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.)

Lutzd79, If it were my own lawn, I wouldn't worry too much at this point. If I recall, you're a bit farther north than me. My own Midnight II backyard only really woke up in the last 10 days. Give it more time. It looks like you have the beginnings of some growth. You have a new lawn, time should improve it. Just be patient. As for powdery mildew, I get some of that every fall in one part of my yard that is more shaded in late autumn. I haven't done a thing to rectify the problem It just goes away when conditions improve. I, of course, could be wrong. But powdery mildew on these grasses seem to be more cosmetic than anything else. Just make sure you do the proper cultural practices (cut high, water deeply and infrequently and fertilize properly) and you will probably be ok. These KBGs seem to be much more disease resistant than the old Turf-type Tall fescue and Rye mix that I used to have in my yard.

Three week old grasses are still usually single threads of the initial sprout, so you won't see much in your lawn. That having been said, surrounding grasses can and will choke out new grasses if they were already thick enough to have used the entire ground area for roots and/or the entire canopy for sunlight. Certainly the blank spots should fill in with KBG, however, and it can happily spread from there. Elites are famous for being more aggressive than older KBG cultivars. Cut at whatever height you like. While newer grasses will technically do best about 2", even much higher cuts will eventually work out. You'd actually have to have kept the old grass at 2" or shorter to open the canopy enough for overseeding to sprout--and that's only if there was ground space to do so. It's too late for that now, and it's not really what I consider important anyway.

dense turf...ya gotta love it. andy, i did an overseed not a rennovation...i don't think i could go through the rennovation process without pulling my hair out. so rather than do what you did, my plan was to aggressively aerate and overseed with better quality KBG/TTPR every fall for three years. I'm hoping that this course of action will eventually transition 90% or more of my lawn to newer/better turf cultivars...this was year two...i'm doing the same in my backyard, except it's shady so I'm working with various fescues. anybody have thoughts on the best course of action to rid my lawn of bent grass(about 10%, in patches that are spread througout the lawn) I can't stand the way it looks or the way it lays down flat. I'm thinking that next spring I'll just start digging it out and replacing those areas with KBG sod(which might take many hours of work)...OR.. I've also thought about growing a few dozen little 3"x3" pieces of KBG sod in planters under a grow light in my basement next March and then once it's established, planting 3 or 4 of these little pieces right in the middle of each of these bent patches(this also would require some work but i'm thinking it might be kinda fun to grow some pure little patches of elite KBG this winter) anybody care to strategize w/ me on this one?