I'm a fan of aeration, but I've read the holes are too deep for the seed.

Dethatch with the dethatching blades set to just barely nick the soil. Mow the lawn short, and bag it this one time.

Then seed over the top of that. Bluegrasses are slow to establish, so your existing lawn is likely to need mowing before the new grass is ready to be mowed. Be gentle and try not to slide.

By overseed, do you mean just spreading seed? Or were you going to rent another machine for that?

My original plan was to rent a power rake, aerator, and an overseeder machine from Home Depot, over the course of a few days. But I only have 1 day available this weekend to overseed, so I doubt I'll have enough time to go back and forth to Home Depot 3 times in one day. I could probably have enough time to rent 2 machines. So I'm not sure what my priorities should be. (My lawn has never been dethatched or aerated either.)

Some websites say you can just spread seed on top, other websites say that is useless without some form of topdressing (which renting an overseeder would do).

Thank everyone for you responses

You only need one machine to do both. Just rent the slit seeder. It will have fixed blades. It can be used as a verticuter (de thatcher) and a seeder. Do not rent a machine with flail blades or spring tines as they are solely for de thatching. Many manufactures make a fixed bladed machine for de thatching and by adding a drop spreader to the front they produce what the call a slit seeder. (google Renothin (dethather/slit seeder http://ryanturf.com/products/ryan-power-rakes-dethatchers/ryan-ren-o-thin-power-rake/ and Billygoat overseeder http://www.billygoat.com/Product-Categories/List/overseeders-power-rakes) Just make sure it has FIXED blades.

For an established, but thin lawn, set the depth so that it just engages the soil. Run the machine over the lawn. Rake the debris. Spread the seed with a walk behind spreader at 1-2# per ksqft. That one run will do damage to your lawn (so be prepared), but de thatching and then using an over seeder will do really significant damage to the existing turf. Add aeration and you'll need a divorce lawyer.

Do not use the spreader that comes with the overseeder/slit seeder ,if that is what you end up renting. They have a history of inaccuracy and of spilling/leaking seed.

Great advice. So, you recommend making one pass with the overseeder to dethatch/engage the soil, then broadcast seed? No second pass after I spread seed?

>>> No second pass after I spread seed?

>>> It's kind of thin, but no bare spots.

Based on your description, yes. Each pass you do will do damage to the existing grass. I suggest only one pass (with no more than a 1/8-1/4" cut at most into the soil to get some benefit of the slit seeder) to reduce damage to what is evidently an acceptable existing turf. (If you only want to remove thatch and open bare soil for the seed, then just allow the blade to touch the soil.) However, if you determine that you and your current turf can handle a second pass, feel free, but it will cause quite a bit of damage.

If you do a second pass, you can consider lowering the blade so that it cuts 1/4" or so deep (as you've decided to bite the bullet) for the seed to fall into. If you rake after the first pass, you can broadcast seed before the second pass and take advantage of the benefit of the slit seeder by allowing the blade to bury the seed.

Unless all you want is to de thatch, make sure whatever machine you get has fixed, not flail or spring, blades.

And cut your existing lawn down to 1 1/2" before you start and bag it if you can. You can also bag again after running the slit seeder, it'll help reduce the raking.

I think this was already said but the power rake is a dethatcher. You said overseeder. Did you mean slit seeder? A slit seeder does the same thing as a power rake/dethatcher except the slit seeder also drops seeds. If you can only rent one machine, the slit seeder is the one you want.

As for aerating, you don't need to and it would be counterproductive when seeding (and always). Dropping seeds into deep holes is not how you seed grass. Grass seeds germinate right at the top surface of the soil. Anything buried even 1/4 inch is unlikely to germinate and take root.

I'm curious as to why your lawn is thin? Do you have shade? How do you water - how often and for how long? When were the last two times you fertilized and what did you use? Have you used any insecticide or fungicides in the past year? Have you used any organic fertilizer in the past few years?

So the general consensus is that as a last step, I can just broadcast seed, and it will grow without topdressing. That is a relief. I guess my plan is to:

--cut lawn short

--aerate (ground is compacted)

--dethatch with rented overseeder, set a 1/4"

--broadcast seed

Thanks guys

NOOOOOOooooooOOOOOOOoooooo! Don't aerate. In fact: 15 yard penalty for withholding information!! Did it just get compacted since you started this topic 4 hours ago???

