Punching holes is a good idea, but I would be surprised if it restored things to normal. The more holes the better.

Have you ever heard of a reason for laying plastic sheeting under a lawn?

Also, should I go with a spike aerator simply to slice the lawn/plastic up?

Landscape sheeting was often used to stop weed growth, but it's usually installed either just under the soil surface or just under mulch in beds. These days, we use tight mesh instead as water and air can theoretically penetrate while weeds can't (in practice, things don't work out so well).

This is one of those cases where a deep aeration makes sense (it's rare, but happens). I'd aerate heavily--extremely heavily, even to the point of breaking up the soil surface--in the interest of shredding as much of the plastic as possible. If there's such a thing as a slice aerator that can go down the full six inches, so much the better.

That's going to damage the grass heavily and probably encourage plenty of weed growth. Again, this is one case where that's better than allowing the current state to continue.

Where the plastic was unbroken for decades, the biological state of the soil will be...well, it won't really have a biological state that resembles top soil in any way, shape, or form. That presents plenty of problems, but fortunately the anaerobic conditions down there won't last long. The fact that the soil is now toxic from the anaerobic activity...well, it'll wash out. Eventually.

Post-aeration, feed heavily and organically to kick some biology back into gear. Plan on continuing to do so for the foreseeable future, so a year at least.

Bacteria and fungi will restore reasonable populations this summer and fall with good care. The organics will help restore the lawn, but you'll be plagued by weeds until the system is back in balance. Worm populations...I can't say. Several years, certainly, until those restore themselves, and if too much of the plastic is still in place, I wouldn't count on that.

Thanks morpheuspa. I actually meant spike aerator. Should I just till/cultivate the lawn and pick out the plastic and start from scratch?

I wouldn't. In this case, not because it's going to destroy the soil biology because that already has huge problems. But more here because it'll render your soil permanently uneven and you'll never get back to a nice smooth surface with minimal bumps.

I'd aerate repeatedly, including repeating it in fall (perhaps just before a reseeding). And simply accept the weeds it's going to cause from doing it so heavily.

Till then use roller?

You're never going to roll the bumps out. Tillers dig deep in softer soils, but skip over rocks, roots, and clods of harder soil. You end up with a low spot where the soil was softer, high where it was harder. And that hard soil won't roll down.

Stig, he's telling you not to till. It really is important not to till where you want to have a nice lawn. Rototilling leads to a bumpy surface that can scalp easily. Rebuilding the soil structure after tilling takes 3 years, so it's not something you can roll out.

I really like the idea of a spike aerator rather than a core aerator.

Thanks guys. Aeration it is. Fun as it would be to race my tractor over a tilled and pot holed lawn and the spinal repercussions of that.

Hey, if racing the tractor around is your bliss, I say go for it. :-)

Actually, if your tractor has a box blade attachment, the game here might change considerably. In that case, you CAN even out your soil very well even post tilling, and let it settle, get rained on, and then level it again. That will give you nearly a perfect soil.

In case you are serious about racing your lawn mower

http://www.letsmow.com/

So Rototill, then pick out plastic, then box blade, then hydroseed?

Thank you morpheuspa, and others. Very much appreciate the help. Now I just have to bring myself to do this. I am sure that staring at the lawn will motivate me. Especially when the next large patch gets so toxic even mushrooms die.

Hi- so what happened with your lawn? What did you do and result? I just bought a house and have the exact same problem. Found previous owner of 36 years placed sheet of plastic about 3 inches under entire lawn to stop grass from growing. Yikes! What do you suggest from your experience?

I work for someone with a very nice newer home, and black plastic under the entire back yard lawn. Just 2in deep. The lawn floats above it when raining. It's gotta go huh.?

It's gotta go. Alas. The plastic disallows the roots growth any deeper than 2", destroys the biology under the plastic, and was a complete mistake in the first place.

If the lawn floats, it might be as easy as cutting apart the lawn, removing it as sod, and taking out the plastic a piece at a time. Replace the sodding, and move on. It'll be heavy as heck, but it can be done if you move small sections at a time.

Re-establish it by watering deeply once or twice. Two inch deep sod isn't really sod, it's full-on grass. You can do that any months except for October through March in most areas (you didn't mention where you were).

If that's too much to handle, get a sod cutter, cut it as sod, and move it that way. Re-establish as "sod," which means keeping it damp for a full month. Just damp, not wet, sodden, soaked, squishy, dry, dusty--damp like a wrung-out sponge, then back off slowly.

thank u sir. I'm in Redding CA. let ya know what I do.

The map's a bit different in most of California, and for you in Redding, which is deep in Logland. Given the weather, you may very well have a southern grass (your weather never really freezes, and it's what I'd call desert hot in summer), so if you know you don't have fescue, rye, or bluegrass, let us know. Those would really best be done in spring to give them time to repair as they'll flourish over summer.

