If they're in the state I think they are, they're fine. Marginal, but it won't be an extreme problem and you won't notice any issues by the time the sod is installed (which, in 7a, is a while yet for any grass type; April is about the earliest date).

I might have recommended dropping just a bit of high-nitrogen fertilizer atop the leaves to assist with decay, but that's also going to require oxygen, so the time to do that would have been in November, not now. Burying that would end up being worse that simply burying the leaves by themselves.

Whether you actually have clay is always an argument we enjoy around here (you probably don't but it depends on your locale (even most locales "famous" for clay soils don't have them in all areas; most soils act like clay if the ion balance is wrong or if the soil deflocculates, but it's a long story and can be fixed).

And whether adding that much soil is appropriate is also another question. Just be careful not to damage your grading and move water flow into inappropriate locales like your garage or basement... :-)

Thanks. Maybe I should add 1"-2" topsoil only? I'll have to remulch 2" anyway to replace the decomposed mulch if i don't install sods. Otherwise the entire yard turns into mud pit in the rain, plus erosion problem.

It's Northern Virginia. The soil looks orange, very compact, full of rocks and roots. It was a wooded area too. But now with the neighbors having all their trees removed, half of our yard now has direct sunlight and the other 1/3 has afternoon sun. I am using tall fescue sods. Do i still need to add fertilizer and lime before putting the sods on? I thought mid Feb is a good time for sods (seeds, or any spring planting)?

Sod should be added when the grass can actively root, so for you (not too far from me in terms of dates of spring, actually), that would really be early April at the earliest. February sodding would risk freezing out, dry rooting, and death. Sod's also going to need to be kept damp, so doing this in February is...well, a challenge. April, not so much. April may be a bit cruel, but the weather is usually just fine for grasses. Cold for us is actually A-OK for grass root growth.

Really, you can sod in late March through May, and late August through October. You can do so in summer, it's just much harder.

Don't fertilize when you sod, it won't want it. If you do, use Milorganite or another very gentle organic to do so (it's generally what they use at the sod farms). It'll feed slowly and gently, and the new sod doesn't have the root systems to absorb much in the way of fast nitrogen before it washes out anyway. There are ways to manage that but...it's easier to simply use Milorganite, which slow-releases via biological methods.

Lime isn't a good idea unless you have a soil test stating that it's required, what kind of lime to use (both dolomitic and calcitic exist, although I never recommend dolomitic due to the fact that it's very slow to work, always contains too much magnesium in comparison to calcium, and is so poorly ground it's always impossible to spread properly).

That the soil itself isn't even does present a problem. While blindly changing your grading is a bad idea, you also can't install sod on uneven ground. I might be tempted to use just enough soil to even the ground out, and install sod on that. Good to perfect sod-soil contact is required. As long as you're sure you're not pitching things so that the water won't end up in the cellar... If there's any doubt, definitely get an expert in to consult on the grading before doing that. A couple dollars spent there is well worth it rather than having the cellar pumped.

If you have a low spot that is 1" to 2" deep, then bring in new soil. If your soil is graded and draining fine, then do not bring in more soil. As it is you'll have to fix the old soil. If you bring in "good" new soil, you'll still have to fix that. So just leave it alone...unless you have some holes to fill and bring up to grade.

We are house hunting and recently saw a house with an unusual lawn condition. Near the house the soil was low, and out toward the street the soil was high. The grass in the low spot was recently resodded, undoubtedly due to disease from the area holding water. Next season it will all die again unless the new owners have the entire yard graded. The area by the street was high enough that the landscaper might have to haul dirt away to fix the drainage before leveling it.

Regarding clay soil: somewhere in the archives of this forum is a post from someone complaining about his "red Georgia clay." After a soil test, it turned out to be red Georgia sand. The redness comes from iron in the soil, not from they clayness.

