Ask a Question forum: What Soil do I Use for My Raised Beds?

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SedgeyGrass
Apr 29, 2017 6:30 PM CST
So I'm planning to build some raised beds because the only space I have left for gardening is crushed rock covering a thin layer of clay soil before it turns into caliche (heavily compacted clay that has quiet literally turned into stone and I am NOT willing to spend the time and effort to jack hammer it out). I have a couple of questions. 1.) How high should I build the beds since I can't dig down? I was thinking 1 and 1/2 feet or should I do more? 2.) Is it ok if I place the raised beds directly on top of the gravel? I figured it would give it good drainage anyway. 3.) What should I use for soil? All the bagged soils I find say to mix it 50/50 with your own soil but I have no soil to mix it with. I thought about making a peat moss mix but then again I've only ever seen that used for potted flowers and I don't know if that'd work for veggies. Answers are highly appreciated!
Name: Carol
Santa Ana, ca
Sunset zone 22, USDA zone 10 A.
Charter ATP Member Hummingbirder Lover of wildlife (Black bear badge) Orchids Region: California Plant Identifier
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ctcarol
Apr 29, 2017 6:46 PM CST
I'm sure you will get more opinions, but if it were me, I would go 2' and either use potting soil or get a load od top soil from a reputable source, and mix in compost. Depends on what you want to grow in it.
Name: Yardenman
Maryland (Zone 7a)
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Yardenman
Apr 30, 2017 2:08 AM CST
I can help on this. It may not be easy.

First, you want one of those 16"+ long augers that fit into an electric drill. They can cut through hard soil. It takes some effort, but it is worth it.

When your soil is bad, you have to build high. I have hard clay soil, so I built framed beds a foot high. When they were in place and anchored, I drilled down another foot to loosen the clay soil. I loosened it more with a leverage fork. I tossed most of it out behind a low spot behind a shed.

So I had 2' depth. I added some woods soil for the bottom foot, and then filled the beds with a mix of 1/4 peat moss, 1/4 sand, and 1/2 50/50 bulk topsoil and compost from a local nursery. Mixed it thoroughly with a garden fork.

After it settled with watering, I topped it to an inch below the frame tops.

My seedlings are thrilled. My direct-seeds grow. After 2 years, there are worms everywhere!
Name: Yardenman
Maryland (Zone 7a)
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Yardenman
Apr 30, 2017 3:43 AM CST
Meanwhile, I have a question. I have a weedy invasive viney plant that a neighbor put in his back yard. He has since moved. I can't find it for certain any place I search.

It spreads fast. The vine seems to max out 2'. More a groundcover than a vine really. It has a generally heart-shaped leaf. It does not climb. It is evergreen. The flower is about 3/4" and bright blue.
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Can anyone tell me what this horrible spreader vine is and how to kill it?

I even turned a trash barrel over some of it last Fall and it grows cream-white 6 months later (and not dead yet).


smokingdonkey
Apr 30, 2017 12:20 PM CST
Use glyophate chemicle or any contact weed killer, (ask at your local garden supply store for contact weed killer)
Contact weed killers are sprayed or brushed on (use protection for face if spraying and rubber gloves if hand painting these contact chemicles on,
Contact chemicles are soaked onto the leaves and this chemicle is taken into the plants roots via the leaves
a week or so and the leaves start to turn yellow, do not remove these let the chemicle do its work until the leaves are dead and very dry.
"I myself use the 2 coat method ie spray a second coat 3 days after the first, (never fails to work)

TIP only spray when the weather is very calm, its a good idea to cover any plants you dont want to kill as contact weed killer will kill everything it comes into contact with,

TIP 2. If you find the leaves on the plant your trying to kill are of the kind that repels water such as rubber plants etc Then before you spray the plant to want to kill give it a pre spray with washing_up Liquid,

This has an oily effect on the leaves and the contact chemicle will stick to the plant easier.5

smokingdonkey
Apr 30, 2017 1:11 PM CST
SedgeyGrass said:So I'm planning to build some raised beds because the only space I have left for gardening is crushed rock covering a thin layer of clay soil before it turns into caliche (heavily compacted clay that has quiet literally turned into stone and I am NOT willing to spend the time and effort to jack hammer it out). I have a couple of questions. 1.) How high should I build the beds since I can't dig down? I was thinking 1 and 1/2 feet or should I do more? 2.) Is it ok if I place the raised beds directly on top of the gravel? I figured it would give it good drainage anyway. 3.) What should I use for soil? All the bagged soils I find say to mix it 50/50 with your own soil but I have no soil to mix it with. I thought about making a peat moss mix but then again I've only ever seen that used for potted flowers and I don't know if that'd work for veggies. Answers are highly appreciated!


