This is a copy of responses posted on our FB page to two questions on clay soil. The questions were similar,so I only put one here.
It's kind of long, but every post had something to add.
Worth the read if you have a similar problem:
Gardening (in real life): Got clay soil? My FB friend Ed needs advice: I have about 15,000+ square feet of land. It's a front slope and a back slope. Clay soil. Nothing but weeds grow and once it gets hot it all turns to what looks like hay. What kind of plants can I grow on it? I want an orchard type of "garden" with fruit trees like when I was growing up, but what I've planted has died off. What can I do? Other than move to flat land. :/
Amend Your Soil
Denise: I used the "postage stamp garden" method of double digging & amending when I had clay soil. Worked pretty well.
Amy: Add sand and really work it into the clay. Then you have to add organic material...like compost and/or bagged top soil etc! The alternative is to dig out a foot or so of the clay and then put in good top soil on top of a layer of gravel for drainage.
Alondra: nothing like compost, sand and even more organic matter.
Sandra: Compost and expanded shale.
Patty: I live where we have a lot of clay...we do not recommend using sand at all here...as we say "Sand and clay are what bricks are made of."
Instead use 1/4 minus ten crushed rock (it has the fines washed out of it) 2 to 3 inches to the top 6 to... 8" of soil and 3" of compost to that and blend well. I mulch with a good grade compost or other organic material (not bark) so it continues to feed the soil. Compost added regularly will help keep the soil friable (so it has a nice crumb to it). Hope this helps.
Linda Susan: Lots and lots of organic matter. I sometimes lay cardboard down in sheets for a season and that really softens up the soil underneath for digging. I generally avoid adding sand and peat moss except in very small amounts. Vermiculite may help with drainage. The lasagna method of gardening works well with heavy clay areas.
Hanna: I have clay soil. Hard as pottery in the hot summer. I'm working on it by putting leaves and compost and anything which will break down. I will be putting the winter coop contents on it too. I've heard you should not let it lay bare. It can also be kept under cardboard or some other biodegradable material.
Sue: Add grit and organics. Peat, manure, leaves, coffee grounds. You need air moving through that fine clay soil. Add Gypsum, old wallboard works as well as the purchased bags. My father has some gooey clay soil and he defeated by truckloads of ...donkey doo and leaves. Turning it in a couple times a year. Stuff turns to hay once the spring water dries up and the water is no longer moving air to the roots. Suffocates them. By grit I mean sand with bigger particles to it. Pool sand, something that will allow air to move around.
Pat: Doesn't mention which direction the slope is facing and zone may be pertinent too depending on variety of fruit tree. Clay soil is a bugger, we have it here as well with the added bonus of MANY rocks! Although it can be worked with and I suspect there may be another reason coupled with the poor soil for the die off.
Roger: My home and work ,CSULB both have clay soil. Amend, amend, amend. When the Santa Anas blow it goes from moist to desert in hours! Roger Maxim At home I have raised beds ,lasagna style with purchased soil on top.
Kallie: I have clay as well, I started working small areas. I used raised beds and did the double dig method. There are cover crops that can help loosen the soil as well, but amending it is something that will have to be done. I took a biodynamic gardening class and they recommended "how to grow more vegetables and fruits than you ever thought possible" by John Jeavons. It talks a lot about how to amend soil, cover crops and double digging.
Michelle: Amend with organic matter. And also a product called utilite. It works miracles on clay soil. 1 small bag goes a really long way!
I found the book Kallie wrote of on discountbooksale.com ... amazingly low price too!
@Kallie what is double digging?
PS I also vote for Amend .... and coffee grounds, and compost
Pat: 15,000 square feet is slightly more than 3/10 of an acre. Amending the soiling will work but for that amount of area, it's going to take a LOT of input and will take time. Years, in fact. If you have years, I would recommend the use of cover crops all year round and constantly till under. Legumes will fix the nitrogen and also add organic material. Well rotted manure tilled in with the cover crops will work well too. Keeping the slopes planted will also help control erosion.
Rebecca: Sounds like my yard. I am interested in everyone's answers.