Hi, after adding topsoil, can I just rake it then put the grass sods directly on top? Or do I still need to tilt the topsoil to mix with my existing half-composed leaf and clay soil? Which soil is better for new sods, topsoil with orgrow compost mix, or topsoil with leaf compost mix? I'm ordering them now for late March delivery.

Okay you either did not get my message or you have already had your yard evaluated by a professional, but in any case I'm going to assume the worst and shout the gist of my previous message. DO NOT ORDER MORE SOIL, unless you have a professional landscaper tell you that your soil is too low. Bringing in new soil does not fix the problem. The new soil could be worse soil than what you have. You would be trading one soil for another - that's not fixing anything. Your old soil can be fixed. In fact, based on what you've already done, your current soil is almost guaranteed to be much, MUCH better than any topsoil you can buy. Mulching is always the best thing you can do. Mother Nature does it every fall. But without an evaluation by a professional, you have a 50-50 chance that a professional will want to haul some of your current soil away, because you already have too much. We don't know that. If you could post a picture of the yard from out in the street and one near some concrete curbing, driveway, walkway, or something, then we might get a better idea of what your situation is.

Here is an example of a yard where they have too much topsoil. It gets this way from adding 1/4-inch every year.

You cannot see the 3-d effect here, but you can see that the sidewalk taking off to the right is hidden by the grass in the hell strip. I'd guess there is 6 inches too much soil in the middle of that strip. Out toward the edge and the street it has washed away. You can sort of see the slope up to the left of the sidewalk in the foreground. In the background you can see where the topsoil from the yard has washed out over the sidewalk. It is so thick with soil that the lawn is growing in the middle of the sidewalk. One of the reasons they have trouble maintaining this yard is too much topsoil. This eyesore is a bed and breakfast across the street from this little town's historical district. I met the owner once and offered him some free advice. "I'll get back to you," was his reply.

Regarding clay soil: Here's another picture

You should be able to see clearly that there is a difference between the soil in the foreground and in the background. I know what the difference is because my nephew drove the truck that made the difference. The homeowners along this road complained about too much dust from the traffic on the road. The solution is to spray magnesium chloride to "hold the dust down." This is the same mag chloride used in the north to salt roads covered in snow. What the mag chloride does is allow the sprayed soil to absorb and hold moisture for a long time. The picture was taken in the late morning. The moisture retained in the background soil is from the morning dew the night before. And it is not dusty when a car drives on it. Okay so that illustrates the difference between water retaining soil and the other stuff. Excessive buildup of magnesium in the soil will cause the soil to retain water much like clay does in the soil. It also causes the soil particles to tighten up much the way clay is a tightly bonded type of soil. In the end, a soil with too much magnesium will look and act like a clay soil. Even a sandy soil with too much will have the worst of the clay like properties. So before you assume you have a clay soil, it is a good idea to have it tested professionally to determine what the issue is. You have already performed the steps to fixing a soil with real clay (repeated heavily mulching). However, if the problem is too much magnesium, then you will still have that problem unless you address that.

DO NOT TILL THE SOIL. Whether your landscaping consultant orders you more soil or not, do not till it. Do not let him till it. Your soil could not be more perfect than it is right now with all the mulching you've done. I wish everyone would take the time to do that. All you have to do to it is to put the right surface on it. Make sure your yard drains away from the house and has no dams which hold water up close to the house. If your soil has high spots, away from the house, those will hold water up close to the house, and you don't want that. Again, the professional will help you make those decisions. But assuming you have small, localized high spots, scrape those off and drag that soil to the localized lower spots to make it all more level. If you still have low spots after scraping all the high spots, then bring in only enough soil/sand to level everything out. And do not rototill that new soil into the old. There are reasons for this, but I've already exceeded the attention span of almost everyone who might be reading this, so I'll let that rest for now.

"Excessive buildup of magnesium in the soil will cause the soil to retain water much like clay does in the soil. It also causes the soil particles to tighten up much the way clay is a tightly bonded type of soil. In the end, a soil with too much magnesium will look and act like a clay soil."

