Okay, first, I'll covert those links to HTML so we can see them easily. I worked down in order of the links.

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why not wait until end of aug early sept to seed? you would've had better success dealing with weeds and heat.

Well they say timing is everything in life, and unfortunately yours couldn't have been worse in starting a cool season lawn. Your seedlings are probably suffering from heat stress, drought stress, and fungal disease. With soil temps above 70 degrees their roots aren't really growing. Some of it might survive the summer, and that should do well in the fall, but in my opinion the best thing to do is spray the whole thing with Round Up in the middle of August and reseed your yard around Sept. 1 (or earlier if you decide to use all Kentucky bluegrass). In a way it's good because you got all the weed seeds to germinate now, and if you do spray it all with Round Up, you will have very little weed pressure your second time around. Another issue you have is your choice of grass seed. If you have full sun, then it would probably be better to pick a blend of all the same type of grass (all rye, all kentucky, or all tall fescue). Under the rhododendron I would use mulch, it's not worth trying to maintain grass under bushes like that. If you want to mow it, go ahead and cut it around 2", but again, I don't expect most of the grass to make it till Sept.

Thank you for doing the essential homework in answering the questions before we asked!!!

Every spring I harp about how spring is the worst time to start a new lawn because the impending summer heat will kill off the tender roots of the new grass. The only worse time is summer. In all these years, though, nobody has actually admitted to seeding cool season grass during the summer. Your lawn is really the poster child of the problems with this.

Wait until the summer evening heat breaks to redo your lawn. Of course that is different everywhere but look for it towards the end of August or early Sept. The Bobcat was not a problem unless the soil was saturated. A real landscaper would know better than to run machines on wet soil. Forget about the -icides until you get the grass going. Just make do with what you have for now and continue doing homework. If you want to do something good, look at the Organic Lawn Care FAQ in the Gardenweb Organic Gardening forum. It is the last one of the FAQs.

Here is the 1-2-3 of basic lawn care:

2. Water deeply and infrequently. Deeply means at least an hour in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. If your grass looks dry before the month/week is up, water longer next time. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds.

3. Mulch mow at the highest setting on your mower. Most grasses are the most dense when mowed tall. Bermuda, centipede, and bent grasses are the most dense when mowed at the lowest setting on your mower. Dense grass shades out weeds and uses less water when tall. Dense grass feeds the deep roots you're developing in 1 above.

4. Fertilize regularly. I fertilize 4 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above.
   

I'm not sure I agree with the idea that the lawn MUST be re-seeded, unless the OP has decided he wants a KBG lawn. The Perennial Rye that was in the original mixture will eventually predominate over the KBG, so he will end up with a mostly PRG lawn. Some people do go that route. Not sure what the recommendation is for upstate NY.

So if he wants to change to KBG, then kill and reseed in September.

If he wants to salvage the PRG, then take a couple pics of the damaged ( not dead) grass blades and post those, so we can see whether there's a disease visible or not.

"I'm not sure I agree with the idea that the lawn MUST be re-seeded, unless the OP has decided he wants a KBG lawn. The Perennial Rye that was in the original mixture will eventually predominate over the KBG, so he will end up with a mostly PRG lawn. Some people do go that route. Not sure what the recommendation is for upstate NY."

The perennial rye cultivars in that mix do not spread. Any bare areas now will be bare in the fall unless some of the KBG made it and starts to spread. I said anything that survives into the fall should do well, but how much grass is left at the end of August is anyone's guess. There is nothing wrong with a PR lawn, they look great, and are easy to overseed if need be. Upstate NY is KBG country, and if it gets too cold PR can die off due to cold kill, but I have read this isn't as much as an issue as once believed. I happen to think monospecies lawns are easier to start and take care of regardless of what type you pick. My whole point is this; 2500 square feet isn't a lot of area to seed again. Most of the work has been done. Instead of having a weed filled patchy lawn, kill everything and do it over. The grass will do much better, the weed pressure will be minimal, and the lawn will be very consistent and thick into the winter.

As I said, it's up to the OP to decide which way he wants to go, either with the same mixture, or straight KBG. If he overseeds with the same mixture, he'll end up with mostly a PRG lawn. If he overseeds with just KBG, then probably over time the PRG will fade out in hot sunny areas, and survive in areas where there's more shade or foot traffic.

The rationale behind seed mixtures is that the grass type best suited for different lawn areas is the one to survive. My lawn is a mixture of KBG, PRG, and Chewings Fescue, and that has worked fine for me.

As for the weeds, he could just as easily put down a broadleaf weed killer, as kill all the grass and start over. Neither way is going to help with p. annua or other seeds already in the soil.

I'd still like to know what's in those colored patches, though.

Thanks for all the responses!

I think I am going to begin to mulch/mow soon.

Additionally, per Dave's suggestion, I am going to take a few pics of the damaged grass to see if any of this grass is salvageable.

But as tiemco stated, its only 2500 sq ft and I can always start over 9/1.

