# Charcoal in mixes



## keithrs (May 29, 2013)

I was wondering how important it is to add charcoal to potting mixes. I had read that plant can use it as a carbon building base since we don't grow them in leaf litter or there natural media per say.


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## NYEric (May 29, 2013)

I put it in mixes because it has filtering qualities, IMHO.


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## Ray (May 29, 2013)

In the 40+ years I've been growing, I have heard a lot of comments about charcoal "sweetening" the mix - helping purify it by trapping wastes. However, in order to be an efficient "trap" for such chemical species, the charcoal would have to be "activated", which greatly enhances the number of adsorption sites.

I suspect that the mere heat conversion from wood to charcoal does "activate" it to some degree - primarily at the surface I imagine - but its probably orders-of-magnitude less than that seen on truly activated carbon, drastically limiting its trapping capacity, and likely rendering it no more effective than other media components at absorbing stuff.

Having said that, I will add that all solid potting media components still absorb and trap minerals and wastes, which is why we need to repot regularly, even if the medium has not significantly decomposed, and I doubt that the charcoal does much to extend the time a mix stays viable.


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## Trithor (May 29, 2013)

I used to use zeolite in my potting mix for the same reason that people use charcoal, but stopped when it was pointed out to me that it has a high adsorption of nitrogenous compounds. It is used extensively in the farming of fish to reduce nitrogen in the water, obviously not ideal if you are trying to feed your plants!


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## keithrs (May 29, 2013)

I'm talking more about Terra Preta. Not so much to "soak up" bad things in the mix.


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## Ozpaph (May 29, 2013)

I use it because it used to be a lot cheaper than bark and was a good inert filler which doesn't breakdown. And because it was 'tradition'.


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## tomkalina (May 29, 2013)

We use it because roots seem to attach to it readily.....plus it keeps the mix from compacting. Plus we've used it in our mixes for at least 109 years:wink:


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## Paphman910 (May 29, 2013)

In my opionion, I think charcoal is a good additive as it keeps the medium from getting compacted and overly wet. To me it is just a substrate for the roots to attach to especially the epiphytic orchids.


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## Stone (May 29, 2013)

Trithor said:


> I used to use zeolite in my potting mix for the same reason that people use charcoal, but stopped when it was pointed out to me that it has a high adsorption of nitrogenous compounds. It is used extensively in the farming of fish to reduce nitrogen in the water, obviously not ideal if you are trying to feed your plants!



Zeolite has a very high CEC. As an example, peat has a CEC of between 50 and 200 m.e./L where's zeolite 1000 to 1500 m.e./L. It is sometimes used in the bedding plant industry to completely eliminate ammonium toxicity. The fact that we use rather larger and course materials in our mixes with rather low CEC ( around 100 m.e./L on average ) compared with the natural substrates like clay, humus and leaf mold/moss where paphs grow, I think including a small amount of course zeolite in a mix could do nothing but good. Obvously its not essential to have a high CEC when you are feeding regularly but it helps to ''even out'' the highs and lows of periodic feeding. Yes it would capture NH04, Ca, Mg and K but the plants will have access to them when they need it. Without a high CEC you need a constant trickle of nutrients for best results. 
I wish I could find a course zeolite but I can only get hold of 1-2mm particles.
I use charcoal for the same reasons as the others. It seems to be more a tradition than anything else but the mix just looks better with it.


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## Eric Muehlbauer (May 29, 2013)

Cec?


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## gonewild (May 29, 2013)

Eric Muehlbauer said:


> Cec?



Cation Exchange Capacity


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## Stone (May 29, 2013)

CEC = Cation exchange capacity. So cations like Ca, Mg, Al, K, Na, H+ being positively charged are attracted to negatively charged sufaces where they are held loosely. The CEC of a particular material is limited by the number of negative charges on the its surface. So if you apply Ca or NH04 it will exchange places with Mg or K or whatever. A plants roots can release H+ ions which can exchage places with ammonium for example and then be uptaken by the plant. I'm no chemist but I think thats how it works.
I have no idea of the CEC of charcoal.


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## gonewild (May 29, 2013)

Charcoal is good
Charcoal is good.

Have no idea why charcoal is good.

But charcoal is good to add to your mix.

Just make sure you use genuine hardwood charcoal made from Tropical Rainforests. (It really is the best) :drool:

Using charcoal in your potting mix prevents the charcoal from being burned and thus you are saving the planet.