Which will lead to a necessary soil test that nobody will read here any longer and lead to a lot of chemical games in the soil that nobody wants to play and years of corrections just to try to get some sort of fix into place.

"Just don't go there" would be the basic takeaway point. :-)

My yard is currently covered in snow so I'll take the pictures after the snow is gone.

Can you explain why I shouldn't tilt the soil? I think my soil quality is good now, but last fall leaves are still only partly composed (it usually takes 2 years for it to completely turn into dirt.) That's why I am thinking of adding 1-2" topsoil on top for the grass roots. Or you say I can just lay the sods directly on top of my half-composed leave mulch layer? All the lawn service people want to haul my leaves away and tilt the soil underneath.

None of my neighbors has any problem growing grass directly from their existing soil. I couldn't before due to heavy shade and surfaced tree roots. Now I have more sun (neighbors removed all her trees) and I had all surfaced tree roots dugged up. There are still tree roots deep down and the yard suffered from erosion, but years of mulch does add back the soil it lost.

Tilling of soils (as I'm sure dchall will reiterate) results in bumpy, uneven surfaces that lose their drainage and puddle water until they restore themselves. The bumpiness never restores itself properly and one is generally stuck with that forever.

Tilling is fine in a garden where evenness doesn't matter (but that destruction of proper drainage and soil structure still happens).

However, the tiller will dig much deeper in some areas, not as deep in others, and result in uneven soil and denser or not as dense areas that are higher and lower and bumpy. That'll result in the mower bouncing when you mow, an uneven mow, and a very, very unpleasant experience mowing.

Trust me. It's just not worth it.

For your leaves, rake them to break them up before installing sod, or rake to remove as much as possible and expose the soil surface. Tedious, yep. But that's the proper method.

Burying those results in them decomposing underground, which is yet another problem. That will steal oxygen from the soil, and that's another bad thing in that grass roots only go where there's oxygen. Until the leaves finish decomposition, grass roots won't easily penetrate that layer. One-inch roots aren't sufficient for survival.

"Rake them to break them" means to rake the leaves up so they'll break down faster? It still take a while, doesn't it? I cannot install sods in the summer heat and in Sept there will be more leaves falling down. I didn't want to remove my precious last year leaf mulch but looks like I have no choice.

Thanks for your explanation about the tilting.

I wish I had a good graphic to show the results of rototilling. As morph said, you'll end up with high and low spots even after you took every precaution to make the surface level. The problem is underground. A hand held rototiller will dig in deep where the soil is sandy or moist and will bounce up and out of the ground if it hits a root, rock, pipe, or hard/dry place. You just cannot get a perfectly level surface underground. Then when you level it out on top, you have varying depths of fluffy soil on top of the harder soil. When it settles, over the course of 3 years, it settles most where the deeper spots of fluffy soil were.

The best thing to do is to fix the surface of the soil if it needs it. Do that by scraping off the high spots and filling in the low spots. The lay the sod.

If you have a mulching mower you might consider chopping up the leaves. In any case don't forget the first rule of laying sod. "Green side up" hahaha

This is what the leaves look like btw. I'll post the entire yard photo when the snow melts.

The thin areas can be run over once and left. That thick stuff in the corners should be picked up and composted, or picked up and redistributed atop the new grass once established (that's also always an option). :-)

More photos

Hi again. I just finished putting the sods down. How long (how many minutes) do I water each time? I spent an hour watering in small sections the entire 1,800 sq ft of sods but the soil layer underneath was still not wet. It looked as moist as when I first got the sods delivered in opposing to drying out, but not wet. The sods had come Saturday with healthy dark green color and now some of them turned yellow.

Also, I tried but the a few parts of the ground wasn't perfectly flat, so should I use a lawn roller to press the air bubbles (if any) out, or watering it will eventually bind the roots down to the soil properly?