True compaction is not what you have unless you've been parking the car on it during rainstorms. What you likely have is hard soil. But either way, core aeration will not help solve that anywhere close to what shampoo will do. You can go ahead with the seeding for now or you can do all this simultaneously. Spray the yard with shampoo at the rate of 3 ounces per 1,000 square feet. Follow that up with 1/2 to 1 inch of water to wash it down in. Shampoo is a surfactant that allows moisture to sink deeper into the soil. When that happens your soil will come alive with beneficial fungi which perform the function of softening your soil. The process takes about 3 weeks and can last forever. If after 3 weeks your soil is not noticeably softer, you can reapply the shampoo again. The more you use the softer it gets. First, though, test how hard the soil is by pushing a screwdriver into it. Hard soil is difficult to penetrate even 1/8 inch. If you can sink the entire screwdriver into the soil easily, you don't need the shampoo. Try the screwdriver test with the soil dry and again after you have watered it. If it is about the same before and after, then you need the shampoo. The soil should be hard before watering and soft after watering. When it is soft you will feel it just walking on it. Core aeration will never (never EVER) accomplish the same results you'll get from the shampoo. You might ask how 100,000 lawn care professionals could be wrong about aeration and I'm right. Well, they are. It will only cost you 50 cents to try it for yourself. Actually the most serious of lawn care professionals, the sports turf professionals, have been using surfactants for decades. Shampoo is just the poor man's option. It really works.

Okay I'm powering down now...whew!

Otherwise you're out of order with your plan. Dethatch first, then mow with the bag on to collect all the fluff and clippings. Then seed it. THEN, roll it down or walk over all of it to press the seed down onto the soil.

dchall,

I don't think a rented overseeder, Classen TS-20, will do the exact same thing as a power rake. I hear the TS-20 can convert to an power rake, but that home depot locks the blades into overseeder position. Or something like that. I think a power rake has blades closer together.

I just want to aerate to ease compaction. The lawn hasn't ever been aerated.

My lawn gets full sun. It's never watered besides rain. I usually fertilize once every spring. I did fertilize this spring with Scott's starter fertilizer + weed preventer. That did help a lot. But the lawn has had wild violets the past 7 years. I dug a lot out last year and have hit them numerous times with herbicides (still not all dead), so there are less and less each year.
I hear a thick lawn is the best weed preventer, so here I am trying to thicken up the lawn. I've already bought 10 lbs each of Jumpstart & Midnight KBG.

Withholding info? Hmm...I guess shampoo is worth a shot. How soon after shampoo can I seed?

>>How soon after shampoo can I seed?

Instantly. Or you can drop the shampoo atop the seed, it'll actually help with initial water penetration and it's a trick I use when starting flats of annuals.

I don't mean to sound cruel. but you may be wasting your time. You're going to need to fertilize more than once a year and you'll need more than rain to have a thick lawn. Even this seed is going to need light watering for 3-5 weeks to germinate and watering next Summer to even survive.

Shampoo will save me hours of time over aerating, so it won't hurt to try.

I'm not looking to have a perfect lawn, just relatively thick and weed free. My grass is always green in the spring and fall, it just goes dormant during the heat of summer. I hear its better to let it go dormant than half-ass watering. Isn't that one of the benefits of KBG, their ability to recover well from dormancy? In the future, I do plan on fertilizing in both spring and fall, I was even planning to aerate every fall.

I will be watering the new seed multiple times a day for a until the Midnight seeds are at a mowing height. That's interesting that you say I need to water it next summer in order for new grass to survive. If that needs to be done, then I'll do it, because I don't want to be wasting my time.

Like I said before, my lawn has never been dethatched or aerated. It has a lot of thatch so just getting rid of that will do wonders for my existing grass.

Its dormancy is one of the many reasons I selected KBG, but even KBG needs a minimum of (IMHO 1/2") water every three weeks to prevent some die off. KBG needs/loves nitrogen. Minimum schedule for KBG is 1# end of May, one pound early September and most importantly, 1# once the grass stops needing mowed-around mid November.

Just an FYI, since I did this myself last weekend. If you rent from HD the "Power Rake" and the "Overseeder" are EXACTLY the same machine except for the spreader at the front. After I took back the "Overseeder" I decided I should have a look under their "Power Rake" and it had the same exact blades underneath. Save yourself the money and simply rent the "Power Rake" and then use your own spreader (The 4 hour rate is about $20 less) . That is unless your HD rents different machines than mine.

A note: Classen models do come with different blade/rakes so it is possible to have the models rented by HD do different things. The problem is like any big business they save money by having them all fitted with the same "multipurpose" blades and not the "slicer" blades or the "rake" tines.