The temperature seems to be persistently below 20 degrees for the next few days/week. I’m going to mow briefly, dethatch, scarify, cover, and irrigate. I would appreciate feedback on two questions.
I have two Scotts fertilisers: 24-25-4 for starters and 32-0-10 for autumn. Which one is the appropriate one to use? Would I apply a starter when I oversaw and then, in the middle to late October, just apply a fall fertiliser?
Secondly, when is the appropriate time to apply fertiliser if I intend to cover with peat moss to safeguard seeds and retain moisture? Should the seed be placed before or after the peat moss?
If you did a soil test and need phosphorus, use the starter fertilizer. In most cases, that’s the best choice. However, wait until the seeds have sprouted and the seedlings are growing before applying any fertilizer. If you fertilize too soon, the existing grass will grow too quickly, and the seeds don’t need fertilizer just to start growing.
Oh wow. I’ve always read to put starter down when you seed, but you’re absolutely right, what will that do if they still need to germinate. Thanks so much 
Yeah normally people say that for simplicity.
I’ve got the exact products for this fall just sitting in my garage. Here’s my plan: I’ll seed this weekend, put down the Scotts Starter Fertilizer 10-14 days after, and then use the Fall Lawn Food about 6-8 weeks later, so around mid-November. My only worry is that it might be too cold in Southern PA to apply the Fall Lawn Food in November.
You can probably skip dethatching and definitely skip scarifying—aeration is better anyway. After aeration, topdress with Humichar if you can find it, or compost. This helps get organic material deeper into the soil, not just fill in the holes.
Then you’ll seed and cover. For fertilizer, you’ve got a few choices. When seeding, if you want to block weeds, you could use Mesotrione if you can get it. Otherwise, Scotts Turf Builder for Seeding has it mixed in—if you can find it, of course!
If you can’t get either of those, seed first, wait 5-7 days, then fertilize with the 24-25-4. I try to avoid walking on young grass once it starts growing, so I usually fertilize a day or two before the seeds start to show up.
You could use the 32-0-10 as a late-season feeding if the grass is still growing, but it might cause too much late growth. Alternatively, you can apply it when daily temps average in the 40s. The grass might be dormant, but the ground won’t be frozen yet, so the Nitrogen and Potassium will get absorbed by the roots and help the grass come back strong in the spring.
You could mix the two fertilizers at 50% each to get about a 27-12-7 blend, which is great for fall. It gives you good nitrogen for growth, plus phosphorus and potassium for root development. Apply the fertilizer before putting down the peat moss.