Question
I live in Rhode Island. Because of extreme dry summer this year, 3/4 of lawn died (or has not come back so far). I have a few questions:

1. Would it come back next spring if I do nothing?

2. Should I reseed now or wait till next spring?

3. How do I reseed an entire lawn? Should I overseed by using a de-thatcher? Or should I use a rototiller to start from scratch?

Someone told me that I could use an aerator first and later followed up with seeds and fertilizer? Is that correct?

For your information, some areas of my lawn has almost no thatch or roots left while others have more thatch.

Also, I am going to test my soil. Should I reseed after I know the soil test result?

Thanks so much for your help. I look forward to hearing from you.

Answer
Good evening Lisa:
The information I will attach should answer many of the questions that you have asked. I cannot tell you, without observing your lawn, whether or not it will return next spring. If you have a Kentucky blue grass lawn there is a better chance of it reviving. Kentucky blue grass spreads by tillers so if there are roots that are alive it can rejuvenate itself over time. If there are large bare spots that area is more susceptible for weed growth and disease. As far as the thatch is concerned it will not be a problem unless it is over ?inch thick. If it is it would be a good idea to de-thatch or aerate those areas.

Some information on Cool Season Grass Dethatching:
Kentucky Blue Grass should be de-thatched in the early fall and not during summer. A second choice is early spring after green up. The idea is to allow enough time for re-growth during the cool weather. Follow with slow release fertilizer at a rate of one pound per thousand square feet. Remember, each time you fertilize you must irrigate afterward. Tall fescue and perennial ryegrasses are slow to build up thatch. They are also slow to recuperate from dethatching, since they are bunch grasses, which produce no runners. If you must de-thatch these two grasses, do so in the early fall. You may follow with reseeding if the damage is severe.
Kentucky blue grass varieties differ in their ability to produce thatch. The taller, upright, light-to-medium density cultivars produce less thatch than the lower growing, denser varieties. Low thatch producing types would include South Dakota Common, Delta, and Park Kentucky blue grasses.
The more aggressive Kentucky blue grass types which would produce more thatch would include Mystic, Touchdown, Princeton 104, and Warrens A-34.
Heavy thatch producing Kentucky blue grass varieties are desirable from a wear tolerance standpoint.

Some information on soil testing:
Testing the soil is the best way to determine the nutrients your soil may be lacking and the amounts required to provide the best start for your lawn. A soil test will also indicated the soil pH (acidity or alkalinity) that may need to be adjusted. Soil testing information and services are available through private testing companies or your County Extension office. When you send your soil sample in to be tested, request that the testing service provide you with fertilizer and other amendment recommendations for your lawn.
To take a soil sample for testing use a spade, trowel or bulb planter to remove a plug of soil six inches deep. Obtain similar cores from other random locations in the area of your lawn. Do not take samples were fertilizer, manure or other chemicals may have been applied. Mix the soil thoroughly in a clean pail. Remove about a half pint of the well mixed soil and let it dry at room temperature. Remove debris such as leaves, vegetation, sticks and large stones. Fill the soil test container to the amount required. Either mail or deliver to the soil test facility.

Some information on Overseeding a lawn:
Timing is critical to assure success when seeding lawns. Mid August to early September is the ideal time for seeding cool season lawns in your area. Late March through April would be a second choice. Seeding in late spring through mid-summer often leads to problems.
Mow the area to 1.5 inches to reduce competition from established grasses.
If you did not have a soil test apply a starter fertilizer (high in phosphorus) over the entire lawn at  a rate of 1.5 lbs per 1000 square feet.

For successful overseeding, it is critical that seeds be placed into contact with the soil, whether seeding into live or dead turf. Seeds scattered on top of live or dead turf rarely produce a decent stand of turf. Several ways exist to place seed in contact with soil.
To open the soil for seeding in large areas, use gas-powered vertical mowers,
slicers, core aerifiers, spikers, or slit-seeders. All of these tools should be available at most rental agencies.

Core aerifiers open soil by inserting hollow tines into the ground and removing
plugs of soil. When using a core aerifier for overseeding, it is important that at least 20 plugs per square foot be extracted. After broadcast seeding, allow
the plugs to dry and use a drag (a piece of chain link fencing works well) to work seeds into the soil and crumble the plugs.

Another method you might consider is a slit-seeder. These are recommended when you presently do not have a thatch or compaction problem.
Slit-seeders (mechanical overseeders) are considered to be the most convenient
method of placing seeds in contact with soil. These machines combine a
vertical mower with a seed spreader. They open the soil with a vertical mower
mechanism, and then seeds are metered at a predetermined rate from a holding
hopper through feeder tubes and dropped into the slits made by the vertical mower. Machines often have a roller that firms the soil after seeding. Slit seed the area twice; the second pass should be at a 45?angle to the first pass.

To renovate successfully, adequate water must be available from seeding through germination. Water the newly-seeded area three to four times daily. Light, frequent irrigation is the rule. Try not to allow newly overseeded areas to dry once watering has commenced. Maintain a constantly moist seedbed. As newly germinated seedlings begin growth, decrease watering frequency and increase the duration to encourage rooting.

Mow frequently to limit the competition from the established turf. Mow at 1.5  to 2 inches until new seedlings have been cut at least two times. After that, raise the mowing height in 1/2 inch intervals over the next three weeks until a normal mowing height of 2.5 to 3.5 inches is reached.
In late November apply a winterizer fertilizer to create good root growth for next year.

A web site that may be of interest to you:
Copy and paste to your browser and hit "GO"
http://www.umext.maine.edu/onlinepubs/htmpubs/2367.htm

I hope I have helped. Have a good lawn!
Floyd McMahon