clay type soil

natalija_gardenerJune 23, 2010

Has anybody had clay soil and what worked best for you to improve it?

I was trying to improve it last fall using Tagro compost, it had a lot of worms this year, but it did not help much with clay soil- when it dries it has crust in many places. I guess that was the reason why many seeds I put did not sprout - including watercress, cucumbers, yellow crook neck squashes from Territorial. Other seeds did sprout o'key.

There is a lot of advise about how to improve clay soil, but what worked for you personally?

I really appreciate your help.

Thank you for reporting this comment. Undo

I've been improving clay soil with coarse sand for the last 1 million years. (Feels like it anyway) If your soil is a clay loam that supports weed growth, sand will work. Till the soil as deep as you can. Add one inch of coarse sand on top. Till deeply. If the soil still gets hard on the surface or cracks when it dries out, add another inch of sand. The beauty of sand is that it is an immediate and permanent fix. Don't blame me if you're stingy with the sand and it doesn't do anything. For a big area, you really need a rental tractor with a bucket on the front and tiller on the back, or you'll end up crippled for half the summer. It's heavy work.

If your clay is the smelly impenetrable subsoil variety, forget it. You'll have to buy some good topsoil and pile it on top, or replace the clay with it.

For soil science background, google "soil triangle".

If you don't believe me, or are terrified by all the gloom-and-doom stories about sand, just buy a bag of sand at Home Depot for $3, and try it in a small area. Decide for yourself. If you live near Kalama, WA, you are welcome to visit my "estate" and I'll show you a before-and-after soil comparison. You won't believe how nearly everything will grow like mad in a well-aerated loam or sandy loam. And many of those mysterious problems with losses over the winter and so forth will just disappear. This is not to say that clay loam is evil, but for gardening, I much prefer a lighter soil.

Once you turn your soil into a loam or sandy loam soil by adding sand, now you can go for perfection by adding lots of humus. Bboy will tell you that a surface application of humus is more natural than tilling it in, which I agree with, except that decaying roots also add humus under the soil surface in nature. Anyway, I've always tilled some decayed bark in with good effect.

Once I do my initial soil improvement, I generally don't till ever again. I just keep the soil surface mulched.

If you have a problem with a high water table, soil improvement will not help you. You need to drain the water away from the garden. Then improve the soil.

    Bookmark   June 23, 2010 at 11:53PM
Thank you for reporting this comment. Undo
Embothrium(USDA 8 Sunset 5 WA)

Operative term "small area". A small amount of sand cannot make a dense soil open without the finished product ending up with a high enough proportion of sand. Many quite dense soils already have a sand component, showing how a small amount of sand is not enough to prevent them from being dense.

This existing proportion of sand plus the sand you add is the final sand component the soil you dig it into ends up with. If there happens to be enough sand already present to make the finished content adequate, then a satisfactory result can be realized. Otherwise, you always have to add enough to achieve a certain minimum percentage of sand before the overall texture of the amended area changes.

Elbow grease is so much easily and reliably applied to spreading good topsoil over the existing soil and planting in that, without any mixing involved.

    Bookmark   June 24, 2010 at 12:55AM
Thank you for reporting this comment. Undo
Belgianpup(Wa/Zone 7b)

Don't waste your time, money, energy and frustration. Build some raised beds and fill them with decent soil and compost.

One of the problems with clay soil is the drainage problem. You can add tons of sand and compost, but you're only adding it to the top (even if you're working it in a foot deep). Under the improved soil is more clay. All the moisture that sits on top of the clay layer just resembles an in-ground swimming pool with really thick water in it.