Seriously over the years I notice a difference in the long term health of potting media that has charcoal added. Probably because the charcoal does not decompose as fast as other organic media so it helps maintain the physical condition of the media. I doubt it has any real benefit as far as absorbing toxins that help the plants.


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## The Orchid Boy (May 29, 2013)

I love using it from drainage and airation purposes instead of perlite. I hate how perlite sticks to my wet hands.


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## Stone (May 29, 2013)

gonewild said:


> > Charcoal is good
> > Charcoal is good.
> >
> > Have no idea why charcoal is good.
> ...


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## Migrant13 (May 29, 2013)

Ray said:


> In the 40+ years I've been growing, I have heard a lot of comments about charcoal "sweetening" the mix - helping purify it by trapping wastes. However, in order to be an efficient "trap" for such chemical species, the charcoal would have to be "activated", which greatly enhances the number of adsorption sites.
> 
> I suspect that the mere heat conversion from wood to charcoal does "activate" it to some degree - primarily at the surface I imagine - but its probably orders-of-magnitude less than that seen on truly activated carbon, drastically limiting its trapping capacity, and likely rendering it no more effective than other media components at absorbing stuff.
> 
> Having said that, I will add that all solid potting media components still absorb and trap minerals and wastes, which is why we need to repot regularly, even if the medium has not significantly decomposed, and I doubt that the charcoal does much to extend the time a mix stays viable.



To your point I wonder if the activated charcoal you can buy for aquarium use might be worth a try for sweetening purposes? It might be too fine a grade, too expensive and it may just absorb too much nitrogen (fish waste is nitrite I believe). Any thoughts on that?


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## gonewild (May 29, 2013)

Stone said:


> gonewild said:
> 
> 
> > Been strumming your guitar lately Lance?:rollhappy:
> ...


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## gonewild (May 29, 2013)

Migrant13 said:


> To your point I wonder if the activated charcoal you can buy for aquarium use might be worth a try for sweetening purposes? It might be too fine a grade, too expensive and it may just absorb too much nitrogen (fish waste is nitrite I believe). Any thoughts on that?



I don't think the charcoal will absorb much in the way of nutrients. Basically it absorbs gases not so much dissolved solids.


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## ALToronto (May 30, 2013)

Lance, charcoal will not adhere to anything. Maybe that's another reason why it's used for orchids.

My only experience with activated charcoal was in Russia, as a hangover cure. It's very effective for that.


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## Trithor (May 30, 2013)

So judging by the comments, I should hunt down that bag of zeolite again. They were nice consistant 8-10mm pieces, a bit like a fine gravel. It did make the pots a bit heavier when I was using it. (5 parts bark, 1 part chopped shagnum, 1 part coarse perlite and 1 part zeolite) We also have ready access to hardwood charcoal coming out of Namibia, perhaps I should add that in as well, just dont know how to beak it up and grade it without making a hell of a mess.


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## gonewild (May 30, 2013)

Trithor said:


> So judging by the comments, I should hunt down that bag of zeolite again. They were nice consistant 8-10mm pieces, a bit like a fine gravel. It did make the pots a bit heavier when I was using it. (5 parts bark, 1 part chopped shagnum, 1 part coarse perlite and 1 part zeolite) We also have ready access to hardwood charcoal coming out of Namibia, perhaps I should add that in as well, just dont know how to beak it up and grade it without making a hell of a mess.



Zeolite's best thing is for softening water by grabbing and holding Calcium. Is that what you want to happen in your media? Are plant roots going to be able to access the Calcium the zeolite holds?

If there is a bulk dealer for the Namibian charcoal they will likely have a hell of a mess in their shop. Their floor sweepings are perfect. Here in Peru they sell these chips and scraps to the poorest people in small bags.
To crush bigger pieces I make a small pile between 2 sheets of plywood and then drive a car over it a few times, then sift it through a couple different screens. Makes a mess but it is not as bad as hitting each piece with a hammer!


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## NYEric (May 30, 2013)

gonewild said:


> I'm going to try again with some Peruvian species soon.



Yes, I'll take some Peruvian species, thanks! :crazy:

Yes, charcoal is good!


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## gonewild (May 30, 2013)

NYEric said:


> Yes, I'll take some Peruvian species, thanks! :crazy:



Come get them!


