Ask a Question forum: soil for a raised bed vegetable garden ?

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Name: Terry Koontz
Rio Rancho, NM
Jun 15, 2016 4:14 PM CST
i'm building a raised bed vegetable garden and don't know what soil to put in it.
Name: Bob
Vernon N.J. (Zone 6a)
Charter ATP Member Plant Database Moderator I was one of the first 300 contributors to the plant database! Forum moderator Heucheras Echinacea
Hellebores The WITWIT Badge Dog Lover Lover of wildlife (Black bear badge) Region: New Jersey Celebrating Gardening: 2015
Jun 15, 2016 7:29 PM CST
If you are not going to mix your own this worked pretty well for me.
Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest Photo Contest Winner: 2014 Vegetable Grower
Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database. Charter ATP Member
Jun 15, 2016 8:34 PM CST
Hi Terry!

I think it comes down to "what's available locally" and "are you rich?"
But when in doubt about what soil needs, add lots and lots of compost. Especially for vegetables which tend to be heavier feeders than many flowers. (Compost adds many things, like water retention AND better drainage, C for soil organisms, and a LITTLE N, P and K for plants.)

If you can scrounge up the makings for compost, make huge amounts of compost. Put a compost heap right in each of your beds, and grow in them while you research what soil would be best. (Look up "lasagna gardening" if you think, like I used to, that "you can't grow directly in 100% compost!" Also, throw some sickly and lagging plants onto a compost heap, some day. If their roots can reach the compost, they will often recover miraculously and take over the heap. )

Whatever soil you have, that plus an equal volume of compost will probably give you pretty good soil.

However you get there, fertile soil needs "some of everything".

Some fine stuff for water retention.
Some coarse stuff for drainage and aeration and "soil structure")
Some (lots) of organic matter to feed the soil organisms you need to have healthy plants.
Some water. (But not too much or your roots will rot. The bed needs drainage, but sandy soil has excessive drainage.)
Some air! (This is crucial. Roots need to breath. Too much water or too many fines = no air = roots drown = dead plant.)

Some soluble minerals. (If you have only sand now, you might need to add measured amounts of chemical fertilizer for a few years, until all the compost you add makes the soil fertile in its own right. But not too much fertilizer! A little too much fertilizer is actually toxic, especially high-N fertilizers. Fertilize weakly, weekly, until your "dirt" has become "soil".

If money is no problem, look up "dirt yards" or "soil" or "mulch" or compost". $20-$30 per cubic yard, maybe, plus $$$ to truck it to your home and dump it. If you have your own truck, that becomes more affordable.

I go for something like "three-way-mix": "topsoil", "compost" and bark or grit. But you are at their mercy when it comes to quality unless you can push your hands into their piles - and hope they take from the part of the pile that customers can see. I bought three cubic yards of soil once. First I checked carefully that the "topsoil" was light and loose and freely-draining. What they brought to my house was typical heavy clay. Thumbs down Even so, it was better than my VERY heavy clay!

I live where there is only clay soil, clay, and heavy clay. So if I pay for "store-bought" soil, I want something that improves drainage and adds organic matter: compost, medium/coarse ground bark, compost, grit, compost, very coarse sand and more compost.

If you have sandy soil yourself, you need to add organic matter and stuff that holds water: compost, I-don't-know-, and more compost. Fine bark holds water and lasts MUCH longer than peat.

But compost is consumed by the soil organisms you are encouraging. You have to add more every year. It would be nice to add 1-2 inches twice a year! But any helps. You can also "top-dress" or mulch your soil with the makings for compost, then call them "mulch". After they decompose and melt into the soil, you were "sheet composting" the whole time.

Some people mulch with a SIX INCH layer of leaves every fall. Depending on the type of leaves, it turns to compiost in 6-18 months (maybe 24 months for oak leaves).

Does anyone actually SELL clay? If so, add no more than 10% clay to your base sand, and see what that does. Go easy, because some say that any soil that has more than 20% clay, acts just like clay. My "soil triangle" would put that number around 35% ... but I would have to move to find out for myself.

When in doubt, just add a LOT of compost to your existing soil and make sure there is some drainage out of the bed. (Don't have plastic walls and plastic floor: that's a bathtub and roots won;t grow in a mud wallow.)

Cultivate that for a few years and give soil organisms and plant roots and ongoing compost additions a chance to improve your soil.

THEN consider spending $$$ on specific soil amendments when you know what you need, and what is just "dirt yard hype".

Oh, yes. Biosolids. The Cadillac of compost.

Depending on how much you believe local governments (hah!) or the engineers who run sewage treatment plants, "bio-solids" are just composted human manure, and as valuable as composted farm-animal manure. The engineers rave about all the tests they do, and HAVE TO pass - salinity, E. coli and other organisms, heavy metals, runoff chemicals - Class A biosolids are healthy like certified-pure rose petals if you believe the engineers.

In the past, there have been unregulated biosolids that were as saline as some farm manure, or had detectable heavy metals. Maybe Class B had detectable bacteria, but there are laws about where you can spread Class B (farms, I think, just not on lettuce and sell it shortly thereafter). Some people are still afraid of the problems that existed in the past.