    Bookmark   June 24, 2010 at 2:00PM
Thank you for reporting this comment. Undo

Belgianpup, that's why I separated out the issue of bad drainage. I've done gardens in NJ, CA, OR, and WA with sand. It works great. Are you saying that your method is the ONLY good one? Natalija can use sand and compost to turn her clay into good topsoil at a tiny fraction of the cost of purchased topsoil. But it's more labor. On the other hand, when you buy soil mixes, you never know what you're going to get. It's kind of like cheap potting mix. Some of it won't support plant life. So it's her choice. I use sand to improve large areas where the cost of purchased topsoil would be prohibitive. Once you do it, you suddenly realize that you can "tune" your soil for different plants by adding more sand. For carrots, add a lot of sand to at least 12" deep, and get straight long roots. For some desert and alpine plants, grow in nearly pure sand, or they will rot out in winter. Coarse sand also makes a good mulch for many small plants, and makes it very easy to pull weeds.

On the other hand, if you don't have time, or if you don't have a tiller, or if you just want a few square feet of garden for some veggies, raised beds and purchased topsoil will get you going with almost no effort.

Use your own judgment, and do what's right for you. Think about this: if you go ahead with the sand method and mix it in by hand, you can drop your gym membership for the summer. More savings!

    Bookmark   June 24, 2010 at 7:06PM
Thank you for reporting this comment. Undo

Well I'm not here to pick a fight with avid proponents of sand, but I found that a high quality compost such as from Cedar Grove greatly improved drainage/aeration and overall quality of my clay soil in Olympia when applied to the surface at a depth of 4-6". In this situation I had clay subsoil as well with hardpan in some areas, but that didn't seem to be a big issue as long as I didn't try to grow anything really finicky. Unless you live in a swamp, having a poorly draining subsoil (if indeed you do) isn't going to stop you from growing vegetables because by the time it's warm enough in spring to plant anything, things have usually dried up enough, or nearly so, to accommodate most new plantings especially if you have added compost. You need to give said compost at least a few months (i.e. over the winter) to allow it to break down sufficiently, and if you do that you don't need to dig it in. One wonders why "when it dries" is a concern when a vegetable garden usually needs quite a bit of water in our climate, especially when seeds are germinating and just starting to develop. You might also consider cover cropping over winter which a lot of commercial farmers are now doing. It ought to help somewhat over time.

    Bookmark   June 25, 2010 at 2:34AM
Thank you for reporting this comment. Undo
dottyinduncan(z8b coastal BC)

A few years ago, our local Rotary club had a fundraiser selling feed bags full of chicken manure mixed with sawdust. I bought all I could fit in my car. I couldn't believe how much this stuff helped! I used one bag in a small flower bed and the next spring the shovel slipped in like a hot knife through butter! What a delight when you are used to dealing with heavy clay soil that dries out to a hardpan. Now, likely 5 years later, this little bed is still fertile and loamy. It was a good lesson for me and I just wish I could buy more of this stuff. It's the handling and transportation that is a problem. The feed bags full were great but I think that was a one-time thing.

    Bookmark   June 25, 2010 at 9:38AM
Thank you for reporting this comment. Undo

Has anyone in the PNW heard of a hoe?
Growing up on a farm in Ohio, we had clay soil.
It dried up into cracked sheets in the summer if allowed.
We were out there constantly with a hoe between vegetable rows and in and among flower beds not only to keep down weeds but to keep the soil loose.
I'm sure a mulch would also have helped, but it wasn't used back then. I guess a hoe kept us kids busy and out of trouble.

So is there some kind of difference in the type of clay?
Clay holds moisture and nutrients that my sandy gravely soil here does not.
I do know there was not hardpan beneath anything there.

    Bookmark   June 25, 2010 at 11:23AM
Thank you for reporting this comment. Undo
botann(z8 SEof Seattle)

When I was a kid on a farm north of Spokane, I used a hoe a lot. We also used a hand cultivator that we pushed up and down between the rows. We used dust as a mulch. It broke up the capillary action and prevented the moisture from wicking out of the soil.

