My first thought is to seed in the fall after the summer heat breaks and the evening temps start to come off their highs. That gives your new grass all winter and spring to develop strong roots for the summer heat. But you missed that.

I'm afraid you are doomed to another year of crabgrass, at least to some extent. Kentucky bluegrass is self healing, but dogs can be pretty tough on turf, especially newly planted turf. KBG takes a little longer to establish than fescues but fescue will not heal after it is dug up - at least not in the time you want it to heal. Please don't worry about crabgrass because next fall you can do the things needed to get rid of it altogether.

You said you kept your soil moist. Moist is too wet. Once the grass is established, the surface of the soil should be allowed to dry out between watering. While you are seeding you need to water several times a day for a few minutes. Most people water 3-4 times a day for 10 to 15 minutes. After the grass comes in, you can back off to once monthly during the cool seasons and then once weekly (depending on your soil and humidity) during the summer heat. Infrequent watering allows the soil surface to dry out and PREVENTS crabgrass seed from sprouting. It needs nearly constant moisture for a few days to germinate.

The other thing you can do to improve your cool season turf density is to mow at your mower's highest setting. That allows the roots to grow deep and also shades the soil surface from the sun. Crabgrass also needs full sun to sprout and take root.

Thus if you have at least some Kentucky bluegrass in your turf, you are mowing high, and watering infrequently, you can stop crabgrass from invading your lawn.

The last thing is fertilizer. In the north I would fertilize with organic fertilizer on Memorial Day, 4th of July, Labor Day, and Thanksgiving. If I was using a chemical fertilizer like Scott's, I would use the same schedule except SKIP the 4th of July application because salty chemicals in the heat put too much stress on the grass plants.

You can aerate if you want. A lot of people feel the need to do that but I don't. I think it is a way lawn care professionals can make their boat payments in the fall and winter.

I agree with Dchall with a couple of exceptions. Roots do not grow in the winter in Zone 6. And, if you are using crabgrass control, you are not doomed to crabgrass this year in Zone 6. You have from when the grass begins to green until the Forsythia is done blooming to get the crabgrass control down. Your decision is one of three choices: (1) control crabgrass but wait 90 days to seed (which in Zone 6 means into the beginning of summer - the worst time to seed), (2) seed and live with the crabgrass this year, and (3) there is a more expensive crabgrass control than allows seeding ($$$).
If you decide to go with option (1), you can wait until August 15th in Zone 6, and get back into the "optimal" seeding season for Zone 6.

I have been trying to thicken up a back yard lawn for a couple of years now. I've always done the 'rake the yard in the spring and overseed' method with little success.

Raking in the spring is great. But over-seeding is best done in the fall.

I'm planning on aerating this Spring. From what I've read, I would have been better off doing it in the fall, but I missed that chance.

Aerating would be best in the fall followed by overseeding.

To make things more difficult, I have three large dogs that can easily tear up the lawn when they run and play. Last year, I fenced off the portion of the lawn that I overseeded for a couple of months. However, I'd say about 75% of the grass that grew ended up dying even though I kept the soil moist and used a starter fertilizer. I've never aerated the lawn for the 7 years I've been in the house. I suspect the roots stay shallow due to compact soil.

Spring overseeding is not recommended because the new seedlings easily die out in the heat of summer

One more wrench into the mix....crab grass! I used Scotts starter fertilizer with crab grass control. I'm convinced this does not work! Thoughts?

Siduron used in Scotts starter fertilizer is the least effective crabgrass control.
So my questions are:

1. What is the best grass seed to use in Northern climates that is not only traffice-tough but self-repairing?

Kentucky Bluegrass. Available as a monoculture and commonly found in mixtures with fescue and rye. Scotts premium sun and shade mixture is an example.

2. How early should I aerate and overseed so that I can also put down crabgrass control after the seed germinates?

Aerate in the early fall. DonÂt worry about weeds until the next year. Apply crabgrass control (dimension) the following spring.

3. Any other thoughts?

Yes  Concentrate on strengthening your existing lawn this year. Crabgrass preventer in spring when forsythia in bloom.
Mow long, water deeply but infrequently, fertilize, control broadleaf weeds by spot treatment with weed-be-gone. Plan on aerating and over-seeding in the fall if you think it necessary at that time.

Thanks in advance!
You are welcome.

Here is a link that might be useful: Steps to Overseeding

I also like Kentucky Bluegrass. Get yourself an aggressive cultivar that will repair itself quickly (ie. Emblem, North Star, Limousine, etc.). I would do it in the fall though. For spring, get the crabgrass under control--I have heard Halts works fine. Just make sure you water it in and repeat it if needed...I think it only last 8 weeks or so.

If you remember Bestlawn, a former member here, she has written a great set of recommendations for Kentucky bluegrass cultivars, state by state, click here.

Crabgrass control and trying to grow grass seedlings at the same time is not a real great combo.

In addition to the good suggestions above, I would suggest a couple of things. First, do you get enough sunlight on the yard to allow any cool season grass to thicken up? If it doesn't get full sunlight, do a search here on the forum about sunlight and grass to see how much is needed and what you can do if you are in between (more shade tolerant varieties).

The second thing is, as you suggest, overseed in the fall so you can get the grass established before tackling the crab grass control issue in the spring. It dies in the winter, so, overseeding then has a better chance of establishing. Second, as mentioned, you can then apply pre-emergent to best effect in the spring. A good coverage of new grass seedlings and the pre-m should work together to hold down the crabgrass.

Lastly, keeping the dogs off the new seedlings for several months should also help them a good bit in getting established. I've fenced my back yard for just that reason to good effect a couple of years ago. I basically made a dog run on the side for a few months.

Good luck.

Thank you for all of your follow-ups. It sounds like overseeding this Spring does not make much sense.

Would it make sense to at least aerate prior to putting down the crab grass control?

Fall is usually considered a much better time to over-seed. If you can push a screwdriver 6 inches into the ground without hammering it, then you probably don't need to aerate. That being said, it probably wouldn't hurt to aerate if you think your soil is compacted. Do aerate prior to over-seeding.

I top dressed my lawn using the directions on vcompost.com and some vermicompost that I had made prior. This worked better than any fertilizing that I have ever tried. I also found that I needed to water the lawn less, cause the soil held the moisture better. Amazing Results and not as difficult as you might think, definately helped to level the lawn out as well.

Here is a link that might be useful: top dressing guide

The most improvement I have ever seen in my yard(s) came after applying a topdressing of 1 yard per thousand sq ft of compost.

Quite a bit of work, but, nothing really beats it. Especially for yards that haven't had it done in a while if ever.

If you have the time, money and backmuscles, I highly recommend it.

Some smart handyman needs to work out a way to inject compost from a hopper into a leaf blower to blow the compost onto the lawn.

I know the insulation blower companies can use their equipment to blow compost onto your lawn because they do it down here. I'm talking about a leaf blower for smaller jobs.

Yeah, I'm with you David, there is just no good equipment for the weekend warrior to put out compost. There is some fairly large and expensive equipment that might work on a commercial scale. but is not economical for the once every year, or less crowd. And, apparently, there isn't enough rental demand for it for rental shops to handle it.

But, anyone who has ever done it by hand (wheelbarrow, shovel, broom, rake) would pay a pretty nice price to be able to rent POWER equipment to ease the job.

Funny you should mention this because I was alos thinking of spreading some peat moss as well. I've seen peat rollers but I've done it before with a shovel and rake. Obviously, peat is easier than compost.

We're lucky enough to have a pretty huge pile of compost at our transfer station (dump). I'm still considering doing my own pile.