Please tell me the difference between winterizer and spring fertilizer.
In cool-season grass maintenance, the basic difference between the fertilizers recommended for spring fertilization and that recommended for application in the fall to prepare the grass for winter is the formulation of the nitrogen. For the spring fertilizer we recommend a 'slow release' formulation which means that the fertilizer contains both nitrogen that is immediately available to the grass and some that will break-down and release over an extended period of time. In the most common of the fertilizers this slow release is brought about by the encapsulation of some of the nitrogen in a coating of sulphur.
The fall fertilizer or 'winterizer' has all of its nitrogen in the quick release formulation so that the grass can take advantage of the maximum amount, storing it in its roots for use in the spring, before the temperature or day length causes the grass to go dormant.
“Winterizing Fertilizer” in the south is not without controversy, and not recommended. After frost when turf is not green the only growth is in roots. Thus, available nitrogen is going to be benefit cool season weeds and may stimulate growth that will be detrimental to overall turf health. However, root systems of turf grass may benefit from some potassium, according to the results of a soil test.