Like a lot of other applicators, I wait until top-growth has stopped in my customer's lawns, before I begin my Winterizer round. I also make sure that my lawns haven't lost their color yet. By timing my Winterizer apps the way I do, I realize that nitrogen that's applied to the lawn when I do this application is stored in the root system of my lawns in the form of starches (carbohydrates). This reserve is then used the following Spring. My question is whether phosphorus, or potassium are of any use to lawns at that time of year when only the root systems in my lawns are active? If P & K are of no use when only the root systems are active, then it would be pointless to apply a fert that contains these two nutrients. I'm sure a lot of applicators (me included) will learn a lot from what some of the more knowledgeable members have to say about this. I'm looking forward to reading any replies.