Charcoal

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TheLorax

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I've repotted all of my phrags and am now working on repotting all my paphs. While poking around on the Internet for potting mix information, I ran across this-

http://www.rhs.org.uk/learning/publications/orchidreview/orchid0307/roots.pdf
If charcoal is included in the mix, be aware that it will absorb fertilizer salts and water impurities after a time and can inhibit root growth. I have observed healthy root tips encounter a piece of charcoal, stop growing, turn black and die. Not the entire root –just the tip. I don’t think that flushing the pot takes care of this problem completely with aged charcoal. When roots that are in contact with charcoal die, it may be an indication that the mix needs replacing.
I haven't noticed any healthy root tips that stopped growing or turned black and died when they encountered a piece of charcoal but I did notice this happening with larger pieces of pumice in mixes. I haven't been growing slippers long enough to be able to comment on whether charcoal noticeably inhibits growth over time but I was thinking flushing frequently would have take care of this. What thoughts are out there on charcoal and flushing or on what is quoted above in general.
 
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Corbin

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I have not been at this long enough to help here. I to would like to hear what the more experienced growers say.
 

Rick

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Charcoal can absorb some metals (trace nutrients), but does not absorb major salt ions. It's main purpose is to absorb organics, and "sweeten" the mix by keeping down organic acids. It is also very good at picking up (and neutralizing) the chlorine from tap water which could be beneficial.

In many cases it will get overgrown with various microbes (like any other porous object in the mix) that will utilize the absorbed materials in the charcoal matrix. Depending on the micro-ecology you end up with the transfer back and forth between plant roots and charcoal chips may or may not be beneficial.
 

TheLorax

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The absorption of some trace nutrients )Lithium, Boron, Chlorine, Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Germanium, Selenium, Molybdenum and Iodine- forgot which ones charcoal absorbs) is why it is so widely used in CP culture and I have read at least one paper on this.

It's the transfer back and forth rate that I don't quite understand however most probably moot if the plant is re-potted with any semblance of regularity.
 

Rick

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The absorption of some trace nutrients )Lithium, Boron, Chlorine, Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Germanium, Selenium, Molybdenum and Iodine- forgot which ones charcoal absorbs) is why it is so widely used in CP culture and I have read at least one paper on this.

It's the transfer back and forth rate that I don't quite understand however most probably moot if the plant is re-potted with any semblance of regularity.
Apparently the "absorption" of chlorine is actually a catalytic process and activated carbon has a theoretically infinite capacity to neutralize chlorine in water. Once it absorbs the other stuff it will hang onto it unless you cook it in nitric acid or use some other abusive solvent technique. But bacterial colonization can slowly move things back and forth between plants and the carbon substrate.
 

TheLorax

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Yes, they used to use charcoal a lot around here for the water because it used to be chlorinated. Not so any longer.

I still believe charcoal to be a great additive when one has to resort to using well water from time to time... provisional upon re-potting the plants into fresh medium when it begins looking spent.

Thanks for the explanation.
 
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Mrs. Paph

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I don't know that charcoal could be bad, unless everything else in your mix has gone 'sour', in which case the charcoal would be coated in crud too. Unpotting my Paphs, when there's charcoal in the mix, roots can often be found firmly wrapped around it with roots hairs everywhere, so I use it when I have it on hand - if I have some sort of expanded clay aggregate instead, I use that and see the same thing on repotting.
 
