@tapla (mid-Michigan, USDA z5b-6a) This might be an interesting topic for you.

You cannot "make" your own topsoil. Topsoil, despite what may be sold under that label at your local landscape supply, is ONLY the top few inches of the surface of undisturbed soil. Nothing more. Unless you have several thousand years at your disposal, topsoil is NOT a manufactured product. Real topsoil that is sold is generally the stuff scraped off when a new area is opened up for development. Otherwise, what is being sold is just a manufactured soil mix......but not topsoil.

Are there no suppliers in your area that offer a standard landscape soil or planting mix? This is a dead common product in my area and I have never known it to be completely out of stock anywhere. It is often brought in in bulk to raise or augment planting areas and you see landscapers with trucks full of the stuff. It's hard to believe with all the construction and landscaping activity in CA you cannot find a similar product. It will work well for just about any gardening purpose and for just about any plant type.

@gardengal48 (PNW Z8/9) I understand about topsoil not being something you can make. But nearly every wholesaler in this area uses the word "topsoil" liberally. Lyngso Garden in Redwood City is one of the biggest and best garden material suppliers in the entire Bay Area. Look at the bottom of their soil page here. "Top Soil" is part of the name of two products, which in reality are just clay loam and sandy loam.

What would you like me to call this instead? Screened Soil? Okay, let's call it screened soil.

I think the point you are trying to make is that it would just be easier to find a "Planting Mix" that I like and order that wholesale by the cubic yard. Effectively these planting mixes are the same thing I am doing, so I just save the time to mix it all together myself.

One consideration here is that I will be removing cubic yards of clay loam soil in my back yard, in order to install a new patio. To just remove that existing clay loam from my yard will cost me almost $700. So finding a way to re-use it by mixing it together with sand and some organic soil amendment, then using that in a berm for a new planting area, will in reality be cheaper than dumping the old soil and just buying all the new soil.

It is insanely expensive here to get rid of garden soil. You have to rent an 8 cubic yard dumpster from the garbage company at around $700. I tried to hire a person to haul away 3 cubic yards recently and he charged me $200 for his time to drive his trailer and the dump charged me $200 for the disposal. In addition to that I was paying a worker $25/hour for two straight days to load the trailer. So I was down more than $700 anyway.

"So finding a way to re-use it by mixing it together with sand and some organic soil amendment, then using that in a berm for a new planting area"

That may not be a good idea.

@davidrt28 (zone 7) Why?

Just be warned: if your thinking is that mixing sand into a clay based soil will improve its drainage, it can backfire.

Perhaps consider a hügelkultur berm if you have wood resource available.

@davidrt28 (zone 7) I have created sandy loam soils many times. I test the soil mix before I rely on it. In a raised bed or berm, you inherit the perched water table of the earth itself. It is not a container environment. So ingredients like clay, silt, and sand are not to be feared as they would in a container environment. If you have a specific concern, you should articulate that.

The mistake I have seen many people make is to not put enough sand into the soil mix, when their goal was to create a sandy loam. If you look at the soil triangle diagram, having more than about 20% clay in your final soil mix creates more of a clay loam than a sandy loam. People "amend" clay loam soils with 20% sand to 40% sand and they think they have a sandy loam, but that is not a sandy loam. The soil triangle says it is not sandy loam until you get close to 60% sand in the soil mix. I can feel that with my hands as well, having created many mixes, watered them and let them harden. I test the hardened soil with my hands to see how friable it is.

@gardengal48 (PNW Z8/9) I don't have a problem with my soil. I am trying to get feedback from other gardeners about soil mixes. And the reason I post more on this topic than other gardeners is because I have more ambition to understand the underlying science and variation of soil than 95% of other gardeners do. I get punished for that scientific curiosity over and over and over again.

The hardening of clay loam soil to a cement-like consistency after adding sand is all about selecting the wrong proportions of clay and sand. You need to observe the principles in the soil triangle. Sand should be 50% to 70% of the mix. Clay should be not more than 20% of the mix. When I do what the soil triangle tells me to do, it seems to work. Funny that.

