I know there's like 30 questions here but they should be easy for some of you. This really should be copy & pasted and someone(s) makes notes along the way. Please only reply if you are well experienced/knowledgeable in lawn renovation/overseeding. Thank you so much.
If a lawn is like 60% weeds and has dead spots and you want thick grass, should you: A) slit seeder in opposite directions making a "#" pattern, B) Don't use any machinery such as a dethatcher or poweseeder but instead just throw down seed and then topdress with 1/4" soil and possibly also put down a little soil before the seeds to help soil contact C) detach especially if there's over 1/2" thatch and then overseed so the seed touches the newly exposed soil created by the dethatcher and possibly put a 1/4" soil over the seeds also.
Or a combonation of the above? And since it's %60 weeds, the process will have to be repeated for years as it slowly gets better instead of completely ripping out and redoing the whole lawn in one shot?
If a lawn is in really bad shape like %85 weeds or all dead brown or all moss, besides completely sod cutting the whole lawn out and then putting new soil and seed or sodding, is the only way to get thick grass by doing the above method(s) year after year untill it finally becomes a thick lawn? You might say yes, but I saw a professional video that I can't find now where, with good results in only a couple weeks, a homeowner recorded them covering the entire dead lawn with like 3" soil and seeds and then rolling after mowing on the lowest setting so the top of the existing lawn was well below the new soil. But I have to ask because I've seen many people spend a lot more effort and money ripping out entire lawns and then adding soil and seed instead of just smoothering the existing dead lawn.
If the lawn is in pretty good shape, what's the best method to make it a bit better or at least maintain it's current state? E.g aerate and then spread seed and/or run a slit seeder and/or dethatcher even though it's a decent lawn already has a healthy 1/4" of thatch and those machines can stress the lawn and pratically rip it all up? How about topdressing the whole lawn with soil and seed instead? If the lawn's already perfect, should anything be done to preserve the condition like aerating besides the obvious making sure it's mowed, watered, and fertilized correctly?
If a lawn is so bad that completely covering it with a few inches of soil and seed is needed instead of just slit seeding or dethatching without adding more soil, (not sure if this is possible for such a bad lawn and asked above already), would it be okay to first put down a 3" layer of chipped lumber (pine etc trees) over the entire existing weedy lawn and then putting a few inches of soil and seed over the wood chips? I ask because a 1/2 acre lot I'm clearing has many bushes and trees up to about 10" diamater and the lawn is basically %100 weeds but after clearing all the trees, I'm growing grass everywhere and might be able to save money and work by having the trees chipped and scattered on site and then planting grass over the chips. I know unfinished compost shouldn't be added when trying to grow new plants because the decomposing compost takes away some of the nitrogen (or something like that), but it might be possible.
When I patch a spot, I put about 15 seeds per square inch as per instruction. When overseeding an existing lawn that is in decent shape, should I put as much seeds?
I don't plan on using a lawn roller unless I can successfully do the method of putting like 3" of soil over a really terrible lawn after mowing it on lowest setting and then seeding it instead of ripping out the entire lawn and hauling it away. I know at least something is needed to shake the seeds off the existing grass so they fall to the soil, like dragging a chain link fence or a 2x10 lumber, but the lawn will be watered right after overseeding anyway which will drop the seeds down.
If I don't know exactly what strains of cool season grass a New Jersey lawn already has and am fixing spots or overseeding the whole lawn, what's a good mix to get e.g %33 fescues %33 bluegrass and %33 rye?
I know Fall is better for overseeding that Spring, but how are you supposed to overseed with leaves falling and raking/blowing them and leaves also blocking sun light? I usually just mulch mow over leaves which will probably smoother and kill seedlings. Or would overseeding have been doen too late if the leaves fall and the seedlings aren't at least 2"ish? If the seedlings are 2"ish and then the leaves fall, will mulch mowing the leaves really damage the seedlings? What's the best window of time for Fall overseeding in New Jersey region? Mid-late September AKA whenever gives the seeds about 3 weeks to be 2.5" once the leaves really start falling? I don't know exactly when the leaves will fall or the first frost date, so a window of time would be good to know.
I know if trying to grow under a pine/evergreen tree to use shade-friendly grasses such as rye and fine, tall, and red fescues and to prune away all branches under 10' and trim the canopy to allow more sunlight, and as long as 4 hours of sunlight hit per day and pine/evergreen needles are removed routinely and extra watering, it should be okay if the pH is tested and the correct amount of lime is added if needed at the time of seeding. But I'm wondering if it's possible to put like 3" soil and lime on top of the layer of pine needles already on the ground without having to removing them. I doubt it, but just asking. If I do have to remove the needles, then should I definitely add fresh soil or can it sort of be okay if I just slitseed new grass and lime into the soil that the needles were laying on? I know lime can take years to alter the pH and might need to add more each year, but wondering if leaving the needles under a 3" layer of soil is possible.