I contour clay soil as much as possible and add as much organic material as it will accept by tilling it in and adding it on top after planting. Drainage is very important from the downspouts the the lowest point on your property. Sand and clay by itself adds up to stucco.
It's mainly the organics that make clay workable. You have to add a lot of sand to make it more sandy than clay-like.

    Bookmark   June 25, 2010 at 12:06PM
Thank you for reporting this comment. Undo
dottyinduncan(z8b coastal BC)

My clay soil gives me about a 20 minute window between being heavy, wet soggy to solid as a rock. Yes, I hoe, add compost, peat, manure -- anything organic I can find and still have lots of areas that are useless. I dug some potatoes the other day and the soil broke apart in chunks 6 inches or so square. The best veggie garden I have is a lasagna garden. A couple of years later, it is still producing good veggies. I've already harvested a couple of cabbages, spinach and some snow peas (they are over 6 feet high now). Natalji asked for help especially for germinating seeds. This type of soil is awful for small seed germination. Perhaps she would be better using some potting soil in the area she is planting the seeds.

    Bookmark   June 25, 2010 at 12:47PM
Thank you for reporting this comment. Undo

You wanted to know what has actually worked -- so this our experience on our rocky, orange-brown clay. So much clay that our kids used to mold objects out of it letting it bake in the sun. Yes, the slimy when wet and rock hard when dry clay.

Nothing new really, just organic matter in all it's forms -- whatever is green or brown, non-contaminated, & free. Takes time to build it up...

Over the years we've added:
-Starbuck's coffee grounds (stop by, call ahead, whatever it takes, more volume in winter as less gardeners pick up, more to be had if you call ahead & say you'll come by 8pm closing... Line trunk w/ shower curtain to protect it as bags leak.)
-fruit & vegetable trimmings
-garden waste
-manures usually with bedding (chicken, duck, rabbit, horse)
-leaves, mostly maple & alder, some oak
-grass clippings, very thin layer (see through layer) or -dried on tarps 1st
-feed store's barn sweepings (hay & straw mix, sometimes wet, sometimes dry - some sprouting of seeds, but rake/hoe & cover w/ next layer - no problem for us here)
-paper, a brown (newspaper, scraps, junk mail, kleenex, napkins, tp tubes, cereal boxes, paper sacks from take out, etc. I collect the paper in a paper sack then have my guys tear up while watching TV.)
-coir (coconut fiber) $.99 a compact bale at Top Foods end of season closeout like November. Only time I've bought compost material... Used mixed by thirds with potting soil & compost for potting on transplants and starting seeds. Held lots of moisture, so worked great and technically, I haven't used it as compost ingredient. Not yet anyway.

All layered on top of the rocky clay soil...
After awhile it is deep enough to plant in, so...

If composted, layer on or dig in with a garden fork just a little. I don't rototill or do any heavy digging due to fibromyalgia and previous back/neck injuries.

If fresh manure or uncomposted, I use as mulch letting the worms do the work over time. Just keep the fresh manure away from plants during the growing season. I've put up to 12" of matter partially composted manure on a bed in fall/winter. Forked it up a bit in spring, planted transplants & mulched, or seeds and waited to mulch.

Also, pile large piles behind trees, shrubs so not too ugly while I wait for them to compost. Used to create pallet compost bins away from garden, but easier to pile it where you'll use it just rake or fork it a short distance. I scoop with buckets when it's fairly dry & that's easy to move, too. Nothing too hard or heavy for me...

Applied regularly any form of organic matter will make a difference in your soil. It just takes time. Early on I focused on some pockets instead of spreading all of it and just didn't have enough volume as I had a small compost pile and a worm bin for food wastes.