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Eric Muehlbauer

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I think you already stated the important idea yourself....charcoal is fine as an additive, (or at least harmless), and will not cause problems if plants are repotted on time. Take care, Eric
 

TheLorax

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I believe charcoal to actually be beneficial as an additive to people like me who have to resort to using their well water for their plants from time to time. But, I have noticed a decline in CPs when the medium isn't changed in a timely fashion and assumed there was something going on that dictated a change to fresh medium other than the decomposition of organic materials in a mix. Re-pot CPs in fresh medium and they take off again. Figured the same thing would hold true for orchids. My bet is that charcoal has a lifespan in a medium of anywhere around 1-2 years before it begins being a problem for a plant. For some reason I wasn't thinking along the lines of the charcoal getting "overgrown with various microbes". It's those microbes that will start decomposing in the medium that are going to create a big problem over time. They are colonizing. Re-potting in fresh medium is the best of both worlds.
 

paphioboy

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just my 2 cents worth... in the tropics, ALL epiphytic orchids are potted in charcoal (or broken brick n charcoal OR polystyrene n charcoal mixture).. so epiphytes can take it well, no blackened roots or anything.. it is also recommended to mix charcoal with soil to pot terrestrials... i use this on paphs, and so far so good... :)
 

myxodex

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As I understand it charcoal becomes saturated with organic compounds quite quickly as well as providing an excellent subtrate matrix for bacteria as mentioned above. I stopped using charcoal in potting mixes not because it is bad but because it's beneficial absorbtive properties probably won't last more than a few months in the medium. I do use aquarium grade activated charcoal as substrate in an aquarium filter in a glass tank that I use to store rain water before using it on my plants. The water is vigorously circulated by the filter and is thus kept well aerated and an aquarium heater keeps the water at 24C. In this set up I change the charcoal every 2-3 months as this is when the ability of the charcoal to extract a blue dye from the water decreases. Of course this might not be the same for different setups as it will probably depend on the organic content of the water.
Cheers,
Tim
 

TheLorax

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I disagree based on extremely limited personal experience with orchids. Perhaps charcoal only lasts a few months when used as you are using it however I haven't noticed carnivorous plant decline until around the 2-year mark and most of those are sitting in trays of water for extended periods of time while they are actively growing. I do have a few thousand carnivorous plants. I suspect the same may very well hold true for perhaps all but any plants grown hydroponically or semi-hydroponically wherein which they would be basically sitting in water. As far as the few paphs and phals I have had for several years, all of them have had fine or lump charcoal in their potting mixes and I haven't noticed any decline at all in them and I know for a fact I didn't re-pot some of them for well over 2 years. My original paphs and phals do not sit in water trays but I do have a few phrags that are sitting in water trays.

When my husband used to have fresh water aquariums, I did change his charcoal packs every few months. I got tired of taking care of his fish tanks so I converted them all to lowland Nep chambers. Oh happy day, no more filthy dirty charcoal packs to change out.
 

myxodex

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I disagree based on extremely limited personal experience with orchids. Perhaps charcoal only lasts a few months when used as you are using it however I haven't noticed carnivorous plant decline until around the 2-year mark and most of those are sitting in trays of water for extended periods of time while they are actively growing. I do have a few thousand carnivorous plants. I suspect the same may very well hold true for perhaps all but any plants grown hydroponically or semi-hydroponically wherein which they would be basically sitting in water. As far as the few paphs and phals I have had for several years, all of them have had fine or lump charcoal in their potting mixes and I haven't noticed any decline at all in them and I know for a fact I didn't re-pot some of them for well over 2 years. My original paphs and phals do not sit in water trays but I do have a few phrags that are sitting in water trays.

When my husband used to have fresh water aquariums, I did change his charcoal packs every few months. I got tired of taking care of his fish tanks so I converted them all to lowland Nep chambers. Oh happy day, no more filthy dirty charcoal packs to change out.
I never said that charcoal is harmful, or not useful in media in the short term, just that it is unlikely to be active for extended periods. That fact that your plants do not decline is not evidence that the charcoal is still active. It may be that the most important time for the presence of charcoal is in the first few months after repotting when the plants may benefit from a "sweet" start in their new mix. It is also possible that the coarser/chunkier grades of charcoal last longer. My point is essentially that I believe that for my paphs I'd rather treat my water with charcoal and use the space that would otherwise be occupied by the charcoal for other medium components such as dynarock which I'm confident is beneficial. Another reason for treating my water is that I grow mounted angraecoid orchids which can then also benefit.
Cheers,
Tim
 

Roy

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My findings with using Charcoal. Charcoal is fine in a potting mix but only for a short period of time. I have found that when a regular fertilising program is followed, charcoal seems to become toxic to many orchid plant roots within 12 months. This can be easily seen by any new roots that comes in contact with charcoal blacken rapidly and stops growing. While the char' is fresh it ok. The way the charcoal is produced AND the type of timber is made from could be the key to its success or failure. This where growers world wide say they have good or bad results with it. Personally, I don't use it any more because I find its of no great benefit and its too hard to get good quality product.
 