Nothing against you Dave11, but you're not correct. Perennial Rye is a full sun grass. It is less shade tolerant than KBG in most cases. Even though that mix is about 70% PR, and 10% KBG by weight, that will give you a fairly equal ration of the two grasses. PR seeds are huge, KGB seeds are tiny, usually 1-2 million per pound, whereas PR has about 200K seeds per pound. If you do the math out you will see that the ratio is pretty equal. The fescue will dominate in the shadier areas with that mix. (The OP has a full sun lawn, except under that bush, so I don't really see the need for shade tolerance.) I suspect that even if all the KBG germinated, it was probably the first to die in the summer conditions as KBG seedlings are fairly weak. Most mixes you buy in the big box stores aren't very well thought out, and they use mediocre cultivars in most cases. A PR/KBG lawn can look great, but most people stop watering once the PR is tall and ready for mowing, which means the KBG will suffer as it has just started to grow. A better way to grow a KBG/PR lawn would be to seed KBG first, then wait a week or two, then seed the PR so their time of emergence is roughly equal.

I follow your reasoning, but there was a controlled study done in recent years of mixtures of KBG and PRG, which showed that in such mixtures, PRG will come to predominate over time, unless the mixture is less than 20% PRG. If greater than 15-20%, over time, the stand approaches 100% PRG. I will look for the article. I believe the rationale is that PRG secretes a chemical into the soil which inhibits the growth of KBG.

My comment about PRG disappearing from a mainly KBG seeding is that the PRG won't survive a long dormancy as well as KBG, and so will disappear from the hot, dry, sunny areas. That's certainly what happened to my lawn, but I have no choice but to wait out the summer dormancy. If he keeps his lawn out of dormancy, that's different.

From the University of Idaho Extension:

"Perennial ryegrass germinates from seed considerably faster than Kentucky bluegrass and can overwhelm the other grasses in a mixture if there is too high of a percentage (over 20%). Perennial ryegrass will not fill into bare or damaged areas as quickly due to its bunch-type growth habit. It also does not form thatch due to its lack of rhizomes. Perennial ryegrass is slightly more shade tolerant than Kentucky bluegrass, but may thin out in shaded areas over time due to its lack of storage organs."

I think we're quibbling over nothing though. I think we both agree we'd like to see the OP establish a mainly KBG lawn, with little (or no) fescue or PRG

I am aware of the studies that you are talking about. Basically PR is so quick to germinate and establish that it essentially outcompetes the much slower germinating and establishing bluegrass. Also most people cut back on the watering once the PR is a few inches in height, which doesn't help the KBG. My suggestion of establishing the KBG first will alleviate that problem to a significant extent. Again, some of the blame lies with the seed companies that come up with these mixes. The effect of mature PR inhibiting KBG (or other grass seed) germination is called allelopathy. This is well documented, but it generally occurs with mature stands of PR, not seedlings, or very young grass. Again, PR does very well in full sun, as long as it's adequately watered. Many golf courses use PR for fairways and tees, so sun and heat isn't the problem, it's lack of water. In any case you shouldn't let a lawn go dormant in its first year anyway. I think we have gotten away from the OP on this one. My opinion is still the same, kill it all and start over in late summer with one species of grass, or if using a mix, one that is more intelligently thought out.

Hello,

I just wanted to follow up. I am going to begin the complete "do over" with the lawn and was hoping for some advice.

First, should I use the brand RoundUp to kill grass/weeds on the lawn? I dont want to open a can of worms, but ive read some unflattering things about the chemical. I dont mind using chemicals as long as they are safe for myself, pets and water (no well, but a storm drain).

If I RoundUp the lawn, or use any lawn killing chemical, how long should i wait before i put down seed? RoundUp recommends 3 days... that seems very short to me. Once the chemical finishes, I was planning on raking up the old dead weeds and the tilling the lawn to loosen the soil and get rid of the remaining weeds.

Finally, what seed should i use (FYI im in Zone 5, Albany NY)? I spoke with a person at a local garden center who highly recommended Jonathan Green Black Beauty or Jonathan Green Black Beauty Ultra which both contain Variety Turf Type Tall Fescue. Additionally, the ultra version contains:

10% Blue-Tastic Kentucky Bluegrass
10% Frontier Perennial Ryegrass

If anyone has any additional recommendations, please let me know!!

Thanks

Tiemco,

I know you recommended one species of grass, what brand and type would you think fits best? KB?

Regards

Roundup is the brand name for glysophate. There are other brands that will probably cost less. It's pretty fast acting and breaks down rapidly. The reason they say you can plant after three days is that it takes contact with the leaves for it to be effective. It won't do anything to the seeds. I've read of people who seeded the same day without problem, although I think it's safest to wait for the time the manufacturer recommends.

Since you're killing the lawn, it's probably worth the time, money and effort to buy sod quality elite Kentucky Bluegrass unless you have dense shade. If you've got spots with dense shade, you can use fine fescues for those areas. I'm not very good at picking good KBG cultivars, so I'll leave that to others. One good fine fescue mix I've read about is called Bonny Dunes. If you go that route, you'll want the KBG in the sunny areas and transition to the Bonney Dunes in the shady areas.