Two springs ago, my husband & son brought horse manure by the trailer load. More came in last fall/winter as well as early spring, so now it's one large garden all along the driveway bordering the forest. Instead of rocks at edge, we placed CMU concrete pier blocks along 2/3 of it as that's all the blocks I'd gathered off Craigslist over winter. This area slopes from forest to driveway as the soil was scraped away as fill at one point. With the blocks in place it is more level & gives more planting area (though less driveway width...) We mixed up some gritty potting blend for the holes...6 filled with chives, 2 oregano, 2 thyme, 2 other: hen & chicks, armeria, creeping zinnia, creeping phlox & planted 2 rows of everbearing Ozark Beauty strawberries behind. Hundreds of strawberry plants from our original 2 4" pots 8 years ago.

Rocks, rocks, rocks, pulled out as they surfaced or when I was energetic dug them out. Used to line the beds along the driveway, but this spring we've moved most or it to the front yard for a 3' wide x 50'+ path with patio block remnants as stepping stones. Our idea was to create a area for our excess rain water as we've also dug some dry wells filled with rocks along the path.

Books may tell you to apply 2-4" of organic matter, but amount all depends on what you're applying & what your soil consists of before you begin. Too much compost is said to rot your seeds or roots; however, that hasn't been our experience. I attempt to get a mixture of sources & apply dolomite lime every 3rd year and calcium carbonate powder yearly in the fall or even in spring if I've forgotten if I've applied it to that pocket or not. I don't do a lot of it using a yogurt cup as a scoop to sprinkle like a child would sprinkle cookies a bit thick, but not covered then fork it in a bit or just layer on more mulch...

This past winter we began a lasagna garden for an ornamental border. Regular applications of whatever greens & browns I gathered were layered. So far, we've had great results there and there is rocky clay under the grass under the cardboard under the organic matter. However, I didn't plant any seeds, just transplanted plants.

Also, have covered compost piles and lasagna gardens in progress with feed store sacks, old carpet upside down, used black plastic bags, burlap bags, old curtains or blankets, etc. Use rocks to weigh down the corners & easily lifts up to apply another layer.

I estimate that we've added over a ton of Starbuck's grounds to our beds over the past few years. Some mixed in compost bins, but most as mulch slightly mixed in with a 3- pronged fork. Over wet cold winters I just dump the grounds out of the bags & use a stick nearby to spread it out a bit letting rain & worms work it. I try to put it behind plants & pull it forward after awhile. In strawberry beds I usually apply shredded leaves in the fall, along with 2" or more of coffee grounds mixed together slightly. Then add coffee grounds all winter through January or so, strawberries come out of dormancy right up through the grounds. I apply another type of mulch after they're at least 4" tall (shredded leaves, chopped straw, or thin grass clippings).

I didn't do this all at once, but over the past 17 years... season by season.

If you're in a hurry--
-do the pockets
-okay to use fresh rabbit & alpaca manures (We have 2 rabbits for pleasure & fertilizer, but I once picked up 10 huge heavy bags from a meat rabbit raiser...that stuff was potent, but amazing!)
-get volume ( manure - old Rodale Org.Gardening states horses excrete 18,000#s annually - includes urine. Now you know why horse owners beg you to come get it... especially if they stall their animals.)

Pile a huge amount of horse manure/bedding mixture 4x8x3'if you can, mix w/ browns, coffee grounds, a few shovels full of soil and/or unfinished compost from another pile, cover, keep moist, turn it every 2 weeks while it continues to heat up maybe into September & you might be able to apply this fall, but for sure by spring you'll have black gold! I've done this for the past 2 years and that compost is fabulous stuff smells like crumbly, moist dirt.

Another idea that has worked for us is to plant directly into straw bales. Google it for details or I can post what I've gathered if you're interested. It's our 2nd year of planting tomatoes in them & will be the last for these bales that are on the edge of the forest undergrowth. I wanted to plant a large amount of tomatoes and didn't have enough good deep pocket areas last year, so the bales to the rescue. Free leftovers from our church Live Nativity :o) Call me cheap or just resourceful, I don't mind at all!

