How long will seed last in ground?

I had some seed slit seeded about 2 weeks back all over my yard. Since I’m limited on what I can water, I’ve really only prioritized and focused on my front yard, which has had pretty good results so far. My back yard, which I have barely watered, obviously hasn’t had anything. So I’m curious, how long will the seed last in the ground? I’m about to do my first mow in the front (cut low in the back again) so I’m considering dialing back the watering, although I’m hoping to get some more germination/spread, so not sure. Would it still be worth watering the back yard at this point, or just continue focus on the front? Looks like I will have a late first frost this year (45039, Ohio).