Hi
the very first bit of 100% advice i'd give is to get your self a set of gardening books,
the reason i say this is because gardening really is a vast subject and anyone new to the hobby can be quickly put off because of bad results or no results after you've put the labour in never mind the cost.

Try getting your books from charity events (stores etc) the reason i say from these places is because you'll spend a lot less for books that we're 9 times out of 10 written years ago by very experienced garden writers
you had to be good to get into print years ago.

A lot of the modern books are very thin and ive even seen books the size of A4 paper showing one full page of a picture of a cabbage !!!!!!!!! and the front cover and back cover had large full page size pictures of the writer,
The type of older books you'll find in thes rescue / cancer research shops etc have been purchased by gardeners who for one reason or an other no longer garden "Maybe they're no longer with us and are now looking after the borders in heaven "who knows"

But one thing we do know is these older books we're bought once by someone who had a vast interest in the subject "GARDENING" and wanted to know from the experts how and when to do things and what soils about.
Any soil/compost needs "HUMUS" Google this word and you'll understand why ive given you this advice and what you need for your raised beds, plus before you run learn to walk first,

raised bed or not, Lime lovers /Acid lovers these are soils that are as different as chalk and cheese and if you try growing an lime loving plant in an acid soil you'll never get any worth while results "the same can be said for sun or shade loving plants, So you need to know north or south in your garden.
Now as i said when i started this reply, before you start to try to grow Anything!!!!!

learn about soil,
It'll save a lot of wasted time and effort ref clay soil at the bottom of a dug out area, If you've a good layer of compost ie at least 4inch deep with plenty of rotting veg etc to feed the humus (worms) the clay will with time be broken down by the HUMUS,
without "HUMUS" the dug clay will return to being a clay hard pan effect that collects water and if you have a rainy season the plants root tend to rot. Again drainage in the bed is yet a further item you need to understand before you start planting,
Have a thought what ive said and remember a lot of these forums will give you a lot of replies from a lot of good meaning people but are they pros's in the gardening world or keen amateur's?

If you start off on the right road you'll enjoy your results for a life time (I have) but if you start off making every mistake going it'll kill your keen spirit and you'll end up thinking you have to have green fingers to be good at growing things Hilarious!
Anyone who has green fingers needs to see a doctor fast they've got signs of gang'rene.

Good luck and please take this advice its the best you'll get.

Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
Frugal Gardener Garden Procrastinator I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest
Photo Contest Winner: 2014 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.
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RickCorey
May 1, 2017 6:40 PM CST
Hi SedgeyGrass! Welcome to NGA.

I think that I would rake the gravel aside. Actually when fine soil sits on top of a layer of gravel, the capillary path is "broken" and the soil no longer drains well. They call that "perched water" and it is somewhat counter-intuitive.

Sitting right on the clay layer will make your raised bed drain slightly better, especially if you amend that clay layer a little as you build the bed. Compost is probably the best addition, but finer stuff like peat and bark will help d5ianage and aeration for a few years. If your plant roots have invaded the clay by then, the clay will eventually soften and become part of your root zone.

I've been told that caliche is "like rock", so I won't speculate. But over time, with organics leaching into it, and with roots and worms trying to tunnel into it, that clay will eventually become softer.

BUT there is one thing you can do to improve drainage. Look for really old gardening books, like from the 1940s and 1950s. They wrote for people willing to do the work.

If you GRADE the impervious parts of your soil (clay and caliche), you can make the water go wherever you want, as long as you have some "downhill grade" to work with. Your neighbor may object if you divert all rainfall into his or her yard, but that's a separate issue.

Mainly, you want any excess water in your raised to move first DOWN, until it hits the "floor" of your bed, which I guess will be clay or caliche. As long as the soil mix in your bed drains well, that water WILL flow down and let air follow behind it, which keeps your roots alive.

Next you want the water to flow OUT of your bed so your roots don't drown and die, then rot.