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## Trithor (May 31, 2013)

gonewild said:


> Zeolite's best thing is for softening water by grabbing and holding Calcium. Is that what you want to happen in your media? Are plant roots going to be able to access the Calcium the zeolite holds?
> 
> If there is a bulk dealer for the Namibian charcoal they will likely have a hell of a mess in their shop. Their floor sweepings are perfect. Here in Peru they sell these chips and scraps to the poorest people in small bags.
> To crush bigger pieces I make a small pile between 2 sheets of plywood and then drive a car over it a few times, then sift it through a couple different screens. Makes a mess but it is not as bad as hitting each piece with a hammer!



I don't actually have any intention with the zeolite, I bought it years ago from the same supplier as my perlite. I was looking for a 'new best' ingredient for my potting mix. I used it for a short while on a few paphs, but then got scared as I was worried that it would 'steal' too many nutrients from my plants.
As far as driving over a few bags of charcoal, .... I am game for anything that annoys the neighbors, and this sounds like a winner!


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## Stone (May 31, 2013)

gonewild said:


> > Are plant roots going to be able to access the Calcium the zeolite holds?
> 
> 
> 
> Yes........yes they are,..... they are,.... they really really are


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## Bjorn (May 31, 2013)

Never use charcoaloke:
here are a few peruvian species and hybrids growing in limestone gravel and a little sand. it is one year since I received them now.oke: Should be 3 years out of flask then....
Yesterday


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## gonewild (May 31, 2013)

Stone said:


> gonewild said:
> 
> 
> > Yes........yes they are,..... they are,.... they really really are
> ...


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## Trithor (May 31, 2013)

Sorry to divert this thread a bit, but do I or do I not use the zeolite? I gather that charcoal is a good thing, but what of the zeolite?


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## annab (May 31, 2013)

what kind of charcoal is good?
all kind or someone specific ? 
Have we need some attention when we use It or not?wash or process it with chemicals ?
Thanks in advance,Anna


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## Trithor (May 31, 2013)

annab said:


> what kind of charcoal is good?
> all kind or someone specific ?
> Have we need some attention when we use It or not?wash or process it with chemicals ?
> Thanks in advance,Anna



No Anna, no chemicals, apparently you just have to drive over it a few times to irritate the neighbors!( especially those who are downwind of your makeshift crushing setup)


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## Stone (May 31, 2013)

gonewild said:


> Stone said:
> 
> 
> > Do you have proof to back up this claim? Unless I see an official published paper authored by someone with at least 2 pHds I won't believe it.
> ...


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## NYEric (May 31, 2013)

gonewild said:


> Come get them!



Me no crossing into US borders w/ plants any more!!


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## gonewild (May 31, 2013)

NYEric said:


> Me no crossing into US borders w/ plants any more!!



That's why I moved.


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## gonewild (May 31, 2013)

Trithor said:


> Sorry to divert this thread a bit, but do I or do I not use the zeolite? I gather that charcoal is a good thing, but what of the zeolite?



If you have the zeolite use it. But don't spend extra money to get it.


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## gonewild (May 31, 2013)

annab said:


> what kind of charcoal is good?
> all kind or someone specific ?



Best if it made from hardwood species.
Do not use the processed briquettes that have fire starter chemicals.
You can collect the charcoal from a burned area but try to use hard charcoal as opposed to soft and crumbly.


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## gonewild (May 31, 2013)

Stone said:


> Remember we are talking _exchangeable_ cations.



Exchangeable? As in you want to return them? 



> http://www.zeolite.com.au/products/technicalspecs.pdf



This article is published by the company selling eolite so we can't believe what it says. oke:

I'm just joking. :wink:

Zeolites are very good soil amendments but I don't know how well ephyphytic orchid roots would benefit from the cec properties.


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## Ray (Jun 1, 2013)

gonewild said:


> Zeolites are very good soil amendments but I don't know how well ephyphytic orchid roots would benefit from the cec properties.


A very good point, Lance.

Orchids have evolved in an environment of very little cation exchange opportunity. When it rains, the ions are up for grabs for a very short time as they flow by, and then they're not. I was reading (more Benzing) about the "unique" ability of orchid-root velamen to instantly capture ionic species, unlike any other root structure. Makes sense to me.




Ray Barkalow
Sent using Tapatalk


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## lepetitmartien (Jun 1, 2013)

In case, the article on Biochar of the Wiki is full of references. I've flown other the french version, it's very documented and the english version is not far behind.

Complex stuff not completely explained yet. But to sum up: it's GOOD.


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