Growing grass in clay soil

cdw1982April 23, 2012

I have unsuccessfully been attempting to grow grass in my backyard for years. There are a few areas that are covered in some vegetation mostly weeds but the majority is just hard compacted clay. I have tried using one of those slicer machines that puts slits into the yard and seeds but nothing has stuck in those hard dirt/clay areas. I was considering tilling the area and mixing some topsoil into the whole yard. The time to seed is now, so I don't know what to do before attempting. Should I till the hard clay, I can barely stick a shovel in it, I don't see how anything will grow there without tilling it.

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Tilling will just stir up more weeds. Just add plenty of GOOD topsoil and then put grass in.....if you're in the South, Bermuda sod is the way to go so long as it gets plenty of sunlight.....

    Bookmark   April 23, 2012 at 5:09PM
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Lots of good topsoil. I am in the north, built on clay soil. Where I didn't put topsoil never grew much of anything, so I finally spread the soil and it grows well.

    Bookmark   April 23, 2012 at 7:23PM
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dchall_san_antonio(8 San Antonio)

The time to seed is NOT now. The time to seed is in the fall. This is a horrible time to seed and it's getting much worse very quickly. You can do it now but please don't buy expensive seed. Save your lawn budget for seeding in the fall. Then get the good seed.

Where do you live?

Good topsoil can be created out of the soil you have. Also, look up "jar test" and do that test on your soil. Take pictures at 2 minutes, 2 hours, and 2 days. That test will prove to you that you do not really have clay. What you likely have is an excess of magnesium in your soil that hardens it up like clay. Do the jar test so you can get over the "clay" excuse and never bring it up again.


The best way to recover hard soil is to cover it with a couple inches of mulch. Not everyone is ready, willing, and able to do that, but it really works. 2 inches of mulch for 2 weeks and the soil will be noticeably better. Leave it longer for better soil.

Another possibility is spraying the soil with baby shampoo. The shampoo is a surfactant that allows the water to penetrate deeper into the soil. Ultimately this has the effect of softening the soil through biological mechanisms. The rate is 3 ounces per 1,000 square feet. Use a hose end sprayer. Measure your area and pour the required amount of shampoo into the sprayer. Fill the rest with water, stir gently so you don't foam it up, and spray evenly until it is empty. After you do this water the soil for about an hour (or however long it takes to get 1 inch of water). A week later, water the 1 inch again without the soap. A week after that, repeat the soap and irrigation again. That should do it for the rest of the season.

Note that these are not instant fixes. Both approaches delay the time you would want to put seed down. If you are anywhere near the south, the good news is that bermuda seed does not go down until June anyway. If you are farther north, you are out of luck for this season. Any seed you put down now will be crabgrass by July. I know, pretty pessimistic, but that's what we see here year after year.

Really need to know where you live for best advice.

    Bookmark   April 23, 2012 at 7:48PM
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dchall, the 2 inches of mulch, what can be used for the mulch?

    Bookmark   April 23, 2012 at 11:34PM
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dchall_san_antonio(8 San Antonio)

In Texas we have a pest plant which is a juniper tree but we call it cedar. It is a pest because it spreads and robs moisture from other nearby plants. But when shredded it makes an excellent mulch. I would suggest using a mulch made from a local pest tree if you have something like that available. Otherwise not a bark mulch. Bark mulches float away. When a mulch is made from an entire plant, like our cedar, it seems to stay put better. So you might find a local tree trimmer who uses a chipper/shredder to chip tree limbs and use their stuff. Sometimes you can get that dumped on your driveway for free.

Do a search on ramial chipped wood.

    Bookmark   April 24, 2012 at 8:09AM
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How does anyone know what to tell this fellow?
We have no idea where he lives or what sort of thing he wants to plant....

For all we know - he lives in Australia and wants to plant that weird Crabgrass stuff they call "Blue Couch"

I agree that the plan for just covering the soil in compost or mulch for a couple of years is a useful one regardless... but it may not fall within our OP's desired timeline....

Key questions...
1. Where do you live?
2. What specific type of grass are you trying to grow?
3. Have you recently had a proper "Soil test" done by a lab to determine mineral deficiencies?
4. Other pertinent information you haven't told us... like how much shade, water, pets, etc...
5. How do you know your soil is "Clay" - have you ever done a Soil Structure Test (mayonnaise jar test) or had it professionally analyzed? 99.9999% of people complaining about "Hard soil" don't have Clay - they have Sandy something or another...

If so - please post a picture of your mayonnaise jar "Soil Structure" test along with the other stuff...


    Bookmark   April 25, 2012 at 1:32PM
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Sorry that i didn't provide more information initially.

I live in Saint Louis, MO, I'm growing grass in a shaded area (doesn't receive much sunlight at all), I haven't had any soil test done, the ground is hard and compacted and difficult to dig into with a shovel I don't know if it is clay necessarily. There is some vegetation in my backyard but it is all weeds, with little spots of actual grass.

