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My wife and I have been living in a new subdivision for the past two years and have been struggling with getting grass to fully take in our backyard. Our front yard is sod and has been doing fine, but the back is a heavy clay mix since the developers scraped off the top soil and sold it (so we've been told).

I have tried a fescue mix in the past, but it seems to die out rather quickly in Mid-July when the heat is at it's strongest.

Are there any specific seed mixes that work better in clay, or other techniques that can help us with our yard?

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  • What is your hardiness zone?
    – WienerDog
    Commented Mar 21, 2012 at 14:21
  • I am in WL Indiana, and it looks like a five or six arborday.org/treeinfo/… Commented Mar 21, 2012 at 14:39
  • This link has lots of good information about improving clay soils. finegardening.com/improving-clay-soils I think it's more aimed at gardening but hopefully you can apply some of the knowledge to your lawn.
    – Philip
    Commented Jul 10, 2014 at 20:01

7 Answers 7

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I've seen this many times in new subdivisions. The worst was a house with heavy clay soil where a year after the builder left you could still roll up the grass. As you have found grass finds it hard to get roots into a compacted clay subsoil.

I assume that you are not able to remove the existing grass and add two to six inches of topsoil. That would solve your problem immediately but would change the drainage around your house and that's never a good thing.

Stopping the grass from browning out in the summer when water loss due to heat is more than the roots can take up from the soil could be as simple as watering once a week during the dry periods.

A longer term solution is to sow more grass seed and top dress twice a year, spring and fall, with compost to a depth of 1/4" to 1/2".

Another solution that is hard to back out of is to plant clover and thyme. Clover will break up the clay and add nitrogen but cannot be easily removed once added to a lawn.

As far as grass mixtures for most homeowners the choices are "Shady lawn" or "All purpose". The only difference is the ratio of different grass species. For real success you need to improve the underlying soil.

Good mowing practices help too. Cut late in the spring and cut as high as you can stand to let the roots store energy. Continue cutting higher in the back yard during the summer and then cut lower in the fall to avoid snow mould if that happens in your zone.

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If you're lucky then gypsum will work on your clay, helping the clay break up. Put a bit of the clay in a glass of water for a few hours. If the water becomes milky, i.e. the clay disperses (without any human intervention such as shaking), then gypsum will work. Spread generous amounts of gypsum when the clay is moist or even additionally spike the clay using a fork (or even turn it over) and add the gypsum. The alternative is to add at least two inches of crusher dust (finely ground basalt) and rotovate it in. Organic matter doesn't help clay soil particularly. An unamended clay soil will never grow a good lawn as grass roots suffocate in the airless environment, drowning when the clay is wet and baking when it's dry. Clay is only ever at a good moisture level for a very short time between being an airless wet mud and dry and hard as a brick.

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Regarding growing grass in clay...I have never seen anything but the best lawns in clay! Living here in the Northeast, I have only experienced a great, thick, plush lawn from a clay type soil. A lot of the reasoning is clay holds the moisture which is one of the best,if you will, fertilizers ever. Just rototill or rough up the ground, throw a good seed with straw over it, light watering and let it grow. Good luck, Jim

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Normally a light tilling to break up the clay, apply some topsoil and grass seed on top, rake lightly so the seed is about 1/8 inch deep into the topsoil and cover 100% with hay and keep watering until you see new grass sprouting up. The key is loosening up the clay soil and keeping the hay on top damp to shield from the sun/heat, and to hold the moisture in until the seed can sprout.

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Clay tends to be alkaline or acidic. Here our natural pH is 5 and the topsoil layer has a pH of 5.5. Outside the southeast clay becomes too nuetral, mainly because less humidity and rain fails to leach away alkaline soil components. Thus we would never use gypsum, a sulphur bearing material, instead we use dolimetic lime, where magnesium is desirable since it too leaches. We would never use sand. The clay particles fill the voids in sand and makes a concretious material that becomes so hard and impervious to rain and oxygen that it would fair to describe the result as a lunar landscape. Heat resistant fescues such as Titan rX are used here, as heat is the biggest killer of grass in the lower transition zone.

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I'm in heavy clay country. My yard is too big to do this, but if you have a smaller yard, I recommend Aerating in the spring, putting down compost and/or sand, and use something like a piece of chain link with a weight on it to scrape it across your yard and fill the aeration holes with it. This can amend your soil without tearing up your whole lawn. A guy at my work says they do this with sand at the golf course he likes to play at. I'd go with the compost for a yard, though, because I saw on TV that when they built the arenas for the FEI equestrian games in Lexington, they used clay and sand to make a super hard base for the arena.

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There is a product called Earth Rite and another called Mushroom Stuff. Earth Rite actually breaks down clay soil. It breaks down clay, and increases drainage throught the soil.

I have used it a couple of times now. Once in a flower bed that was pretty much solid clay. Follow the label direction to treat your yard and treat early spring, summer, and late fall. Within the year, you will notice better drainage throughout the yard, increased grass growth, and gradual improvement in the texture of your soil.

In a perfect world, as noted, several cubic yards of top soil would be ideal. That isn't always an option.

With Earth Rite, you can also spray the front yard 1-2 times a year, and then anytime you notice ponding of water in the yard. Even though your sod is doing well, if there is an excessive amount of clay, it will not maintain more than a year or two.

When you seed, consider seeding as the first snow is falling. Then again in early spring, spot seeding anyplace that is coming up thin, scraggly, or bare. In the spring water Mushroom Stuff in as directed on the bottle, it will help the new grass root, and root deeper before the summer heat.

We drought terribly here during the summer. There is a drought tolerant BlueGrass mix, I believe it is either TriStar or Scott's. I have had the best luck with Blue Grass Fescue blends for grass in hard pack and clay areas.

The other option is to add "Field Conditioner" which is essentially a Gypsum blend as discussed in earlier responses.

I would start with Earth Rite first. Just don't spray it around any ponds. Earth Rite has been known to drain ponds by breaking down clay.

Follow up bi-annually with a weed and feed, and thin layers of organic material such as mulched leaves, manure, worm castings, cotton burr compost, etc. You don't want to bury the grass, so you may have to add thin layers a bit at a time over a couple of weeks. I use straw as well, but that is due to high traffic in my back yard (aka 260 pounds of dogs running across it packing everything down). For us, the straw gets ground in and doesn't cause an issue with thatch.

Do not mow your grass for a "final" mowing of the season late in the year. Let it get long enough to go to seed before winter sets in. It will seed itself that way. We allow our back yard to go to seed every late fall/winter. It helps to increase density AND it is reseeding with the healthiest strains of grass that grow well in your yard.

A year or two? You'll forget you ever struggled with a patchy, scraggly lawn!

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