Clay soil problems

destanyApril 5, 2004

Hello, I'm new here, nice to meet you all!

I was wondering if anyone has any advise on treating my clay type soil. Last year wasn't so bad, I spent hours breaking up the clay and mixing it with sand, coffee grounds, rotten veggies, etc. It was a process that took three months. The marigolds, allysum and sunflowers did great! (marigolds got up to four feet and blooms so big they broke the stems, cucumbers I couldn't keep up with). I left the garden to spoil in autumn for this years fertilization. The clay is worse than last year! This year I'm wanting to do a bit more permanent as I'm using perennials and annuals both. Hollyhocks, larkspur, mallow, pennyblacks, soapwort, scabiosa and trusty old allysum. Some of these will do fine in clay, but some need good drainage. Any suggestions? I didn't think I needed to treat the soil this year and it's a little late for rotten veggies...


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sawdust. more coffee grounds (I put out a collection bucket near the pot at work, some people hit their local Charbuck's up for their grounds) perlite. buckwheat hulls. rice hulls. peatmoss. triple ground mulch...

and rent a rototiller... till. spread out a tarp. move all that tilled dirt to the tarp. till again. repeat if you have the strength/time. add soil amendments. till with bottom layer of soil. cover with 2" of dirt from the tarp. cover with 2" of amendments. dampen with hose. repeat until you run out of material, and have a nice mound where the bed was.

    Bookmark   April 5, 2004 at 10:42AM
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Don't add more sand. Everyone here has told me w/ my clay soil not to add sand, it makes it worse unless you add lots and lots.

Keep adding organic matter. This will be a continuous procedure. I get free cedar mulch, as much as i want, and i'm just dumping it on every year (takes along time to break down tho). In some places, that have had mulch and leaves for about 7-10 years, the soil is great. Too fertile for my natives to grow in!!! But the "imports" love it, and do great.

    Bookmark   April 5, 2004 at 1:13PM
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morz8(Washington Coast Z8b)

Destiny, I'm gardening on a clay base too and it's an ongoing process, no treating it once and thinking the problem is solved. Now that everything is so heavily planted, I top dress (mulch) with compost in Spring and Fall, and each time I take out a plant, or add one, I work in more compost...anytime the ground is open is an opportunity for getting that organic matter into the soil...the following link has the perfect recipe for amending clay...just keep up with the compost and make it one of your annual chores just like weeding. (available by the bag or truck load if you have not made your own, and the composted steer manure that Home Depot has been carrying for just under $1 per bag is great quality for the price) Most home building supply stores will have coarse sand in 80# bags for less than $5...emphasis on coarse here.

Here is a link that might be useful: Gardening in clay

    Bookmark   April 5, 2004 at 1:14PM
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DrynDusty(z8 AZ)

I've been adding organic matter to my soil for 16 years, and use mostly cow/horse/sheep manure: as many as 7 truckloads one year. It was all gone at the end of summer. I mulch with alphapha hay because it's available. It has more nitrogen, so it rots fast and doesn't depleat the soil of nitrogen like straw or sawdust will. We compost everything at the end of summer or early spring. Lots of blood meal, rock phosphate, whatever we can get.
The soil is still rock hard about 9 inches down, so I have a nice bonsai garden!

    Bookmark   April 5, 2004 at 5:46PM
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Thankyou all for your great advise! I live in MO so clay is a fairly common problem out here. Most people I know dig it up and replace it with bags and bags of topsoil. But I don't have that kind of money.
I tilled and tilled today, the old garden was good and composted, so that'll make a nice organic addative, plus, I also had last years mulch that I was just going to throw out. I put that in there too, as well as my whole winter supply of old coffee grounds. I was saving it to mix with topsoil for continuous fertilization. I just mixed it in. I also, believe it or not, had a big bucket of sawdust left over from the toybox we made the kids last fall. I knew there was a good reason to hang on to it!

Now, one more question: Should I go ahead and seed now, or should I give it a week or two to settle in? I'm direct seeding, so I don't want to wait too long.

Thanks again for all the great replies!