I'm just really sick of staring at dirt and having an ugly backyard, and am totally clueless to what to do.

When I attempted to seed with the slitter last year some grass initially came up but nothing stayed. I just want to know what to do so this doesn't happen again. I don't know how to post pictures to this forum, any help would be appreciated. I just want to have a solid plan to getting my yard in a decent condition.

    Bookmark   April 27, 2012 at 8:36PM
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"I'm growing grass in a shaded area (doesn't receive much sunlight at all)"

This could be a big reason why you are having trouble growing grass. Grass needs sun. Some need more than others. In heavily shaded areas you will have trouble growing most of the major warm and cool season grasses. How many hours of sun does the yard receive on a typical cloudless day? What kind of grass seed have you been trying to grow for years?

    Bookmark   April 27, 2012 at 9:00PM
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I second the shade issue. I would do the compost layer anyway no matter what you do. I'd listen to tiemco and answer those questions. They are crucial. In my current house I grow a great stand of TTTF in shaded areas, but that's because I get 6 hours of sun closer to summer. My prior house, the bck couldn't grow any grass but it got 2 hours of dappled sun, maybe. It's a huge difference to turf grass.

    Bookmark   April 28, 2012 at 2:56PM
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I also live in Missouri and am planting a new yard soon in an area with a high clay content. I have read that rye seed will grow well in clay soil and am thinking of planting rye over the winter to help improve the soil and planting fescue in the spring. What is your opinion of this. Any help is greatly appreciated. I will be planting this in a very sunny area.

    Bookmark   September 4, 2012 at 7:51PM
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dchall_san_antonio(8 San Antonio)

Gotta warn you that I'm just a little frustrated here. HofmyH, did you read all the replies above? Did you read the one from John_in_SC about almost nobody has clay soil? It's always best, especially when you are tagging onto a defunct thread, to read the contents of the thread before posting. You need to be sure the previous suggestions either don't apply or you have followed them.

Please do a jar test (search this forum or the Internet). The jar test will demonstrate that you do not have much clay or it will make me look foolish. I don't mind looking foolish, and I'd rather do that and get it out of the way than operate out of misinformation. The problem is there are some salts in your soil which can make it look, feel, and act just like clay, when in fact it is 90% sand.

On to your question. DO NOT PLANT RYE NOW AND FESCUE IN THE SPRING. Okay that should take out the last of my frustrations. NOW is the time to plant fescue. Today. Planting now will give the fescue plants all winter to harden off and develop a root system that can withstand next summer's heat. If you plant rye now, it will not die off until May at which time it is far too late to plant fescue. You would have 100% crabgrass by the first of August.

Since you are planting in a sunny area, you might want to mix some Kentucky bluegrass, or go 100% with KBG. It is your choice, but I thought I'd put that out there.

If you think your soil is clay, you probably think that because it is so hard. The reason it is hard is you have lost the population of beneficial fungi that cause soil (even clay) to soften. The fastest way to get that softness back also happens to be the cheapest and easiest. All you have to do is spray with any clear shampoo at a rate of at least 3 ounces per 1,000 square feet. Do that and then irrigate with 1 full inch of water. Repeat in 2 weeks and you should be good for a full year. What that does is allows water to penetrate deep into the soil and hold the moisture content fairly steady. The beneficial fungi love those conditions and will regrow very quickly. Picture a loaf of molding bread. If you leave it under ideal conditions for even one day, the entire loaf is engulfed in green fuzz. That same thing happens in your soil.

    Bookmark   September 4, 2012 at 8:11PM
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There is a product called Aerify Plus that is supposed to recondition clay soil after time and regular applications. From what I have seen this stuff looks pretty legit.

    Bookmark   March 4, 2013 at 11:23PM
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There are a couple of issues that lead to the compaction you're describing. The clay content is certainly one aspect, but the shade brings up the other. Soil particles in clay do form tighter bonds, which can be offset with the introduction of bio-products that have been used to improve soils for centuries (cow manure, produce compost, etc). The second issue is actually two-fold; the trees that are providing the shade, also tend to canopy the rainfall and draw water from the soil surface. This creates meniscus pull on the soil particles, which tightens them to a point where the hydraulic conductivity will no longer support a root system as substantial as that of turf grass.

I won't join the debate on when to seed, it is really based on current soil temperatures and forecasted temperatures while the turf establishes, but I will say that cultivating the soil and adding 1 yard of compost per 500 sqft will improve your results dramatically. I also recommend a soil test from your local extension agent, to determine if lime or gypsum are needed. Clay soils that are low in Calcium tend to really tighten up and get compacted.

I also linked a job I did in similar circumstances last Fall. I wish that I had photographed one in which I used a tiller, as it might be more applicable in your case, but this will give you the idea.

Here is a link that might be useful: helpful photos and tips

    Bookmark   March 5, 2013 at 10:13PM
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