If you seed now, you'll probably lose a fair amount of the new grass over the summer.

When I think of reseeding, I think of completely replacing the lawn. When I think of seeding into an existing lawn, I think of that as overseeding.

If I were you, I'd leave the seeding until fall. Concentrate on fighting the weeds this spring and summer. Next fall (maybe late summer), as Soon as the heat breaks, mow the lawn as short as you can and rake the clippings (usually, I don't, but when I overseed, I want to expose as much soil as I can). Mowing short has a couple of things going for it. It helps the seeds get good soil contact, it helps the new seedlings get the light they need when they come up and it gives you more time before you need to mow again. If you mow too soon after the seeds germinate, the mower can suck them right out of the ground.

Then, if you can get a slit seeder, use that. If not, either power rake, dethatch or core aerate before putting down the seed. The reason for this is to get more soil exposed to encourage contact with the seeds. It's best then to lightly roll the lawn to help the seeds get contact with the soil. You can also spread some sort of mulch lightly over the seeds. For the next few weeks after seeding, you'll want to water the lawn lightly several times a day. You're not trying to give a good soaking, just to keep the seeds damp. Once the seeds come up, gradually cut back on the frequency and increase the length of time you water until you're back to the once a week watering.

If you decide to try seeding this spring, the steps are the same, but depending on how hot your summer is and how much water you can give the new grass, you may end up needing to seed again in the fall.

bpgreen pretty much covered it. When you have the luxury of waiting until fall, you should do it. The only reason to reseed in the spring is if you have bare dirt or you only have fescue with bare spots in it.

thanks, I will definitely wait until fall to reseed. Is a slit seeder something that can be rented at a local A1? What exactly does it do?
Cathy

You can rent them. One model of slit seeder looks like this...
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It has a series of rotating blades but they rotate on a horizontal axis. If you know what a rolling pizza cutter looks like, picture 50 of those on one axle. The motor rotates those and you adjust the height until it just nicks the soil through the grass. This will slice through any stolons or tillers on top of the soil and create a small micro furrow where the seed falls. It does minimal damage to the soil. If you have thatch, it will shred it and bring it up to the surface. The resulting surface looks like this...
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and the resulting seedlings look like this...
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