Water only flows DOWN, so the floor of your bed needs to slope towards the downhill edge or downhill corner. I do that after after I've removed my soil to amend it. The slope can be shallow or steep as long as it is continuously DOWN.

(The floor of the bed must slope gradually down if your subsoil is impervious and you want water to drain away. But the surface of the soil should be level so that rain and heavy watering do not run off or pool unevenly.

A pick will help to break out chunks. A hoe can "shave" hard clay. Clay is much soften when SLIGHTLY damp, but very sticky and heavy if too wet.

So the water has flowed DOWN to the floor of the bed.
The sloped floor made it flow to the downhill corner or edge.
Now you need it to go away so you don't collect a pond in your yard just below your raised bed.

You might need to cut a slit trench to give the water a path to get from your bed to the lowest spot in your yard (or the neighbor's yard). I usually cut the slit trench roughly using one blade of a mattock (it's narrower than my hoe). Then I wait for a hard rain. The water fills any low spot and is blocked by any high spot in the trench. I just walk to where the biggest puddle is accumulating and use the mattock to level that high spot. Now the whole puddle rushes downhill and levels off the rest of the trench for me.

P.S. I use concrete paving stones stood on edge as walls for raised beds (8" tall, 12" tall, or 16" tall. Water diffuses right through those! I found that beds were drying out much too fast at the corners, and somewhat too fast at the edges. Now, If I'm going to want a bed to stay pretty moist, I line the concrete pavers with plastic cut from bags of bark.

https://garden.org/thread/view...

Name: Yardenman
Maryland (Zone 7a)
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Yardenman
May 2, 2017 12:20 AM CST
smokingdonkey said:Use glyophate chemicle or any contact weed killer, (ask at your local garden supply store for contact weed killer)...


Thank you (and I mean that). I've tried spraying them with glyphosate but it only slows them down. I've weed-whacked them yesterday and will try spraying again on the new leaves; they may be more susceptible.

But I would really like to know what they are.

Name: Yardenman
Maryland (Zone 7a)
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Yardenman
May 2, 2017 12:48 AM CST
RickCorey said:Hi SedgeyGrass! Welcome to NGA.

I think that I would rake the gravel aside. Actually when fine soil sits on top of a layer of gravel, the capillary path is "broken" and the soil no longer drains well. They call that "perched water" and it is somewhat counter-intuitive.


I hate to criticize such a long and well-written post, but I think you are over-working things.

Any raised framed bed is going drain around the edges even if the edges are slightly below-ground. Sloping materials for drainage won't last as frost-heaving mixes the soil and worms also do the same.

I sheet-layered soil once and 2 years later used a post hole digger to make space for my tomatoes. The layers were gone. And there were small stones on the surface that were 12" deep to begin.

Yes, I wouldn't bother with gravel at the bottom of a framed bed. I did have some ground-level soil where I build a few framed beds, and used an 16" auger to poke hole through it. I got through a clay layer and hit sand, so that solved the drainage problem there.

Another way to solve framed bed drainage if you are building on seriously bad clay is to drill a few holes around the bottom and staple some screen or landscaping fabric on the inside edge.

If there is a gardenwide drainage problem due to low-laying area, you put you garden in the wrong place. ;) But that is solvable by adding soil or mulch between the beds until the soil is high enough for water to move away.

Yes, slit trenches are good too. But in my experience, they tend to fill with washed-in soil and become "just more ground".





Name: Lyn
Weaverville, California (Zone 8a)
Garden Ideas: Level 1 Garden Sages Celebrating Gardening: 2015
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RoseBlush1
May 2, 2017 2:15 AM CST
Yardenman said:

Thank you (and I mean that). I've tried spraying them with glyphosate but it only slows them down. I've weed-whacked them yesterday and will try spraying again on the new leaves; they may be more susceptible.

But I would really like to know what they are.



@Yardenman ... your vine is vinca, also known as periwinkle and creeping myrtle.

Here are a couple of links you might find interesting:

http://www.enature.com/expert/...

https://www.gardeningknowhow.c...

@SedgeyGrass ...

Welcome! to NGA

I totally agree with getting some gardening books, but they too can be somewhat overwhelming. Feel free to ask a lot of questions. Also, there are a lot of articles about raised beds and soils on the NGA site.