Hope that all helps--

    Bookmark   June 25, 2010 at 4:26PM
Thank you for reporting this comment. Undo

Thanks to all of you for your time and advice! A lot to think about. I do grow nursery bought seedlings o'key, but the main problem - growing from seeds + poor quality of root veggies. some seeds doing fine - redishes, greens. So reading all your advice I will come up with something for next year.

    Bookmark   June 25, 2010 at 6:36PM
Thank you for reporting this comment. Undo
reg_pnw7(WA 7, sunset 4)

Root veggies in clay! no wonder you're having problems. You'll want raised beds for root veggies. And direct seeding is bound to be a problem too. I start most everything indoors in seedling trays, except things like beans and peas that always germinate well and strong.

My secret to working with pottery-quality clay soil? constant additions of organic matter, and mulch in summer to prevent the cracking. Use drip irrigation and make sure you run it long and slow enough to soak the soil a foot down with no runoff. Clay absorbs water slowly, but it also dries out slowly, so you won't have to irrigate very often this way.

Adding 'too much' organic matter isn't so much a matter of rotting seedlings or something, it's more a matter of your soil subsiding as the large volume of organic matter decomposes and becomes a much smaller volume. Not such a problem in annual vegetable crop areas where you can add more every year. More a problem in lawns and perennial beds where it's harder to add sufficient compost every year to keep the soil volume up. A good rule of thumb to keep in mind is that 20% by volume of organic matter is a LOT. When you get up into the 40% by volume range you no longer have a mineral soil but an organic soil, which is nice so long as the organic portion is decomposed and not just raw leaves and twigs, but it will subside as the organic matter is used up. Soil 'eats' organic matter just like plants use nitrogen and we eat food, so your soil will need regular additions of organic matter.

    Bookmark   June 27, 2010 at 12:42PM
Thank you for reporting this comment. Undo

"your soil will need regular additions of organic matter"

That's one thing I love about the sand. Once you mix it in, you're done. It's permanent. Why are people so uptight about this? It's such a pleasure to garden in sandy loam soil. I can dig holes with my bare hands in soil that I improved 23 years ago. Life is too short to muck about in clay. No, I don't own stock in any sand companies.

    Bookmark   June 27, 2010 at 3:51PM
Thank you for reporting this comment. Undo
Karchita(WA Z8)

One word: Compost

    Bookmark   June 28, 2010 at 1:19AM
Thank you for reporting this comment. Undo

I agree: One word:


    Bookmark   June 28, 2010 at 7:10PM
Thank you for reporting this comment. Undo

Well if you add so much of anything that the roots hardly reach below a really thick top layer, then it only has to be done once. At my place in Olympia I watched clay "eat" sand as fast as it "eats" compost and with the compost the soil came out more fertile in the end. So I think that compost need be applied only once, as long as it is good quality and applied thickly enough to begin with. as long as your general gardening practices don't take more from the ground than you return to it. Cover cropping is an important part of this and you should really do it if you have sand (imported or not) even more so than clay since sand has a much lower nutrient holding capacity.

Here's another wild idea. One gardener in Gardiner (how about that) spread 18" of wood chips over his whole garden and let it sit to decompose for a couple years. He plants (mostly starts, not seeds, I think) right into it with excellent results and adds an inch or two of wood chips every year which break down to form more compost. He also never has to water despite rainfall being only about 20" per year. There wasn't much happening there when I visited in March but perhaps I can go back this summer (if it ever gets here ) and take some pictures.

    Bookmark   June 29, 2010 at 1:36AM
Thank you for reporting this comment. Undo
pat_tea(PNW, Van,WA)

Just wanted to thank Lilydude for the nice visit we had last night at his place in Kalama, WA. Yesterday I was searching GW for clay soil issues. Low and behold Lilydude had posted his sand solution and when I read he lived in Kalama, WA my eyes popped and I immediately emailed him. He lives 1.5 miles from me. I witnessed firsthand the wonderful results he has gotten from adding sand to Kalama's less than fine soil. I have read so much negative about sand in books and on line that I had never tried it. My husband has tried to convince me but I stuck to my guns; after all, the experts oppose it. After seeing his results my husband sweetly smiled and whispered, "I told you so". Enough said. This woman is a believer and I urge you to take Lilydudes advice and buy a bag of sand and try it for yourself. Of course, sand alone won't do it. You must also add nutrients. Thanks Lilydude for your advice and the tour of your gardens and greenhouse.

