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I am about to build my first elevated bed out of untreated cedar. My goal is to keep it as toxin-free and organic as possible. I need it to drain properly as well.

On the very bottom, on top of the cedar planks, I am going to use galvanized steel fencing wire, as a mesh. Is that going to leak anything into the soil?

More importantly, what should I use on top of the mesh? I've read about cardboard (not fully organic), newspapers (ew, ink) and landscaping fabric - all of which have drawbacks. I am starting to think I should just arrange a layer of 1-2" pebbles and dump the soil on top of it.

Can you provide advice on organic bottom for elevated garden beds?

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  • More details please, are there large trees close by with wandering roots? What is the soil type beneath where you are placing the beds? Clay, sand or ?? Why do you feel you have to do anything special for the bottom of the bed?
    – kevinskio
    Mar 19, 2022 at 12:06
  • The bed will be "elevated", i.e. on legs, so the soil beneath and the roots wouldn't matter. An elevated bed is one that the bottom of which is not touching the ground.
    – hyankov
    Mar 19, 2022 at 13:29
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    An organic option means that it will most likely rot over time, requiring you to remove the soil and replace it. A couple of examples are burlap and a 100% cotton material like muslin. Neither would hold the soil in by themselves, so you would definitely need some kind of grid under them. A system of cedar slats or a non-galvanized hardware cloth (1/4" / 2mm mesh) would be ideal if you don't like the idea of using a galvanized product.
    – Jurp
    Mar 19, 2022 at 13:40
  • I have no problem with galvanized hardware cloth, in fact, that's what I'm going to use. To clarify again, the bottom of my elevated bed would be untreated cedar boards, on top of which the hardware cloth, on top of which some sort of a non-toxic liner and then the soil. My question is about what that non-toxic liner could be.
    – hyankov
    Mar 19, 2022 at 18:12

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Given that the bottom of the elevated bed would be untreated cedar boards with hardware cloth on top of them, you could use burlap or even a loosely woven 100% cotton fabric such as muslin. Note that these options will rot over time, so you'll have to you to remove the soil and replace it when that happens.

An inorganic option that would work well for your installation is polypropylene silt fencing, which will hold all of the soil in place while letting all of the water drain through. It also lasts for, quite literally, decades, so there is no need to remove and replace the soil every few years.

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  • Using organic materials is only a secondary to building a non-toxic garden. If polypropylene silt fencing is non-toxic to use in gardening, I could do that.
    – hyankov
    Mar 20, 2022 at 14:40

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