I'm sure morph and the gang can better assist you but in the interim I can share what they told me. You're right, the warming/cooling that's going on makes it tricky and it seems like the "perfect" time is going to be a little late this year. I think Dec 4th was the date approximation I heard. I put mine down last weekend due to my time schedule and morph estimated I'd get about 90% of the benefit.

HTH

Pretty much we just do the best we can as I've seen very few years that featured a gradual and steady drop in temperatures. Yesterday was 61 here. Tomorrow, 45. But temperatures will rebound.

If the grass is still green and growth is at least down to very slow, you're OK to drop at any time. Technically, I could go now, but the best date for me is still around December 4th by the current forecast. After that, it rains and stays warm for a few days, then drops fast.

I thought the ground would drop more slowly than the air temp and I'd have time no matter what. I haven't been home much during daylight this week, so I guess I'll have to see how much, if any, the grass has been growing before the snow hits tomorrow.

It's going to be colder the next few days, but then we have some warmer days coming next week, so I guess I'll just play it by ear.

Thanks for both of your input.

Ear is really the only way we play it. :-) While the soil won't cool down so quickly, the top growth could conceivably be taken out by an extreme cold snap...which would brown it instantly and mean that you couldn't winterize. I've never seen it happen, but it's possible.

I have the mower out today and it's still taking off half an inch of growth in a week--so my lawn, at least, isn't nearing its long winter's nap. The next door neighbors' tri mix is already going brown. So it even differs lawn by lawn...

I got up early this morning, re-checked the weather forecast, and saw that the predicted lows the next few days dropped even more. It's supposed to get down to 12 tomorrow night, although it's snowing hard, so we should still have snow cover to protect the grass.

But since I've never really paid attention to when my grass goes dormant and the effect of the outside temps on that, I decided to go ahead and put it down this morning...in the semi-darkness and while it was lightly snowing. I'm hoping the neighbors were still sleeping, :-) because not only was I fertilizing in the dark and snow, but first I went around and picked up leaves (by hand) that had blown into low spots in the lawn. Those are exactly the spots I want to help fix by overseeding this winter.

Sunday night I dumped 8 bags of chopped leaves onto the lawn so they could get mowed in on Monday. Someone walking by asked if I lived here - apparently, she thought I must be vandalizing the property. Why else would anyone be dumping lawn bags onto the lawn?

Finished covering all my hydrangeas this morning too, put a few extra bags of chopped leaves out of the way, and dumped the rest "out back" in two piles to make leaf mold. The garage is almost clean, so that's a great feeling.

The snow is piling up outside, and even if it wasn't exactly the "right" day to winterize, it feels right today. I'll pay attention to what happens the next couple weeks, and next year I'll know just a little bit more.

Pro tip: you're close enough since the snow is expected to melt off.

My neighbors know me well enough not to be terribly surprised by anything I do. The back neighbor is a little annoying (he's the staring at you out of windows sort), so I do make sure to nibble occasionally out of my spreader when I'm spreading soybean meal.