leads to excessive growth, depletion of reserves and a greater uptake of water weakening the plant before summer stress.