Well, I finally did it...overseeded the 10-month-old TTPR/KBG lawn with TTTF and KBG...and it worked! So it can be done...but read on to find out how I did it...I was quite careful due to what people on here had told me about the PR messing with the germination of other seed due to allelopathy. I did this a little over a month ago now. I actually prefer the lawn consisting of a mixture of these three species, guess I'm odd since no one else here seems to like that three-way mix). We're at ~4.5 weeks now. The existing PR thankfully did not prevent or delay germination of the new seed. The TTTF started to come up within 6 days, and was fully up in about 3 weeks time. The KBG just started coming up last week. Perhaps it wored so well because the PR was only 10 months old. Or b/c it got heat stressed. Or b/c I mowed it to ~1.8 inches before hand on the last mowing before starting the project. I also thinned the lawn fairly drastically prior to over seeding, by utilizing heavy core aeration (three passes) and also verticutting (two passes). I brought up a lot of dead and living grass in the process. I'm currently touching up the few spots that need it with a little extra seed. Here are some photos of the project (same area plus or minus a foot or two) at the various stages for reference (I do consider it a successful outcome even if it was my first time doing it and I learned a lot!): The top photo is the before photo, taken on 8/17/12. The middle photo is about ten days after overseeding, on 8/29/12. You can see the existing PR and KBG, and the TTTF was in the midst of germination, but is hard to see in the pic. And the bottom photo is from 9/21/12, taken right after the first mowing and application of starter fertilizer (I decided to hold off on the fertilizer until after germination so as to slow the growth of the existing grass to prevent it from overtaking the new grass. I'm glad I did this). Here is what I used for overseeding: -TTTF (approx 75% Firecracker LS and 25% Bullseye) -KBG (approx 33% each of America, Bewitched, and Rugby II) -A low amount of the existing TTPR seed blend (see below) was mixed with the fescue and KBG seed; I only used this in those areas that were really bare after the verticutting/raking. In this way, I created a uniform lawn in the bare spots that blended with the old grass. (The existing lawn prior to overseeding was a blend of KBG and three cultivars of TTPR sourced from from Allied Seed: ASP6005, ASP6002, and ASP 6001.)

************************************************************ ^ Yup. Your going to get a lot of similar answers. There was an immediate red flag when you said November and zone 4. Big no no. I'm in zone 5 (Zone 6 this year) and I overseeded in late sept. early oct. and was worried on being too late. Again like said above, also without knowing what seed was used, but likely a mix - the perennial rye sprung up quick and some may have made it, but if any KBB managed to come up it would have been too young and probably killed off by frost/freeze. You can just hope that it DID get cold real fast and a lot of the seed DIDN'T sprout and just went dormant which means it will sprout now. ************************************************************ I just re-read my post and should have worded it differently. The first sentence of the second paragraph was about me, and they rest was meant towards his lawn. My lawn came out absolutely amazing after taking months and selecting certain cultivars. I'm very happy this spring. (I think I actually seeded more like mid sept.)

Putting seed down in late fall or winter is known as dormant seeding. From what I have read, it is a very good way to seed a lawn, and you save water since the spring rains do most of the work. When you dormant seed you put down the seed when there is no chance is will germinate, too early can be a problem as you run the risk of getting the seed to germinate too soon. Before the first snowfall is a good time as this will prevent seed from blowing away, being swept away by rains, and as the snow melts it will work the seed into the soil. It's a bit early to dormant seed now in most of the USA, I would wait till the day before the first snow.

Fall is the time period when grasses go through a minor growth phase and then start storing energy for winter. We'd need photos to determine how fried it is, and whether it's likely to come back. At some point, feeding it is a good idea, but there's no point in doing that when it's dormant (bluegrass) or deeply shocked (fescues/rye). It does kind of look like normal rainfall will resume in early October, but we'll see. For now, water is probably the most important thing to get down to prep the lawn for spring. Dormant or dead grasses aren't going to store energy and won't look good in spring...