In your summer weather, which is what I'd call "intolerable with no rain," northern lawns (fescue, bluegrass, and rye) would best be done now through February when they're at their best and you actually see occasional rainfall and decent temperatures. They'll at least have your "rainy" March (heh, all of 10 days of rain!) to grow back in before searing out for summer. :-)

I suspect you have a southern grass, so let's also see if DCHall chimes in here with some advice. He's lived in California. I haven't. I'm simply playing the average weather against southern grass averages. :-)

I live in Maine and have same problem. I bought a house only to find the previous owner placed a sheet of clear plastic on the entire front yard and just let the pine needles fall on it year after year for 35 years. After I got the pine needles raked/ removed (huge job), I saw pieces of plastic - I was dumbfounded! Who would do that! The septic field is on the front lawn and needs to be replaced because it is 40 years old. I need to have 6 huge pine trees cut down before we dig up old septic and replace it. Septic company/ soil test expert/ tree removal company said they will remove the plastic when septic work is done and till/aerorate through the other areas of lawn which will chew up and remove that plastic before they place new soil and seed, etc. Any recommendations? I have trees all around the back lawn and live near a protected environmental reserve. No plastic in back of house - thank goodness.

If they're going to take care of it, no problems. I'd recommend against tilling simply because you'll end up with a bumpy soil surface (not important in a garden; very important in a lawn where you'll be mowing it and bouncing on the mower wheels).

ETA: Aeration, however, is fine! They can double or even triple-aerate that area and it won't be an issue at all. It's not really necessary--nature will do the work for you over time--but it will accelerate the process and certainly won't hurt. /ETA

As to why...it's often placed as a weed barrier. It works, after a fashion, as long as there's no soil atop it, or not enough to grow much root and not enough rainfall to keep the soil damp enough to sustain weeds.

For the soil choice, make sure they get something close to your local top soil...but they're pretty certain to do that. Because that's going to be cheapest anyway. :-)

For the seed...they're probably going to use an inexpensive tri-mix, which is most likely to match your lawn if you don't already know what you have. If you have a specialty lawn, make sure to speak with them (my HOA dropped tri-mix lawn due to an inability to flex, listen, or act like anything other than obdurate...but I don't use that language). You have the advantage of working with people you hired, so that shouldn't be a problem.

Thank you! appreciate information to ensure I covered all bases. I wondered about lawn in Spring because read better to do lawn in August. I am in Maine so not sure about best time for new lawn. I am eager to get project so I can get rid of plastic and have a lawn some day!

Maine lawns are...odd. It's always best to do the lawn in August, but in most areas of Maine, you can often get away with a spring installation since summers are...not exactly summer in the rest of the nation (I've been in Portland in July and that is not what I'd call a summer. Of course, I was out in the Calendar Islands many times over several months for many years, so it does tend to be cooler there as well).

If you have to do it in spring, it's more doable there than most other places--just make sure to water it well through the first summer, particularly if it's hotter than average. Dry spells aren't tolerable to younger lawns, so they'll have to be coddled through. And you'll probably have to reseed in August anyway, but it's not going to be like you'd have to reseed in, say, Philadelphia.

Your feeding schedule is going to be September 1st and October 1st on that lawn and shutdown is likely to be in October. There's no real winterizer feed for lawns up thataway but that's OK, the tourists are gone by then. :-)

Well here I am researching and my lawn has the similar issues. There is a thicker white plastic under the turf of my lawn. I noticed it when I pulled up a plant and during power racking. I live in Washington State and was not nearly prepared for our hottest summer on record. Usually lawns are pretty easy due to the rain and moderate heat. This summer my lawn ended up looking like a fire happened on top of it after 109 temps. My neighborhood lawns held up well, but mine is a horrible eye sore. I put down weed killer and moss killer in areas then power racked the lawn and laid down seed. It's day 8 some grass has grown but its not doing so evenly, have a small four leaf clover patch and there are black spots in the lawn. But I do not know what to do. Any advice ?

@Meosha, did you remove the layer of white plastic? If not, you probably wasted your efforts :-( And depending where in WA state you reside, it is pretty late in the year to expect grass seed to germinate well (even if no plastic present). It has just gotten too cool this fall faster than normal and current low temps do not encourage successful seed germination.

This sounds like a spring project - reseeding or overseeding in spring (mid April to mid May) in the PNW is perfectly acceptable and a common practice as conditions remain cool and damp long enough into summer for the lawn to establish properly before we hit that midsummer dry and hot (for us!) spell.

But you will never develop a good healthy lawn with the plastic remaining in place. That must be removed!