So what are the steps to overseeding tall fescue? I have never done this before.
Step 1 - wait until fall. If you skip that step, don't bother with the rest.
Step 2 - cut the lawn low and rake up the debris. You should be able to see soil between grass blades.
Step 3 - spread seed and fertilizer
Optional step 4- spread spread straw, cellulose or other seed starting material
Step 5- water 2-3 times per day until the seed germinates. Slowly back off to once per week.
billl's step one is the most important one for best results. The time to do it is when the summer heat breaks in your area. Depending on where you live that could be as early as early August or as late as Halloween. Tend toward getting it done early to allow the grass time to fill in and develop roots before winter hits.
The problem with skipping step 1 and seeding now is that you will germinate every crabgrass seed in the turf when you get to step 5. So whether you spend the money on seed now or not, you will have a crabgrass lawn by July. I suggest you take proper care until August and then go for the seed.
1. Water deeply and infrequently. Do not water every day unless you want to sprout weed seeds. Deeply means a full inch or more all at once. Infrequently means no more than once a week in the heat of summer. Less often now.
2. Mulch mow at the mower's highest setting. Tall grass grows nice deep roots to take advantage of the deep moisture you are applying in 1 above.
3. Fertilize regularly. For synthetic fertilizers like Scott's, that probably means Memorial Day, Labor Day, and Thanksgiving. Easy to remember dates.
Agree with both of the above, i did this last Fall. Fall is better so the grass doesnt compete with the weeds. Kills weeds til fall. Then do as bill suggested. Come end of fall it will thicken up nicely.