Wendy: there's not much you can do for clay soil. That's what we have. We just aerate it once a year and spread peat moss. After 10 years, the yard has improved but its still clay. We have raised vege gardens and use lots of mulch around the house where we plant annuals, perennials and herbs. We turn the mulch every year in those beds and add a little more each year and THAT made good soil.
Darwin: For fruit tree planting in any soil dig a hole three ft by three ft put muck or rich soil and mulch in the first foot then line the next 3 inch to 6 with rocks then fill the balance with muck and mulched soil your tree will grow faster and produce sooner
Kallie: @Katrina, micro and macro organisms live at different depths, so this is a method to keep the deep ones deep and the shallow ones shallow while loosening and amending the soil. Here is a link that explains the method well. http://www.appr...opedia.org/Double digging. it is a big job, so I have been working a few beds at a time. If you have really hard clay you may not be able to get down 24" the first time. This is far better for the garden ecosystem than tilling, because you kill of so many beneficial organisms when you just turn or till the soil.
I see there are lots of videos on YouTube as well. Here is an animation most of the videos seem to leave out the first step which is removing the first section of top layer. Here's another good video.
Lois: I have sand in No Fla, but ask anyone in Ga. esp. Atlanta. They are all clay and have gorgeous hilly gardens. Pink dogwood comes to mind...gorgeous!
Ryan: get a soil survey done by your local extension agency.......... Take about 15 plugs out of your yard with a soil core plug pulling tool and send those in to your agency.
Gardening- Adventures in The Dirt : When I asked about what to add to my clay soil (which is not 100% clay, only about 50%), I was told by the people at the garden center NOT to add sand or peat. Only organic material like leaves, compost, etc. The reasoning was that clay + sand + water = concrete. Apparently the peat can do the same thing. The person I was asking assumed I had 100% clay soil, so it seems like this would be better advice for Ed!
Kallie: I have also heard not to add sand to our local soil, which isn't all clay. You just can't go wrong when adding organic material.
Kieran: How deep is the clay? Can you have it removed by machine if you have a really big area? Or at least a percentage removed and then follow the tips above. I like the idea of big planters to at least have something interesting growing.
Ryan: Sand + clay = brick........ when put together in appropriate proportion.
I would imagine this means something close to a 50 - 50 match.
Peat has a very similar amount of pore space to clays because of its particle size..... it goes something ...like clay, silt, sand in terms of particle size working from small to large.
The Garden Growers: There's nothing like the nutrient value of clay soil, but the pH or bad water habits will ruin you. Plenty of peach and apple orchards in Carolina clay. Use compost and work to get those trees established the first year will give you a productive future.
Edmund: I agree with everyone on the addition of organic matter and lots of it. Gypsum is also good because it breaks up the clay structure a bit. I think the fact that it is on a hillside is an important consideration. Clay doesn't soak in very fa...st and if it just runs off, it doesn't have a chance. Re-shaping the land in a sort of fish-scale pattern with a bunch of basins can really help pond the water long enough to soak in. The organics will help it soak in quicker and deeper. I describe it in a bit more detail here. If you can get the water into the clay, it tends to hold onto it for a while. Also, once you get enough organics and get your trees planted, consider adding my corrhizal fungus. It will help your plants get all those great minerals from the clay.
Amend Your Gardenscape
Jaime: GJ, as an MG, I suggest building raised beds by buying soil. Usually this soil is river bottom and doesn’t contain many nutrients and it also needs amended. I amend my river bottom mounded beds with peat moss and I also add nutrients that I buy cheaply at the farm stores. a huge bag is 35 bucks and it will go very, very, far .I should also mention the soil we buy around her is also very alkaline.
Darwin:I have clay soil on a slope. What I do is dig out a trench three ft or four ft by three ft deep then put leaf and mulch and earth worms mixing in any top soil I have, once I have the mulch turn to dirt I then plant in it. The surrounding clay gives me a raised bed effect.
Shawna: Plant the trees in decorated 55 gallon drums and make benches to go around the drums. Then lasagna compost the ground and cover with mulch to let it cook. =) You can always plant the trees at a later time, but having them in the drums will give you your orchard.
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Just ask Kieran: Great advice. Really good comments. Makes this a really good site