Yes, but the best approach is to apply fertilizer well before you actually sprinkle the seeds. Apply fertilizer with an NPK ratio somewhere around 10-10-20, or 10-10-10, depending on soil test results and the type of grass you're planting, about six to eight weeks before planting grass seed. This mix added to loosened soil will give the grass seed its best chance of getting off to a solid start. 

The best time of year for power seeding depends on your local climate. The soil should be warm, but the air should be cool. If the weather gets too hot after you grow new grass seed, it can die off easily. The best time for power seeding warm-season grasses is late spring to summer, and the best time for power seeding cool-season grasses is in the fall.

Yes, in most cases, grass will return after your dog urinates on it. But without preventative measures, there’s always a chance your dog will pee on the grass again, leading to brown patches come summer. This aside, even if your grass is dead in patches, simply reseeding the dead spots should help restore your lawn. 

If you choose not to reseed your lawn, unaffected grass surrounding the dead patches will spread over any dead spots. But be prepared for this option to take longer—you likely won’t be able to grow grass fast.

Yes, it's common for lawns to look bare after dethatching. Dethatching brings soil to the surface to create a "bald" look on your lawn. While you may choose to patch or reseed your lawn if bare patches seem excessive, it's normal for a lawn to look bare after dethatching. With the layer of debris that was blocking water, nutrients, and air from reaching your grass now gone, your lawn is likely to grow better than ever.