If it was me I would give the fescue a chance and see how it does. Some areas may be better than others so a bit of hand weeding and overseeding may be enough to keep it afloat.
If it looks hopeless, just spray it down with vinegar, and overseed then. I don't think there is a wait to seed after using vinegar.

I agree that for now, you should give it every chance & see how it goes. Now that you've done all the reading you have, you know about the proper cultural practices of watering infrequently & mowing at your mower's highest setting. I would add that if it gets to the point that you choose to "just spray it down & reseed" to wait until fall. Do it right after the heat of summer is over, giving you the best chance at getting a good stand of turf for next summer's heat.

My 2 cents,

Dan

Maplebirch & okcdan - thank you for your replies. I'll see how the fescue does. I'll weed everyday if I have to in order to avoid the chemicals.

Tilling was a mistake but not for the reason you think. The biggest problem with tilling a lawn is that when the dust settles, it settles unevenly. You will have a rolling, lumpy, bumpy lawn. Mowing high will help hide that, but it won't be good for sports or playing on.

Have you read the FAQ on organic lawns over on the Organic Gardening forum? You can start fertilizing any day now.

dchall - thank you for your reply. Our lawn actually seems to be flatter than it was before I tilled it. I didn't go down very deep and I was careful to rake it out before I seeded. My main purpose in tilling was to break up the top layer of the soil and also to pull up the weeds. The soil was so hard I didn't think the seeds would have a chance if I just sowed them on top of the ground. The small amount of grass we had in our lawn before was very clumpy fescue and it was very uneven.

I have read the FAQ. I do have a question about fertilizing. I was going to wait and use corn gluten meal when the forsythias bloomed. Should I use soybean meal or something else now and then use the corn gluten meal later?

Thanks for your help.

Our lawn actually seems to be flatter than it was before I tilled it.

I'll give you three years to reconsider that statement. Soil settles for a long time.

You can fertilize now if you want. Generally a spring feed is not completely needed unless you want a bigger burst of growth than the normal spring flush. It will give you much darker greens. Keep in mind the CGM is also a great fertilizer. Depending on the cost, I might use CGM now at 15-20 pounds per 1,000 square feet and then again in 8 weeks. Those would both be considered reasonably heavy so expect lots of dark green grass.

skyblue - I tilled 2 years ago to since I needed to regrade and had similar soil conditions to what you described. It's still flatter than it was and doing great. While I wouldn't consider it perfectly flat, it's still great for playing with the kids, dog, playing croquet, bocce, etc. Maybe over the next few years that could change, but so far so good and I have a much better yard than what I started with.

I also made the "mistake" of tilling...all things considered, it wasn't much of a mistake. Three years out, the lawn is flat and I have only one minor problem (caused by deep-buried construction debris that I couldn't remove without an archaeological expedition and lighted helmets).

I did have a water infiltration problem until the soil settled and re-established proper pores, but that only took a few months.

Plan to deal with the inevitable minor problems that arise on any lawn and don't worry too much.

I like DCHall's feeding plan quite a lot. I already fed once (far north of you, so the weather hasn't turned yet) organically, and will do so every month until it starts to get too cold (October, here). With the organics, timing seems to matter a lot less.

Thanks dchall, thejonstewart and morpheuspa for your comments. Our lawn looks so much better now than it did at this time last year. I mowed it this week with the mower set at 3.5 inches and I am still pulling weeds. I'm going to put corn gluten meal on it this weekend.