    Bookmark   April 5, 2004 at 7:17PM
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Why not just grow plants that are happy in clay? There are lots of books out with such lists? Seems alot easier to go with the flow than to fight it?

Borders Books has some plant books in their bargain section that has chapters on clay planting. A good book is, "Right Plant, Right Place (Gardening Essentials) by Jackie Matthews"


    Bookmark   April 6, 2004 at 12:58PM
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morz8(Washington Coast Z8b)

I think I'd wait a little, if you 'tilled and tilled' you've fluffed it up pretty good and it's going to settle. You may even want to water it down well, let it dry out and take note of how it might compact if you are not having rain. You can find people who wouldn't even use a tiller in preparing a bed, my father in law for one, who wouldn't use his gift tiller as he said when the soil settled it became too hard...preferred to double dig.

Are you certain you've got all the amendments into your soil that you are going to need...I can't tell from what you tilled into the soil if it would have made a deep layer over the entire area before tilling. The time to prepare the bed for best long term results if you are planting perennials is now, not after they've been planted...think $.50 cent plant in a $5 hole, the best gardening effort is put into the bed preparation, it's not an area where you can cut corners....

    Bookmark   April 6, 2004 at 1:40PM
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meldy_nva(z6b VA)

Try adding some gypsum. You should be able to find it in the gardening section of HD or at a large nursery. I tried it out several years back: 1/2 of new bed with just compost and leaves worked in, and the other 1/2 with same amount of leaves and compost *and* about 25 lbs gypsum (over approx 8'x16' area). It worked very well in loosening up the clay and that side of the bed still has better drainage and tilth than the other side. If it works on my Va clay, it should be able to help your clay :)

    Bookmark   April 6, 2004 at 1:59PM
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I think Angie is getting mixed up about sand.if you use buiders sand[soft sand] it does make matters worse as soft sand almost has a fine structure like clay
If you use sharp sand[the TYPE used in concreting] which is very coarse it will definatly improve your clay soil.
I put about 3 inches of sharp sand at least on my clay for years and dont dig it in,just incorporate in the top 3 inches.I now have a first clas clay soil is a very fertile soil.
My friend who was market gardener like my self used to ask the driver of the local council to tip the burned ash from the incinerator on his land,He put about 9 ins and rotovated it in after a couple of days the smell soon disapeared and after a year he had the most beautiful soil I have ever seen.personaly i would not put it on edible plants
Best wishes

    Bookmark   April 6, 2004 at 3:23PM
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morz8(Washington Coast Z8b)

Colorado State University Extension Ag. Office:

"It's easy for Gardeners to become frustrated with hard, clay soils and to try anything that sounds like it may work. The belief persists that adding gypsum can break up compact clay soils, but this is not true. Loosening soils is a physical process, not a chemical one. Tight, clay soils are loosened by mixing in organic amendments, or organic materials. The amendments hold the clay particles apart, creating more space for air, which is critical to root growth."

    Bookmark   April 6, 2004 at 3:32PM
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Thanks again, those are all great ideas. I agree, I think I'll wait a week to let it settle and break down a bit, just hoe it lightly before I seed. I'm sure I've got enough organic mixture in, it's basically the same set up I had last year minus the vegatables, but the mulch, sawdust and other stuff should make up for that. There was about four inches of organic, and a good amount of sand in the ground from last year. I'll use a storebought fertilizer for added nutrients, and I'll see what my store has in the way of things I could put in before I seed.

    Bookmark   April 6, 2004 at 3:33PM
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PeterB_NZ(South Is. NZ)

organic matter, organic matter, organic matter - along with amendments such as very coarse sand, and gypsum. In my experience there isn't any single "silver bullet" solution, it's just a challenge which will be ongoing. Amendments such as sawdust are OK but much better if they're composted or rotted down. The objective is to create conditions where earthworms will want to live - their tunnels will then create the aeration and assist drainage of the clay. Don't expect perfect solution overnight and consider it your long-term project(the cross you must bear for daring to tame a clay garden!) - so treat the whole area as best you are able within your budget each season. Make sure to dig over-generous holes for the rootballs of your new plants, and work a good measure of a commercial compost into the immediate vicinity of each plant so the plants have a much more hospitable "intermediate" environment to expand into before they encounter harsher amended clay environment.
good luck, Pete

    Bookmark   April 7, 2004 at 4:58AM
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meldy_nva(z6b VA)

There are numerous reports and articles regarding the research on the use of gypsum as an agricultural soil amendment (including many done by Colorado U). However, while admirably informative from a chemical/technical standpoint, most reports address only one facet of gypsum's effectiveness - in alkaline soil *or* in acidic soil *or* in remedying excessive salts in soil, etc.