TheLorax

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Hey myxodex,
That fact that your plants do not decline is not evidence that the charcoal is still active.
You have a very valid point here. One of the reasons why I started this thread was to try to sort out what’s going on, on not going on, with the charcoal. I am wondering if plants that sit potted in a charcoal mix that are grown hydroponically and semi hydroponically aren’t deriving even less benefits from charcoal because the charcoal in their mixes is getting overgrown with assorted aquatic microbes in addition to getting overgrown with all the various microbes mentioned by Rick earlier. A double whammy so to speak for plants grown hydroponically or semi-hydroponically.

Another reason for treating my water is that I grow mounted angraecoid orchids which can then also benefit.
I don’t grow those types of orchids, I only grow the most basic that seem to like what I have to offer them leaving the difficult ones to the heavy hitters like you but have you ever considered RO/DI water for your plants? I have RO/DI equipment here and really love it wishing only that I had better water pressure and could use it more frequently. I currently have by-passed the DI phase (water pressure issues) and really try to use it whenever possible. Next bet for me is rain water however I’ve found I have to fiddle too much with rainwater by leaving my rain barrels disconnected then running out in the rain to reconnect my rain barrels to the gutters after it’s rained for a while. Leave them connected all the time and my rain water tests out way too high. When it first begins to rain around here, I am convinced pollutants come down with it. Let it rain good for even so much as 15 minutes then go out and re-connect the gutters and that rain water tests out well under 50 ppm.

Hey Roy, thank you very much for these comments-
I have found that when a regular fertilising program is followed, charcoal seems to become toxic to many orchid plant roots within 12 months.
I had never fertilized the few orchids I have up until most recently when MSU was recommended. I have just begun to fertilize my orchids. Carnivorous Plants have never and will never be fertilized by me unless something earth shattering hits the scene in CP culture.
 
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Mrs. Paph

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I use a little bit of rain water, from an icecream bucket since that's all there's room for really at my apartment, and it tests really nice. I avoid any water that's touched anything on the way down though - for example, I don't collect from gutters, in case of toxins, though I admit I haven't look into what might be on shingles that would be bad for orchids - I just don't have that many things I can test for on my fish water quality strips and wouldn't know anything was wrong if the pH/nitrates/nitrites didn't come up funny.
 

TheLorax

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This will work as well as any to test for total dissolved solids in the water you use for your plants-
http://www.watervalue.com/testkit/tds.html

To the best of my knowledge, it's perfectly fine to collect from gutters. Just don't do it until it's been raining about 15 minutes or so. The particles from asphalt shingle roofs do come down into what you collect but it's easy enough to separate them from your water.

I'm thinking ppm not to exceed 100 should be fine. My goal is 50 ppm or lower and that's with the DI phase of my RO disabled. My tap water (well) tests out well over 200 and most of that fancy bottled spring water tests out higher than the water of friends of mine who have city water. I don't buy bottled water any longer after seeing some of the readings obtained from my TDS meter. And it wasn't just one brand of spring water testing well over 100 either. It was every one I stuck my meter in.
 
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goldenrose

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I have that TDS meter, check ebay.
I ran out of rainwater at this time of the year, for the first time ever! Menard's had Glacial Mist purified water, .59/.64/gal. it read 00 on my meter. I refilled jugs at my local grocery store for .39 & that read 00 as well.
I got my gutters cleaned yesterday & it's raining now!
 
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