It also matters what type of sand you use. A gritty sand makes it easier to develop a friable sandy loam.

As you develop your formula for the soil mix, test it! Flood it with water and let it completely dry out and harden. Is it cement? Can you poke a finger into it deep? Can you make it crumble easily? You can find the right soil mix and test that it has the textural qualities that you like.

Finally, does anyone look at the soil in my hands in the original post and think "cement"? Really? It doesn't behave like cement when hardened after compacting with water and drying.

Regarding the OSU website: I am NOT amending my existing soil. I am building a berm *above* the existing soil. The formula in my soil mix more or less mirrors the contents of "planting soil mix" sold by wholesalers.

I am not developing a container soil, and your advice that raised beds are not containers is agreeing with me, not making a counter argument.

"I am NOT amending my existing soil."

Oh, but you are!! You are taking the clay soil that was removed and that you do not want to pay to have hauled away and are trying to convert it into something it is not.

And as I cautioned earlier you are mistakenly using the soil texture triangle to create something. That is NOT what it is intended for......it is not a recipe for a good soil but only a means of evaluating what already exists. Ergo, you are most certainly trying to replicate a container soil with inputs like builders sand or turface.

I am not going to continue to argue these points with you. It makes my head want to explode. You have repeatedly reported troubles with your soils for growing whatever in something that does not suit them, which you then try to alter to no beneficial effect. That's why nearly every post you make prompts constant disagreements from others.

My suggestion to properly exercise your scientific mind is to go back to college and take some official courses in soil science. Then perhaps you will understand what we are attempting to tell you that somehow manages to fly over your head.

@gardengal48 (PNW Z8/9) I don't have a "problem with my soil". I am not reporting a problem. I am trying to learn about soil science well enough to make what wholesalers sell as "planting mix" on my own. So far your advice is about as science-based as "don't play with Mother Nature".

Your advice to just buy a wholesale planting mix and not hassle with these details is good advice. The rest of my question I think you just don't understand my intent, and in any case it is becoming clear that these kinds of questions need to be asked to soil science professors, not fellow gardeners.

" So far your advice is about as science-based as "don't play with Mother Nature".

There's plenty of science behind it.....look it up!! You will find countless references to the same thing.

btw, I have taught numerous classes in soil science for homeowners. I am not a complete dunderhead and DO know what I am talking about. You are just unwilling - or unable - to absorb it.

@gardengal48 (PNW Z8/9) You are far from a dunderhead, and I learn quite a lot from you.

These kinds of soil science questions are best not asked on gardening forums.

Sure soil science questions are good to ask in gardening forums. But yet again that whole putting down 95% of the members here pretty much sucks. SMH :(

@beesneeds I guess I missed the part of this thread where 95% of the members encouraged an exploration of soil science.

There are only three people in the thread besides you westes. All three of us had commentary about it. You chose to put down most of the whole site, again. Since you claim to be the better, maybe just do what you want. If you want to mix sand into clay, do it. If you want to use organic materials or synthetic, do it. Go forth with the confidance that you are always in the top 5% of everything gardening and do what you will with your yard. I hope your peppers grow well.

@beesneeds I have dozens of posts like these. The only person on this site who takes such questions seriously is Tapla. In years of doing posts on soil mixes, every response simply repeats attacks, and no one ever looks at the question as a science question.

I never claimed to be better. I claimed to have a serious question, which I do. You aren't reading 95% correctly. I am not in the top 5%. I am saying 95% have no *INTEREST* in these types of questions. Therefore I am wasting my time here to post them.

I am tired of you playing the victim card. You are not the victim. I am not attacking you. I am not putting you down.

westes, you should return to posting here. Your approach may seem unnecesarily nit-pickey to some of us---sometimes---but this forum is the best fit for you and it's certainly interesting to hear about your experiments.