    Bookmark   June 30, 2010 at 3:27PM
Thank you for reporting this comment. Undo

I have had small-scale success with mushroom compost that I get from Mt. Scott Fuel in SE Pdx. It's not cheap ($35/yard) but it seems to a really good job of amending the soil. It also seems to be terrific for plant growth in general, I jokingly call it steroids for plants.

If you haven't, check out Gardening West of the Cascades by Steve Solomon. He has a lot to say about soil integrity and adding compost. Solomon says be wary of adding too much compost because of symphylans.

    Bookmark   July 19, 2010 at 4:16PM
Thank you for reporting this comment. Undo
Embothrium(USDA 8 Sunset 5 WA)

There are facts behind all anecdotes, that are not effectively changed by misinterpreting results. Again: how much sand is already in a given soil + how much sand is added determines final result. A certain minimum amount of sand has to be present before the texture of the soil is changed. All sand added before that point is reached will not produce the desired result. If a soil is heavy and low in sand content mountains of sand have to be paid for and dug in at great effort before the soil loosens significantly. And if you overdo it you can create excessive drainage and resulting issues with droughtiness and infertility.

When I wanted a looser soil to plant in I bought pit run sand from a nearby pit, dumped it on the ground, formed it into berms and planted. Got great results.

A little clay goes a long way, mixing amendments and sand with clay is working at cross purposes - you are taking those nice fluffy amendments and fast-draining sand and fouling them with greasy clay, that if mixed in thoroughly enough coats the sand particles.

    Bookmark   July 19, 2010 at 11:56PM
Thank you for reporting this comment. Undo

I have found the best result for my garden was to buy a truck load or two of good compost (which had a fair amount sand that I was worried about but now appreciate) and put it right on top of tilled beds and work it in a little with a pitch fork. At first I planted directly into that soil and there after I always have a bag or two of good compost on hand so I can add to planting holes of new plants. I usually get a couple yards of fine bark mulch to help keep weeds down and retain moisture.

    Bookmark   July 21, 2010 at 1:18AM
Thank you for reporting this comment. Undo
Embothrium(USDA 8 Sunset 5 WA)

Amending individual planting holes does not produce a benefit, this was beginning to be seen by researchers in the 1960's. Making special beds for small plants with small root systems, like rock garden plants, summer annuals or annual vegetables can work because such types can easily have their entire potential rooting area modified. Larger-growing, longer-lived plants would need to have a huge area prepared in order to be kept from encountering interfaces with different soils outside of the amended area.

And their roots are deep enough to end up in puddles collecting into the bottoms of amended planting holes dug out of damp clay soils.

If you plant intact field- or potting soil rootballs in amended planting holes then there are three different soil textures present for the new plant to endure and survive: the texture of the material the existing roots are in, the texture of the amended backfill and the texture of the soil around the planting hole.

Differences in soil texture affects how water moves through the soil.

    Bookmark   July 21, 2010 at 12:01PM
Sign Up to comment
More Discussions
Compost Bin Advice
After researching the costs of materials and help to...
Garrya elliptica won't flower
I am in zone 8 and have had a Garrya elliptica growing...
evergreens for by gate
I have a couple of Columnar Dwarf Siberian Dogwood...
What seeds r u planting now this early warm spring?
My arugula is up fine but carrots havent germinated...
Question re: NW Garden show
We are planning to go to the NW Garden show for the...
© 2015 Houzz Inc. Houzz® The new way to design your home™