I did find a report written in [mostly] plain English by a chemist/agronomist which seems to summarize most aspects of the use/effectiveness of gypsum. Last revised in April 2001, so it's fairly recent. Link attached. Please note the paragraphs regarding soil crusting and soil compactation - major problems faced by those who are trying to garden in clay soil.

I would suggest that you read this summary and possibly a few more articles; and then (IF you have clay soil) do as I did and conduct your own comparative experiments! I would enjoy hearing from you after you have results from a careful side-by-side comparision of a garden site both with and without gypsum amendment.

Here is a link that might be useful: Summary re gypsum as a soil amendment

    Bookmark   September 1, 2004 at 7:54AM
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To help keep my clay soil open and loose, I add small-grain granite chicken grit, along with the usual copious quantities of humus, homemade compost, leaf mold, etc. I also throw some grit in when I'm mixing up potting soil, especially for bulbs that like good drainage. My local Southern States ag supply store carries it---I can buy it by the pound (@$.23/lb) or a 50-lb bag ($6.99). It's also called 'growers grit.' Seems to work even better than coarse builder's sand.

    Bookmark   September 8, 2004 at 9:17AM
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audmendousg(z7 central TX)

I've heard gardeners talk about using pea gravel to loosen clay, and the A&M gurus here in Ts. suggest 3 in. of organic matter and 3 inches of expanded shale tilled into the soil. I use lots of compost and have tried a little gravel this year, but haven't found any of the shale to use. Hope this helps.

    Bookmark   September 11, 2004 at 10:24PM
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sandy0225(z5 Indiana)

We had this problem with our new septic tank builder putting all the subsoil back on top of the septic fingers, and it was straight clay. We tilled in a lot of peat moss the first year and it helped, then the second year we tilled in a couple truckloads of horse manure. It's a lot better now. Keep putting organic matter in there.

    Bookmark   November 17, 2004 at 2:04PM
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Gypsum works very well to break up the clay soil initially. I use it just so I can get my shovel into the ground! but then you have to add new topsoil and compost - to get mine in good condition it usually takes a full season before planting. OR you could just do raised beds....

    Bookmark   December 7, 2004 at 9:57AM
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Flowerkitty(Z6 or Z5 SE MI)

I read the linked article on gypsum. This might help me because I not only have waterlogged clay. My property is lower than the road by my home. The city dumps huge amounts of salt in winter, and the street drains onto my land as we dont have storm drains. That article implies gypsum might help make excess sodium leach out of the soil. Thank you for all the posts. I am copying out all the suggestion

    Bookmark   January 7, 2005 at 11:30PM
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uber_mann(z7b DFW-TX-USA)

"Expanded" shale. Apparently the best technology has to offer now is shale which has been heated to the point of fracturing. Your local bulk compost/mulch/dirt provider should carry this stuff.

I know there is such a thing as "shale oil" which is simply subterranean oil in shale rock. The implication is that shale is permeable by fluids, and this jives with the shale propoganda which claims that it both promotes drainage, yet retains moisture.

Our local garden shop pro was telling me that we will all be using shale exclusively in a few years as it's miraculous capabilities become known...

I have used some (it is expensvie if not purchased in bulk) and, indeed it appears to be the silver bullit for my incredibly dense black clay.

    Bookmark   April 4, 2005 at 10:55AM
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My garden is Western colorado clay soil. I use a great deal of compost,soil pep,soil conditioners . Add handfuls everytime I plant. Never work the soil when it is wet. Our extension office does not recommend adding sand to Colorado soil it makes it more heavy . Add vermiculite or perlite to areate the soil. I would suggest you visit the web site for your local extension office and read articles about you soil.

