Hi Flowergrower, welcome to the Far North Forum.

I had to google 'fat grass' as I had not heard of it (I thought it was some sort of ornamental grass - which I have a bit of an obsession with, LOL).

Anyway, looks to me like a pretty good forumula for lawn topdressing. Using peat and vermiculite would ensure you're not bringing any weed seeds into your lawn likek you might by getting a load of topsoil, plus those ingredients would help with holding some moisture. I'm sure the 8-12-6 fertilizer would be fine. The excessive watering must be for getting the grass seed to germinate.

My only suggestion would be not to bag your clippings, at least for the first few mowings or you might just suck up all your hard work. Mulching mowers are better for lawns anyway.

Here is a link that might be useful: fat grass

Hmmm.

That's not a recipe I'd use on grass in our 'Prairie' city...maybe it's fine for somewhere out East. Here in our ecology, a natural grassland with low humidity, no way I'd use peat and similar dehydrators that wick away moisture. If you want thick grass then skip the formula and sprinkle well rotted sheep manure over your lawn, use lots of water and and 'voila'. Easier, cheaper and better results (in our ecology).