Oyster Shell for Orchids
 

Please, those who have experience with oyster shells, could you explain its use, benefits, for which plants, and in which substrates it would or should not be used.

Thanks!

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Oyster Shell provides extra Calcium to orchids. When I joined my orchid society, most of the members at that time were really fond Paphs and they all used crushed oyster shell once a year for their Paphs. They would remind each other at the right meeting that it was the time to do it. I do not grow Paphs so I never paid much attention. I do know that some members grew in LECA, some grew in bark mixtures, some grew in a medium made of some recycled material(?) bought from a man here in Ohio who bred Paphs for the florist industry and some grew in rock wool. The oyster shell was bought from a local orchid vendor so we knew it was salt-free. I use it in little bonsai baskets for my Cattleyas that are potted in lava rock (without the little baskets, it would fall through).

As a general rule, it is best to "perfect" all of your other cultural parameters before even thinking about messing with nutrition.

Before using any additive for adding calcium, be sure you need to. The first things to ask yourself is "how much is already in my water?" and "might it be coming from other sources?".

Calcium, magnesium and potassium "compete" for sites within the plant. Adding excess of one can preclude the absorption of the others.

Plus there's the fact that oyster shell really isn't all that soluble in water, so the contribution it makes is negligible.

Hi guys! Thanks for the comments

In my particular case @Ray, I think I cover the nutrients as normal-advance possible. For example: I only use RO water and a 20.20.20 Fert, Kalmax once a month, and if the plant is super down I use like one shot of Superthrive.

But one of the best vendors here in Europe used the shelf a lot, all my plants come with some shells. So, I was wandering....

It clearly said in the package that is to be mix in the medium and has a very slow release.

Hey Sade,
I'm a complete noob and all but if you're talking about Schwerter, it seems like they used the shells for a while to prevent the growth of algae.

I was confused about it, too, when I got a Dendrobium Cuthbertsonii with these shells on top and I think I found that information on a german forum.

I didn't ask them myself, though, so please take it with a grain of salt lol.

From a chemistry point of view the amount of calcium leaching out of dolomite chips, oyster or egg shells into the medium is close to zero. Far more calcium is in most people's tap water. If it's not, a calcium supplement is necessary.

I use marble chips in the mix with my European terrestrials - verrry sloooww release calcium to mimic calcareous soils, since I'm use RO water. Whether it actually does anything I don't know...

Geology of Palma de Mallorca consists of a lot of limestone and dolomite. Your water supply probably reflects that; you shouldn't need extra calcium or magnesium.

You can get some information on water quality from tappwater co/en/tap-water-mallorca-palma-filter I'm sure there's a Spanish version of the same web page, that is just what comes up in my browser.

The water is hard, with a high mineral content. You may even need to dilute it with rain water or reverse osmosis water to reduce dissolved solids.

Thanks for look up!
For garden plants; catts, dend, oncis and cyms, I use like 80% RO ans 20% tab water, mainly because the report that I could get (not as good as in the states) indicated a high concebtration of sodium hypochlorite (clorox) and well.... But if I have to use tap water I don't panic.

BUT, for Phap, Mini species, Masdies and Dracs, I dont even think about using tap water, so the extra Mag & Cal was mainly thinking for those groups.

---------- Post added at 02:11 AM ---------- Previous post was at 01:57 AM ----------

Yeah, Schwerter it is!
I ask them and I didn't get any explanation about algaes, but now that you mentioning is true that I never see algaes in their plants, at least not as much of others.

My whole research is beacusd they even send me a little bag of cruches shells and an other one with dolomite as a gift. The only advice was to mix the shells with the Phals and Phap and use the dolomite every 2-3 month 1gram per liter of water for dracs and masdies. They also clearly said that does not dissolve but that release passively.

What I have learned is that sometimes, professional growers have learned a few tricks over the years about growing certain plants and they might generously, helpfully, share this information as they pass along the plants.
That is what is happening here. The vendor must really believe in this advice if he is even supplying you with the oyster shell.

It is really your choice, though, if you want to follow this advice or follow what has always worked for you in the past with these types of orchids. As long as you understand any differences between the new hybrids/species and the ones of that type you are already growing, you can make the right adjustments for your own growing conditions.

Good luck with your new plants!