# Calcium and Magnesium



## consettbay2003 (Jun 30, 2013)

If I use equal amounts (by weight) of Magnesium Sulphate and Calcium Nitrate will that give me an acceptable ratio of Mg to Ca?


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## Rick (Jun 30, 2013)

Need to find out the waters of hydration of the materials you have access too.

Epsom salt is MgSO4.7H2O and half the weight is water. I use anhydrous MgSO4 so don't have to account for the water weight.

Same for calcium nitrate. There are probably 3 different forms available with differing waters of hydration.


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## Rick (Jun 30, 2013)

Also what is "acceptable ratio" for you?

Are you mixing this into tap/mains water (that already has a lot of Ca in it) or in RO water?

Are you amending the potting mix with lime or dolomite?

Overall I'd like to see a ratio from 2 to 4:1 Ca:Mg


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## Trithor (Jul 1, 2013)

And then in the very next thread, someone is advocating supplementing the plants with mag sulph to 'green them up'. If the correct ratio is 2-4 : 1, then why resuppliment with mag sulph? Just asking?


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## Rick (Jul 1, 2013)

Trithor said:


> And then in the very next thread, someone is advocating supplementing the plants with mag sulph to 'green them up'. If the correct ratio is 2-4 : 1, then why resuppliment with mag sulph? Just asking?




????? Not sure what thread is reffered to.

But since calcium is so common in the environment and many folks are adding lots of calcareous ammendments to their potting mixes, you can end up with much higher Ca:Mg ratios. That's fine for long term. 

But In general it's not a poor idea to chronically apply Mg at higher concentrations to Ca. But it doesn't hurt appying a couple shots for "greening things up".


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## Rick (Jul 1, 2013)

Trithor said:


> If the correct ratio is 2-4 : 1



I said that was my prefered ratio (not correct or absolute).

There's lots of slop in this ratio. But avoid spending time at ratios less than 1:1


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## Trithor (Jul 2, 2013)

Rick, sorry my comment was not directed at any particular thread and not more specifically at a thread of yours. Recently there has been a lot of talk about various macro and micro nutrients and then a whole range of values which each component should be supplemented in. The values change all the time depending on who is active in that thread (we seem to have a number of different camps here, the MSU traditionalists, the K-liters, the kelp and other naturalists, the no supplement anorexors, and a few other sects beside)
I am by no means new at growing orchids, but I recently discovered two near fatal errors in my culture that have relegated me back to newbie status. Firstly I use council water for all my plants, and supplement with RO and rainwater in the hope that I am improving the water quality somewhat. I use the word 'hope', because without knowing what you are starting with, that is the best that you can do, hope! I did have a test profile from the water division web-page and took that at face value. It was only after I organised my own water test that I realised that the profiles were very different. When I phoned the water division to query the result posted on their web page I was told that if I read the whole page I would see that they said it was a representative result of water tested at the time (no claim as to which water they were testing either), and that they made no claim as to its accuracy. The most important thing about what I am trying to say is that the majority of soluble fertilizers formulated for growing tunnel and agriculture are formulated with borehole/well water as the intended water source. As has been pointed out repeatedly, you need to know what your water contains! (I thought I did know, and thought that the posted result was reasonably accurate, I know suspect that whoever sent the water sample away, sent a bottle of bottled mineral water away!). Our council water contains almost no calcium and magnesium at all. This combined with using a fertilizer with no calcium and magnesium added to them, means that for years my plants were being starved of these two important elements. My supplementing the mains water with rain water and RO was only making the situation worse, not improving it. My second error was that I did not regularly check the TDS of my water after the injector to confirm there was no 'drift'. I did check the delivered concentrations when we installed the system, but failed to check it at regular intervals and so failed to realise that the fertigator had stopped working correctly.
Two huge errors which my plants are going to take a while to recover from. It is a problem which is made worse by the fact that my collection is too large for a hobby while I have a full time job, and too small to allow me to quit my job and run it as a commercial venture.


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## Rick (Jul 2, 2013)

Wild stuff Trithor.

I'm sure I'm totally spoiled with regards for knowing my water. For one, working in an aquatic tox lab (we get water samples from all over the country), and secondly, the US domestic water supplies are heavily regulated by local or state health departments (hence false quarterly updates would cause major legal ramifications).

In the US there is a wealth of good free data available on local domestic water supplies. Otherwise, from an orchid culture standpoint where reliable data doesn't exist, its best to start with rain or RO water and build up from scratch (as you have been doing).

Actually a 5-10% addition of Perrier water into RO would make a pretty nice base water.


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## Trithor (Jul 3, 2013)

I am quite partial to a 5-10% addition to my evening scotch as well


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## cnycharles (Jul 3, 2013)

Trithor said:


> I am quite partial to a 5-10% addition to my evening scotch as well



Ah, maybe you were reading the city water quality reports after having your evening scotch! 



Sent from my iPhone using Tapatalk


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## Trithor (Jul 3, 2013)

The stuff of nightmares, not something to contemplate over a pleasant tumbler, ever!


