If you want to winterize, I would not use the fertilizers that are usually sold as winterizers. Instead, I'd use something with a high first number and 0 for the second and third numbers. Apply it after the top growth has stopped, but while the grass is still green.

There are a few fertilizers that are sold as starter fertilizers with crabgrass control. These have a pre-emergent that affects crabgrass but allows lawn seeds to germinate.

I fertilize mid-may after soil has warmed up, late august tto early sept, and mid october and sometimes around thanksgiving.
Don't fertilize when it is hot and humid!

bpgreen,

So use a high nitrogen fertilizer after the growth has stopped? What about the root growth and etc?

And does one have to water after fertilizing after the growth has stopped? Is the rain fine even if it's a few days away?

The old thinking was that you wanted fertilizer with a high percentage of P for the roots going into winter. But recent studies have shown that the more important nutrient is N. The grass will take in the N and since it's not using it to try for leaf growth (and eventually seeds, but we cut before that happens, anyway), it uses it all for storage in the roots.

I think the rain is fine even if it's a few days away.

didn't know that, thanks bpgreen

Professional grass farmers (also known as livestock operators) apply 2/3 to 3/4 of the annual nitrogen in the fall and the other amount in the late spring after the grass has stopped growing. Late spring ends for most of us by Memorial Day.

Hi Dave, long time no see :)

Made some newbie mistakes. Oh well, next year is new year. =)