If it were only the politicians telling me "we test for that!", I would not believe them for one millisecond. But the engineers say the same thing, and I trust them. I talked to a local "Schiessmeister" and he was really proud of his biosolids! But they give them away to Cedar Grove, who mix them with tons of sawdust and sell the result for a lot of money.

If you have a truck and a local sewage treatment plant, you can have the biggest compost heap in the valley for free ... but they do NOT test it to be odorless!

Everyone has a local sewage treatment plant, because everyone defecates. Kind of like North Carolina: where do transgender people go to the bathroom? The same places they've been going for generations. They haven't been "holding it in" all their lives!

Since biosolids are always going to be produced locally, and then spread on farms or given away to Cedar Grove (who charges for them), we might as well eliminate the middleman (so to speak) and use them directly.

Opinions vary, and those who suspect biosolids for various reasons may be righter than I am.
But if I had a truck, my neighbors would be complaining about the smell!

Name: Tom Cagle
SE-OH (Zone 6a)
Old, fat, and gardening in OH
Jun 16, 2016 12:05 AM CST
If my new bed is getting edging, I lay out a light blocking layer of cardboard, with edging laid in top of that. I fill up my bed with yard waste. And what ever finished compost I have. If i want a pretty esthetic, the top layer will be grass clippings.

I am not rich. I will steal from the curb my neighbors yard waste. Life goes on...

Jun 16, 2016 7:21 AM CST
Always look for compost with the OMRI label - then you know it is sewer sludge free. Growing Food in Human and Industrial Waste must stop! More scientists join outcry against land-applied sewer sludge (aka biosolids) See - and

Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest Photo Contest Winner: 2014 Vegetable Grower
Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database. Charter ATP Member
Jun 16, 2016 12:10 PM CST
Hi vindon, and welcome to NGA!

I read those, or scanned them, and did not see any suggestion about what SHOULD be done with composted human waste. If those authors oppose spreading it on land, are they suggesting dumping into rivers or the ocean? They do have to go somewhere.

I was more concerned that they kept repeating that "some scientists have concerns", but never mentioned whether 95%, 90% or 80% of scientists were confident that they were safe. There was some rhetoric that sounded (to me) distrustful of contrary evidence, and I started scanning faster each time I noticed that.

They kept repeating that there is lead in soil, and suggesting that some of that came from biosolids, but I did not see them acknowledge that there was some lead in biosolids before it was regulated, but now it is regulated and tested for. Now, the following is only my conclusion, but I thought to myself: "If they are trying to make people distrust biosolids by hiding the difference between the 1950s and the 2010s, should I respect their objectivity?"

Did they mention how many megatons of lead went into the air and soil and water from "leaded gas"? I didn't notice that, and yet complaining about lead in soil without mentioning the huge, well-known source, is actively misleading in my opinion.

They never said that XYZ level of lead was present in N% of biosolids tested. Not even from their own labs. That lack convinced me that I was not getting balanced information from them - that their goal was to push an opinion onto people, not to give them balanced facts so they could reach their own conclusion. That absence turned me off like a light switch.

Those authors might have had some information (not emotional rhetoric) that would have increased my concerns about biosolid safety, but I didn't notice any balanced information or any documented information present.

To my ears, the articles seemed to be pushing an agenda, not presenting facts in a balanced way.

(BTW - these guys were paragons of virtue compared to "popular 'science' writers" about GMOs, climate change, and many other "hot topics". I've been bashing them pretty hard because I thought they were presenting their article as "science" when it was rhetoric or propaganda (persuasion).

If their answer was "No, we ARE advancing an agenda, DUHH!" I would have to say "Good job, guys, you're better than most and not totally misleading."

I didn't notice any overt lies, but I thought I heard a very strong slant in almost every paragraph. That's their privilege, but if their goal is to persuade, not educate, I'll keep looking for facts from unbiased sources. The only facts that I took away from those articles with confidence were that the authors had a very strongly held opinion and not too many scruples about how they were willing to present their case.

They might be right or wrong. (But they use mostly emotion to persuade.)

The large majority of scientists who think biosolids are "safe when used as directed" might be right or wrong. (But they quote lab results.)

I become extremely skeptical when reading anything on any side of any debate, when the authors reveal that they will say and not say whatever advances their position, instead of presenting facts fairly and in a balanced way. Of course, that means it is very hard to find "good information" about anything that people are passionate about!

I apologize if this seems directed at you. It's directed at the authors, and who am I to complain that someone wants to advance an agenda instead of writing a scientific paper?

Name: J.R. Baca
Pueblo West Co. ( High Dessert (Zone 6a)
Aug 28, 2016 7:42 PM CST
I wont place my opinion here, the one my Co-workers have heard many a time, but I will say that RickCorey has pretty much hit the nail on the head. If you honestly FEEL that something is bad or unhealthy, then by all means DON'T USE,PRACTICE, or otherwise PATRONIZE it. Leave it at that and call it good.

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