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## mango (Sep 4, 2013)

Hello.

All the paphs must have a good supply of calcium or just a few?
And also, I'm thinking to use crushed egg shells.

What do you think about it.

THanks.


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## Rick (Sep 6, 2013)

mango said:


> Hello.
> 
> All the paphs must have a good supply of calcium or just a few?
> And also, I'm thinking to use crushed egg shells.
> ...



All plants (not just orchids) need calcium and magnesium.

Unless you are watering with RO, distilled or rain water, there is plenty of Ca and Mg in your regular drinking water.

Calcium and magnesium shortages in plants are caused by excess potassium. So the best way to promote healthy uptake of calcium is to reduce potassium to environmentally realistic levels. (Less than 5 ppm).


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## Chicago Chad (Sep 6, 2013)

So Rick if I understand you correctly, you're are stating that a proper regular feeding amount of 5 ppm Potassium is important to reduce calcium and magnesium deficiancies when using distilled water, such as in my case?

Or is 5 ppm what you would suggest for all Paphs?


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## Brabantia (Sep 7, 2013)

I am curious to know how one decided the contents in Calcium and Magnesium in K-Lite fertilyser (same for MSU which as the same content for these two). At 65 ppm N for these two fertilysers we have a solution having a content of 15 and 50 ppm Ca and Mg respectively. Here in Belgium the AKERNE society sells a substitute for MSU (AKERNE RainMix) which gives respectively 40 and 9 ppm of Calcium and Magnesium at 65 ppm N. Discussing with the seller he said me that it is risky to use a hight concentration in these two elements because we can have an exaggerated leaves hardening and in the case of plants such as Masdevallias a difficulty for leaves to go out of their shield. This is the reason why they have decrease a little bit the content in Ca and Mg of the AKERNE RM. Your comments about this subject will be very appreciated. 
Thank you in advance.


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## Stone (Sep 8, 2013)

Rick said:


> > Calcium and magnesium shortages in plants are caused by excess potassium.
> 
> 
> 
> But if you are using a fertilizer without these 2 elements and rain water, then the shortage is due to lack of these elements not K. Also many plants (as discussed elsewhere) can take high K amounts without the Ca/Mg becomming deficient. Without going over the same ground again, as an example, my lowii, philippinese, roths etc are doing great with 'normal' K (about 0.5:1 K/N)


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## mango (Sep 8, 2013)

Ok, I understand.
THanks you.


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## Rick (Sep 8, 2013)

Brabantia said:


> I am curious to know how one decided the contents in Calcium and Magnesium in K-Lite fertilyser (same for MSU which as the same content for these two). At 65 ppm N for these two fertilysers we have a solution having a content of 15 and 50 ppm Ca and Mg respectively. Here in Belgium the AKERNE society sells a substitute for MSU (AKERNE RainMix) which gives respectively 40 and 9 ppm of Calcium and Magnesium at 65 ppm N. Discussing with the seller he said me that it is risky to use a hight concentration in these two elements because we can have an exaggerated leaves hardening and in the case of plants such as Masdevallias a difficulty for leaves to go out of their shield. This is the reason why they have decrease a little bit the content in Ca and Mg of the AKERNE RM. Your comments about this subject will be very appreciated.
> Thank you in advance.



The MSU and AKERNE formulations were based on leaf tissue analysis of plants exposed to "traditional agricultural usage levels" of K. Upon examination of these leaves (which is pretty much the same for the Cornell study done in the 1970's, and just about any agri study with food crop plants) the amount of Ca and Mg was reduced relative to N and K. Also as K exposure increases the Ca and Mg goes down. At what point you will experience acute symptoms of Ca and Mg "deficiency" symptoms will vary based on the tolerance of the plant. However, I have also suggested that a lot of sublethal effects (such as general slow growth, susceptibility to disease, and bud blast) can also be symptomatic of low tissue Ca and excess K. 

Now if you pull leaves from jungle grown plants (not exposed to agriculture levels of K) you generally find that the amount of Ca is considerably higher than K and sometimes higher than N. 

Ca is almost always more available in the environment than K.

I have pointed to a handful of successful growers that have never used supplemental feed using irrigation water with hardness in excess of 200ppm (as CaCO3). 

With very elevated levels of Ca (especially as carbonates) there is a possibility of magnesium and phosphate deficiency. So if you run systems with lots of calcareous buffer you should probably be concerned with supporting a bit extra Mg and Phosphate (a bit more sulfate probably wouldn't hurt either).

I don't grow a lot of pleuros and masdes, but I have been getting some good results lately since reducing light in my pleuro box. I'm also about to get blooms on my first Masdevalia ever (an infracta). Leaf growth has been excellent. I would say that ratios aren't that important when the conductivity of the total feed mix is around 50 uS/cm.

I have been feeding at the rate of about 5ppm N with a hardness of ~ 25-35 ppm (as CaCO3). Phosphate about 5ppm, and K is probably less than 1ppm. The pleuros (genus Pleuro, