Crushed oyster shell top dressing Paphs

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Anca86

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Hello,

Do Paphs need crushed oystershell top dressing?
Thanks
 

musa

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Paphs need some form of CaCO3, first to regulate the pH-value, second as a source of calcium. In nature many Paphs grow on limestone (not all!). What form you use, oyster shell, egg shell, dolomite powder limestone gravel, marble gravel... is up to you, whatever fits best to cour culture and conditions.
 

Anca86

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Paphs need some form of CaCO3, first to regulate the pH-value, second as a source of calcium. In nature many Paphs grow on limestone (not all!). What form you use, oyster shell, egg shell, dolomite powder limestone gravel, marble gravel... is up to you, whatever fits best to cour culture and conditions.
Thank you for your reply:)
 

richgarrison

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i do both, some in the mix as i repot, and finally a top dress... chicken grit (sometimes referred to a as oyster shell, although it isn't 100% oyster shell)... i pay 10$ for a 40lb bag at my ag supply.

and while you are at it, Orchid Zone back in the day was a fan of including some sand in their mixes. The sand they used was the sand used in pool filters, not just any sand. Not very much, but i sprinkle a little of that in the pots as i am repotting also...

Putting that stuff in the mix itself and then repotting, in my experience, has lead to most of it sitting in the bottom of the mix container, and not very much making it into the actual pots... Hence me adding it as i repot. Makes the repotting exercise feel a little more like cooking :)
 

Happypaphy7

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It is not necessary.
The whole adding oyster shell/dolomite to the potting mix thing came from the fact that many species are found in the wild where lime stone is very common. Often, the entire area!
While many species have their roots on direct contact with the rock itself, the roots are often covered with many organic debris and dirt as well as live moss. Others are not in direct contact with the rock at all where there is a layer of soil and organic matter over the rock bed in which the roots grow. The pH at the root zone is actually near neutral or slightly acidic.

Now, some Paphiopedilums I purchased came with little bit of crushed oyster shell mixed in the potting mix.
Others (almost all) came without any of that. They seem perfectly fine either way. When I repot them, I do not use oyster shell or lime stone.
 

werner.freitag

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the calcium is just one part of the puzzle
and it is in the mix, in the fertilizer , in the water and...............
 

SuperPaph

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I use to add small limestone pieces in medium, besides a small quantity of crushed shells, which will stabilize the adequate pH near roots, and will act like a "tampoon" stabilizing, excusing the repetition.
 

Ray

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The simple fact is that plants must have a source of calcium while in active growth. That calcium must be in ionic form in solution in order to be taken up by the plant.

Look at the water solubility oyster shells, limestone, gypsum, dolomite, marble, egg shells, etc., etc., and compare them to that of calcium nitrate, which is used in many fertilizers. Relatively speaking, they are quite insoluble.

That said, there are two things that stop me from saying “they don’t work”. One is the fact that the mass of calcium ions needed is not huge, and the other is that none of those potential supplements is totally insoluble, so they must be contributing something. My question is “is it enough?”, and rather than risking a deficiency, I think it’s better to use something I know contains a truly soluble source.
 

Anca86

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The simple fact is that plants must have a source of calcium while in active growth. That calcium must be in ionic form in solution in order to be taken up by the plant.

Look at the water solubility oyster shells, limestone, gypsum, dolomite, marble, egg shells, etc., etc., and compare them to that of calcium nitrate, which is used in many fertilizers. Relatively speaking, they are quite insoluble.

That said, there are two things that stop me from saying “they don’t work”. One is the fact that the mass of calcium ions needed is not huge, and the other is that none of those potential supplements is totally insoluble, so they must be contributing something. My question is “is it enough?”, and rather than risking a deficiency, I think it’s better to use something I know contains a truly soluble source.
Thank you, Ray
I asked because I just received a Paphiopedilum appetonianum and I've read that one must put a top dressing of oyster shell.
 

Brabantia

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Materials that contain Calcium such as dolomite, crushed shells, coral ... should not be considered as sources of Calcium but rather as neutralizing agent of the the substrate acidity which develops with the aging of the substrate.
 

Brabantia

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What would be a good ph for paphiopedilum?
I would say between 6.5 and 7. If, despite the addition of basic substances, you notice that the pH remains acidic (typically 5.6 or lower) , I advise you to repot in a fresh substrate. Your substrat is too decayed.
 

Anca86

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I would say between 6.5 and 7. If, despite the addition of basic substances, you notice that the pH remains acidic (typically 5.6 or lower) , I advise you to repot in a fresh substrate. Your substrat is too decayed.
Thank you for the information.
 

Ray

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Be aware that the pH of the solution you apply is not likely to play a very great role in the pH of the medium, and that's what's important.

If you want to know the pot pH, do the "Pour-Through" test:

  1. Water the pot with your solution-of-choice.
  2. Wait 30 minutes, allowing the pot to thoroughly drain and for the chemistry to equilibrate.
  3. Trickle about 50 ml (I use a shot glass, as it's quite handy) over the surface of the medium and collect the drainage.

    THAT's the pH to test.
 

Anca86

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Be aware that the pH of the solution you apply is not likely to play a very great role in the pH of the medium, and that's what's important.

If you want to know the pot pH, do the "Pour-Through" test:

  1. Water the pot with your solution-of-choice.
  2. Wait 30 minutes, allowing the pot to thoroughly drain and for the chemistry to equilibrate.
  3. Trickle about 50 ml (I use a shot glass, as it's quite handy) over the surface of the medium and collect the drainage.

    THAT's the pH to test.
Thank you,Ray.
 

Anca86

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Be aware that the pH of the solution you apply is not likely to play a very great role in the pH of the medium, and that's what's important.

If you want to know the pot pH, do the "Pour-Through" test:

  1. Water the pot with your solution-of-choice.
  2. Wait 30 minutes, allowing the pot to thoroughly drain and for the chemistry to equilibrate.
  3. Trickle about 50 ml (I use a shot glass, as it's quite handy) over the surface of the medium and collect the drainage.

    THAT's the pH to test.
Hi Ra
Be aware that the pH of the solution you apply is not likely to play a very great role in the pH of the medium, and that's what's important.

If you want to know the pot pH, do the "Pour-Through" test:

  1. Water the pot with your solution-of-choice.
  2. Wait 30 minutes, allowing the pot to thoroughly drain and for the chemistry to equilibrate.
  3. Trickle about 50 ml (I use a shot glass, as it's quite handy) over the surface of the medium and collect the drainage.

    THAT's the pH to test.
So...today I measured tge ph for my paphs and phrags. For paphs I got around 7 with a max of 7,15. For Phrags, also around 7 but the mas is 7,40. I don't quite know what to think about this.
 

Ozpaph

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Ray, why is 'pour through' better than part submerging the pot in RO water, waiting, then removing the pot and taking the measurements? Surely allowing plenty of time for the potting mix to equilibrate with the water better reflects what's going on in the mix?
 

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