Lime loving Phrags and Phaphs question..

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SEMO-Cypr

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The more I read on these threads the more I realize I don’t know near enough to make these plants thrive.

Does someone have a list of species that need lime added to their media? I planned to add crushed oyster shell or some dolomitic lime to the plants media that need it. Or could I just add Cal/Mag to my water schedule and just take care of it that way?
 

Ray

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All plants must have calcium while in active growth.

Most nutrients, once absorbed, can be translocated to newly-growing tissue as needed, but calcium tends to be relatively immobile. Many municipal and well-water sources have plenty, so it's not an issue. Personally, I simply use a fertilizer that contains calcium and magnesium and don't give it a second thought.
 

geoffsharris

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Calcicolous Slippers has which plants are calcicolous vs. not. This doesn't necessarily mean that they require supplementation, but does suggest which plants are going to be the least tolerant of an acidic root zone. The need for supplementation with oyster shell or dolomitic lime is probably more related the the pH of your irrigation water and how much calcium you are supplying with your fertilizer program (combo of what's in your water and fertilizer). Once I stated to report every 12-18 months, adding oyster shell seemed less relevant to getting good root growth. My irrigation water with fertilizer is about pH 5.9 and 30-40 ppm calcium. If you grow in bark, the longer you go, the lower the pH will go as the bark starts to break down. Adding dolomitic lime or oyster shell can counteract the pH change of bark breakdown or low pH irrigation water to some degree. Lots of calcium, but an acidic root zone is much more of a problem than a bit less calcium than ideal, but a proper root zone pH.
 

SEMO-Cypr

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Ok, thanks for all the responses, I do use CalMag once a once in my fertilizing regimen, but I usually only give about 20ppm. I use rain water so other than whatever is coming off my roof into the rain barrel there isn’t much minerals in the water. Usually my rain water is between 4-18ppm depending on the time of year and then I add 80-100ppm of MSU and then once a month 20ppm of CalMag. I think I’ll be adding some oyster shell to my mix in my next repots.
 
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One thing I’d like to offer RE: calcium: I’ve noticed that I see some negative effects when I feed Cal-Mag to plants during heat waves. I’ve gotten screwed 3 times by feeding and then suddenly the forecast changes and it’s blazing, which means temps of 90F+ in my house. I do Ray’s K-lite but then I supplement Cal-Mag a few times in March to May, then a few times late September to November. Oyster shell I do once a year, mid spring. So much of it washes out that I wonder how much of a benefit it actually provides.
 

Ray

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I’m not sure how much we can put into whether a plant is growing in calcarious or non-calcarious substrate needs more calcium or not. There is likely a great deal more to how plants came to be growing in a particular location than the availability of a single mineral.

Phosphorus compounds are typically quite insoluble in calcarious substrates, so maybe plants’ preference is a desire to avoid that, rather than a desire for more Ca. (Frankly, I think that’s less likely, as calcium is more critical to growth, but I can’t definitively rule it out, either.)

Tissue analysis doesn’t tell us if a plant “needs” something, it only tells us what it has gotten.

There are plants that grow on granitic outcroppings, but there is no evidence they need extra silica.

I’ll add that I have grown plants on that list that are “calcicolous” and not, side-by-side, using an identical inert medium and fed under the same nutritional regimen, and they have done well.

One thing I’m unclear about - does a dose of oyster shell really play the Ca-supplement or pH-stabilization role we think it does? Oyster shell is pretty insoluble in water.
 
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Ray

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For all of my kovachii and their hybrids, I adjust the ph of my feeding solution to 7.5. They seem to do better than befor I started doing that.
If you’re up for a little task to help satisfy my curiosity, try trickling some pure water (distilled or RO) through the pot - just enough to collect about 3 tablespoons of drainage from the pot bottom - and test the pH of that.
 

geoffsharris

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Kovachii is a good example of a plant that really resents a low pH media. The initial flasks that people got were deflasked into sphagnum which has a low pH. It was a disaster for growing them. I have no doubt that through a combo of media and irrigation water they prefer to be on the more alkaline end of the orchid spectrum.
 
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If you’re up for a little task to help satisfy my curiosity, try trickling some pure water (distilled or RO) through the pot - just enough to collect about 3 tablespoons of drainage from the pot bottom - and test the pH of that.
Ok, give me a couple days
 

SEMO-Cypr

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For all of my kovachii and their hybrids, I adjust the ph of my feeding solution to 7.5. They seem to do better than befor I started doing that!
So Kovachii and their hybrids prefer more calcium. Is there is list of calcium loving species VS none calcium loving species out there? I was gifted a LARGE collection and just trying to make sure I water and feed correctly and add oyster shell to mixes when I repot. And yes I know all plants need some calcium…
 

Ray

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Preferring a certain rhizosphere pH and needing more calcium are not necessarily synonymous.

I am still interested in the oyster shell solubility question. Online research I’ve seen suggests it’s insoluble in water unless it has been acidified. If the pH preferred by kovachii and it’s hybrids is 7.5, it’s unlikely oyster shell additions contribute much, if anything.

I kind of feel like I’m beating a dead horse here, and PLEASE don’t think I’m shooting down individuals’ culture. I’m just trying to get the facts of the matter.
 

geoffsharris

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Preferring a certain rhizosphere pH and needing more calcium are not necessarily synonymous.

I am still interested in the oyster shell solubility question. Online research I’ve seen suggests it’s insoluble in water unless it has been acidified. If the pH preferred by kovachii and it’s hybrids is 7.5, it’s unlikely oyster shell additions contribute much, if anything.

I kind of feel like I’m beating a dead horse here, and PLEASE don’t think I’m shooting down individuals’ culture. I’m just trying to get the facts of the matter.
Agreed Ray that root zone pH and calcium can be related and that adding calcium to irrigation water does not equal a higher irrigation pH nor does adding oyster shell mean adding available calcium to a plant. As I understand it kovachii both appreciates to be fed higher calcium levels and appreciates a generally higher root zone pH. The fact that both can be accomplished with dolomitic lime is why I use some on my plants. I have added oyster shell mostly to act as a buffer to low pH with a secondary release of calcium as a byproduct of the buffering capacity. I have also used coral gravel (well washed to remove salts). As long as the pH is high enough, oyster shell is functionally inert and minimally soluble in water. Only once a mix starts to drift toward an acidic state the organic acids react with the CaCO3 to release H2O, CO2 and Ca. Is does this by soaking up two H+ ions. Orchiata is notorious for being a great media for 2ish years and then nuking the roots as the pH plunges. This is why they add micronized dolomitic lime to it. The oyster shell and coralline gravel functionally do the same thing for much longer than the lime it comes with. I've found adding oyster shell or gravel a lot less important to maintaining good roots once I started repotting paphs and phrags every 12-18 months.
 

Ray

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I grow in 100% inorganic media, so the plants and the microbes are what determines the rhizosphere pH.

I have a couple of kovachii hybrids are are growing like weeds, so I’ll just keep up my K-Lite/Kelpak/Quantum regimen.
 

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