Click on the down arrow next to COMMUNITY at the top of the page
Click on COMMUNITY IDEAS
then in the SEARCH box to the far right at the top, type in something like "raised bed soils"

I haven't read all of the articles that came up, but some of them sound quite interesting.

I'd rather weed than dust ... the weeds stay gone longer.
Name: Yardenman
Maryland (Zone 7a)
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Yardenman
May 2, 2017 3:31 AM CST
RoseBlush1 said:

@Yardenman ... your vine is vinca, also known as periwinkle and creeping myrtle.

Here are a couple of links you might find interesting:

http://www.enature.com/expert/...

https://www.gardeningknowhow.c...


Thank you, thank you, thank you! Knowing the name helps. I am ordering some triclopyr from Amazon. I dislike using herbicides, but I am becoming desperate. I have lots of LARGE cardboard to use first as shields from spray drift and then to lay over to cover the vines. And lots of cinderblocks to hold the cardboard down in place.

Just knowing what this vine IS, is a weight off my mind.



Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
Frugal Gardener Garden Procrastinator I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest
Photo Contest Winner: 2014 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.
Image
RickCorey
May 2, 2017 12:10 PM CST
>> Sloping materials for drainage won't last as frost-heaving mixes the soil and worms also do the same.

I knew that worms would eventually soften the underlying clay, in effect making the floor of the bed "fuzzy", as if mixed with better-draining soil..

I never considering my hard clay being able to experience frost heaves! Since I have to moisten it carefully and still whack it with the sharp point of a pick to break it up, I think of it as "soft rock".

But I bet you're right about frost heaves. I know that clay (no matter how hard) expands as it moistens and shrinks as it dries. I guess freezing would cause it to expand and exert huge force - enough to push really-hard-clay out of the way.

>> If there is a gardenwide drainage problem due to low-laying area, you put you garden in the wrong place. ;)

That probably is the most important thing. If you want a deeper root zone, don't site your bed over a low spot in your yard!

Maybe my concern is only relevant during the first year or so, but I figured that it would be a bad thing if the impervious floor of a bed sloped "the wrong way" so that it trapped water and held it.

I'm going to dig up some of my beds and see what the "floor" is like after several winters of occasional frost heaves. We have pretty mild winters (Zone 8).
Name: Tom Cagle
SE-OH (Zone 6a)
Old, fat, and gardening in OH
Coppice
May 2, 2017 12:14 PM CST
In my own garden, I would fill a raised bed with leaf litter, bark mulch, or compost. Depending sole-ly on what was free. I would lay on a couple layer of cardboard first as a light block to eliminate previous plants--weeds. and then fill a bed built of a single teir 2X8's.

I would plant tomato or corn the first year, And not expect much from them.

Herbicides routinely take more than a single year to break down in raised beds, so I get to a productive garden faster, and for a whole lot less money,

Eventually after adding leaf litter you will have introduced enough earth worm egg cases and they will begin to till your beds for you, They will in time till up sterile media like gravel or sand, if you keep them well fed.

There is no, one-and-done in gardening. if you start with chemical interventions, you make yourself hostage to their result.
free for them in need:
http://need4seed.freeforums.ne...
Name: Lyn
Weaverville, California (Zone 8a)
Garden Ideas: Level 1 Garden Sages Celebrating Gardening: 2015
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RoseBlush1
May 2, 2017 12:27 PM CST
Yardenman said:

Thank you, thank you, thank you! Knowing the name helps. I am ordering some triclopyr from Amazon. I dislike using herbicides, but I am becoming desperate. I have lots of LARGE cardboard to use first as shields from spray drift and then to lay over to cover the vines. And lots of cinderblocks to hold the cardboard down in place.

Just knowing what this vine IS, is a weight off my mind.



Sorry it has been a problem for you. Vinca can be a wonderful erosion control plant.


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I'd rather weed than dust ... the weeds stay gone longer.
Name: J.R. Baca
Pueblo West Co. ( High Dessert (Zone 6a)
josebaca
May 3, 2017 12:14 PM CST
SedgeyGrass;
Get 'Lasagna Gardening' by Patricia Lanza. Once you grasp the basics of that concept, you could build beds on top of concrete and have NOOOO problems .I've always felt the natural way is usually the bestest, cheaperest and in the long run healthiest way to go.

Good luck!

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