    Bookmark   April 18, 2005 at 8:34PM
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Does anyone know where to buy expanded shale in Maine? i live in the Bath area and would love to find a source.

    Bookmark   February 13, 2008 at 4:42PM
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I can't believe nobody has meantioned LEAVES!
In my area they are not only free but overly abundent!

My last house had soil so hard I had to use a pick to first break it!
I bought a leaf shredder at a yard sale and ground up the leaves as small as possible and started mixing it into the soil on a regular basis. (I also added shredded newspaper)
After a year and 1/2 to two the soil was so soft & loaded with earthworms I didn't even need a trowel to dig a hole to plant.

    Bookmark   March 5, 2008 at 3:57PM
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I have also read that a lot of gardeners have had tremendous success in areas where there are copious leaves. They say that by adding a good 8-10 inches of shredded leaves in the fall, and then tilling them under in February, their soil is just like what you find in the forest. Loamy! I am going to start using this method this fall in addition to my compost mulch during the growing season. I'll let you know how it goes.

    Bookmark   May 14, 2008 at 3:31PM
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I totally agree with the leaves and compost. I live in the Willamette valley in Oregon where the soil is almost solid clay and rocks! My husband and I have just had to put lots of elbow grease into it the last 3 years, but we are finally starting to see the difference. There were times of frustration where my husband would just take chunks of the stuff and haul it in a wheelbarrow to the bog behind our house. I realize not everyone can do that, of course! In addition, we did "cheat" and have also bought several cubic yards of planting soil which is quite cheap here. We just keep working it all in. The best mulch I have found so far is leaves. We have a beautiful vegetable garden (well, apart from some early blight because of the prolongued cold weather), flower garden and our lawns are so luscious that walking barefoot on them is a pleasure. It has taken about 3 years though, so patience is a must! We still find spots of clay, but we do work it in with other soil and that seems to be the trick. Most of the plants that are indigenous to the area can handle a bit of clay, I have found, including roses, azaleas, rhodies, daphne, evergreens, hosta and many many other plants and flowers not indigenous. One more thing, I have found that mosses like Irish and Scottish mosses if carefully planted especially in a flower garden can be not only fragrant and beautiful but also help amend the soil.

    Bookmark   June 13, 2009 at 7:54PM
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Sounds like expanded shale is the ticket in North Central Texas. Has anyone found a good place to purchase it - NOT by the truck load?
Thanks, I'm new to this site and am loving the information available I never had before!

    Bookmark   February 1, 2012 at 1:59PM
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I used leaves for years until the cities around me told the residents to stop bagging the leaves. They are now putting them in piles and they get sucked up with a big street machine.

I've found an alternative to the leaves though that is easier for me to do. I researched the nutritional analysis of decomposing leaves and decomposing newspapers and they were virtually the same.

I'm ripping the newspapers in shreds and burying them and NOT rototilling anymore. Truthfully, the tilling had gotten to be too much for me as I've gotten older. The results are impressive with both leaves and newspapers. I like the newspapers though because it's like a hobby to me now. I keep bringing home stacks of paper from work and sitting right down on the ground while shredding and burying. It's oddly therapeutic LOL! The worms LOVE the newspapers and are making the soil airier and browner- instead of heavy, sticky and pink-color like it used to be.

    Bookmark   April 4, 2012 at 5:14PM
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Please do some research on-line for a product called "Aerify." We purchased it when confronted with black gumbo, that when tilled looked like big black rocks. After using this product, we were able to get it broken up enough so that we could plant our daylily seedlings. We live in another place now, with a cement-like clay sub-soil. I may start using it again.


    Bookmark   November 1, 2012 at 3:24PM
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zeak8892(zone 6)

I have a large yard with hard clay soil that stays soaked after rain making it tough to mow. Much of the yard is grass, so digging it up and amending it is impractical. I've seen people talk about the benefits of worms so I had a thought. What if I just added a ton of worms to my yard and let them burrow down and do their thing? If so, is there a certain type of worm like the ones I use in my compost bin? Thanks.

    Bookmark   October 25, 2014 at 11:56AM
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