Nicole Alderman wrote:Hi Nick, and welcome to Permies!
I'm not really an expert on growing a lawn. In fact, I'm generally trying to kill my grass so that I can convert it into edible stuff. Can't eat grass, ya know? But, you're looking for info on growing grass, not getting rid of it, so I'll see what I can do to help, and hopefully someone else who's grown a lawn from seed can chime in.
First off, this is a really great article on how to maintain a lawn: https://richsoil.com/lawn-care.jsp. Letting the grass get a little taller really does help it have deeper roots, and thus be healthier and need less water, as it can reach down and get it's own.
I'm wondering if rototilling your lawn area is actually necessary--grass seeds seem to love sprouting up everywhere for me, without any rototilling. Do you want a lawn that is 100% grass, or would you be okay with some tasty dandelion and other useful "weeds" growing in there, as long as it all looks green?
If you don't care about some weeds, you could probably just:
(1) Lay down the hummus and manure without rototilling (you probably didn't even have to rake out the leaves, as they'll just compost into nutrients if left there),
(2) Add the correct amount of lime (make sure to read the bag so as not to over apply the lime! Without a soil test, you can overdose the lime and raise the PH too high),
(3) Spread the grass seeds and keep them watered.
Once the grass starts growing, you should only need to water when you stick your finger into the soil and it feels dry about 1-2 inches down. Then water deeply. It's better to water deeply infrequently, rather than to just water a little all the time. When you water deeply, it encourages the grass to grow deeper roots, which means you won't have to water as often--less work is always a plus, in my opinion!
I hope that helps!