We are fast approaching the date on the calendar when you should treat your lawn with an overwintering fertilizer.
Now, first things first: let’s cover what those numbers on the fertilizer bag stand for. They correspond, respectively, to the percentage of nitrogen, phosphorus and potassium in the fertilizer.
Here’s where you need to be wary of a myth that in order to “overwinter” your lawn with fertilizer to improve hardiness over the winter, you need to apply a fertilizer that is higher in concentration of phosphorus and potassium.
Maybe that’s true if you’re in a more temperate climate, because only warm season grasses benefit from this approach. But it’s certainly not true for our climate here in the Chicago area.
Instead, our cool season grasses, such as bluegrass, require high concentrations of nitrogen to overwinter the turf. To properly overwinter your lawn, my recommendation is that you use fertilizer with a ratio of 25-0-3 or 25-5-5 (remember, that’s for nitrogen, phosphorus and potassium, respectively).
As always, properly read the label and follow the application instructions and rates.