When it is finished decomposing, it is called compost and it is great for your lawn. Spread it on top of established turf or new sod at a rate of 1 cubic yard per 1,000 square feet. If you use more you risk smothering your grass. After you fling the stuff out onto the grass, use a leaf blower, a push broom, or the back of a rake to lift the grass blades out of the compost and allow it to sift down below the grass blades. All grasses will smother under a surprisingly small amount of compost.

The best time to apply on established turf was last fall. The next best time to apply was yesterday. Third best time is today. Since you don't have established turf, wait until you have mowed the new grass for at least two times before applying.

Since you have a rototiller, you are probably planning to till the soil before seeding. Please don't. The problem is that when you rototill, it is impossible to till evenly to the exact same depth for longer than 3 inches of travel. What you end up with is extremely fluffy soil that has to settle again...someday. It takes 3 years to settle and during that time it is settling down to the contour of the surface that you left underneath when you tilled. Since you have to leave an uneven surface underneath, the soil will settle unevenly. The result three years down the road is a bumpy lawn.

Assuming your current soil is already settled, simply preparing the surface is the best approach. If you have water pooling up near buildings or not draining to the street, then you need more help than you can do yourself. Hire a landscaper who will evaluate the situation, decide whether you need more or less soil, and use a tractor and box blade to make all that happen. The moment he leaves is when you seed the lawn and roll that seed down with a water fillable roller. The weight of the roller will "compact" the soil. The roller is the right weight when your footprints do not show.

Thank you for all of that great information! It sounds like we should seed the lawn first and then put the compost on at a later date, instead of just seeding into the compost itself. Do I have that right? We have clay soil. Last fall, we did a "test patch" and seeded into clay, and put shavings over the top to help retain the moisture. I was surprised at how well the grass came in. But I was leery of doing that over an entire lawn, knowing how compacted clay soil can get.

Thanks again for the feedback - we are learning so much from this forum!

Yes you have it right (by my book). And by the way, my book is the one you are reading here. Everything I think I know I have learned reading forums around the Internet. I came into forums many years ago thinking I knew about lawns but I have learned over the years that I didn't know squat. The people out doing it every day and having success after success are the ones to watch. My lawn's okay but I'm just a messenger.

The roots will loosen it some and the watering will loosen it some. What really loosens it is the many species of fungus that live in the soil. Just applying water on a semiweekly or weekly basis will provide moisture for the fungi to grow. Compost helps to moderate the moisture level in the soil so the fungi can really thrive. Aerating allows the moisture from subsequent watering to penetrate the root zone from all directions. I believe that helps the fungi to grow, too. I have a method that will make your soil so soft you feel like you'll roll an ankle, but it takes months to really do it right. Aeration, compost, and watering is a shortcut.

Most people say to apply compost and aerate in the fall. Six months ago I would have argued against both of those recommendations but I've done more reading. I agree with it. If you can wait until fall, that would be good.

If you are seeding now, watch for the summer heat. It can be killer on spring-sown lawns. In the summer let the grass grow as long as practical for the best heat protection. Use water carefully to cool the grass/soil but be careful not to water so much that you sprout weed seeds. Infrequent deep watering once the grass is established is best.

Wow, you have helped us a tremendous amount. I hate to think of the mistakes we would have made/money we would have spent had it not been for your advice and reading other posts.

I think we'll try seeding this spring and then apply compost and aerate in the fall. Letting the grass grow a little longer in summer sounds very sensible.

Thank you so much! We really appreciate your help!!!