Seems rather late for that location but what do I know... I'm used to warm season grass in Texas so it may not apply to cold season grass.

Miloganite requires microbiology activity and it is usually slowed down significantly by cold weather like Chicago...

That being said... I often use Miloganite during the summer but not other times...

Apply the winterizer fertilizer after the grass stops growing but before the ground freezes. See if you can find urea (46-0-0) from a feed store. You would use 2 lb/K sq ft.

+1 BeckyBeck, as usual. The actual date of application will vary--for me, here in Zone 7, it's usually around Thanksgiving. South of here, it walks into December.

For portions of Canada, August is the more likely date, and I believe for Chicago you freeze over in late July sometime. :-)

Milo's great. I love Milo and other organics. But it doesn't decay off fast enough (or at all) when it gets cold enough. For winterization, the window isn't small, but it's not all that wide, either.

It's the one time of year that synthetics make the most sense. Urea's great, but a bit nitrogen dense--a mistake can have serious consequences that won't have time to fix themselves before winter. Fortunately, the colder it gets the harder it is to burn the lawn as well!

I tend to compromise and use a good synthetic of about 29-0-5 or so. I'd go 29-0-0 if I could find it, but everybody seems to put some potassium in the mix. It's harmless, not considered a water pollutant if it runs off, but does no measurable good at that point either.

Be sure to water in the fertilizer, whichever you use. Urea could be hard to find. When I went looking for it last fall it had been sold out from the feed store, and the hardware and big box stores don't carry it. If you use a synthetic, look for one that has mostly fast release nitrogen.

This is great advice. Thanks everyone.

Par Ex with IBDU is another good synthetic choice for early fall use.

Nitrogen fertilization in Fall for cool-season grasses is really divided into three periods - I call them Early Fall, The Pause, and Winterization. Early Fall starts as early as mid-August and involves frequent (like every week) applications of moderate amounts of Nitrogen in its fast-release form, or calculated amounts of Milorganite/slow-release Nitrogen. It goes up until roughly the first frost or 3-4 weeks before ground freeze. Then is "The Pause", in which no Nitrogen is applied -- this allows the lawn to go to sleep normally, and avoids forced-growth. When all growth has completely stopped, a fast-release Nitrogen source is applied for Winterization and is stored in the roots for Spring. Slow-Release Nitrogen shouldn't be used for winterizing.