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Best ways to adjust PH in organic gardening?

I am trying to garden indoors as organically as possible. Most things I have read say that if you need to raise your PH (make more alkaline), that you add dolomitic or calcitic limestone, or oyster shells. And that if you need to lower the PH (make more acidic), you can add sulfur, peat moss or coffee grounds.

I have some questions about this...
1. Is "dolomitic limestone" organic? Or is it made out of chemicals?
2. Is "sulfur" organic? Sounds a little dangerous lol.
3. Coffee grounds... This one is based on hearsay. Will the coffee end up eventually molding inside the pots? I am a little concerned about this since I live in a high humidity area.

Any other ways to adjust PH without using chemicals?


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MC Mixin Bricks
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I make my soil acidic with any fallen pine needles, cones I collect. its better to grind them up before mixing with you soil.

as for going the other way, crushed(powder) eggshells. that should raise it. :wink:

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Green Thumb
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I don't consider myself to be an expert on this. So, someone with more knowledge can correct me if I am wrong. But, here's what (I think) I know.

Sulfur is a naturally occuring chemical element; it is an essential element for life.
Lime is pulverized Limestone or Chalk; both naturally occuring mineral "rocks".

In my opinion, neither Sulfur or Lime would be a "chemical" in the way that most gardeners use that term... as it seems to me that organic gardeners primarily seek to avoid man-made petro-chemical fertilizers and pesticides.
As far as I know, Sulfur and Lime are welcome additions to organic gardening [when needed, and when used and applied correctly].

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Super Green Thumb
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To me there is a distinction between "natural" or naturally occurring and organic. Organic literally means carbon based, derived from life. In my organic garden, besides not using synthetic and petroleum based chemicals or any poisons, I try to focus on local, sustainable, derived from life additives if any. Eventually I am aiming for a complete food web where nothing comes from outside my property (on my little city lot, I am not there yet! :) )

So while sulfur and lime are naturally occurring, they are not necessarily organic, depending on definition.

The coffee grounds should not mold if mixed into your potting soil.

cottonseed meal is an acidifier, as is peat moss (but not sustainable, though, it is a mined product). For gardening indoors in containers, you can just put a little lemon in the water.

Be sure you know whether you need to add anything... not adding anything is simplest and is often fine!

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Sulphur is mined near active volcanoes, as it's a byproduct of volcanoes. Sulphur is commonly used in medicines as a filler for pills. May not be "organic" but fits in the completely all natural ideals of rganic growing(man doesn't make it, nature does).

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rainbowgardener wrote: Organic literally means carbon based, derived from life.
only in chemistry. In real life it basically means the whole is more than the sum of its parts. If my performance is called organic, it's not carbon based music. Though you could flatter me by saying it is derived from life. When european monks first started singing together, that was called organum. It's the togetherness that counts.

Likewise, in the art of gardening, the word organic has nothing to do with carbon. It's about things working together, not specific inputs. Which is good, because many nasty chemicals are organic compounds.

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Alan in Vermont
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laura murphy wrote:Well I think that both sulfur and limestone can be either organic or unnatural, just depends on where it's coming from.
I'm trying to figure out how an element (Sulphur, #16 on the periodic table, S) or a rock (all types of limestone) can be anything BUT natural. For the most part both of those things come out of a hole in the ground. Sulphur may be a byproduct of some chemical processes but it is still elemental. As fas as limestone I have never heard of any source for that other than a quarrying or mining operation.

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Just a note... I put some sulfur into the soil of one of my more acid-loving plants (indoors), and it created a rather funky smell that made my nose twitch every time I walked past it. I think probably sulfur is not good to be used indoors

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Isn't wood ash fairly alkaline?

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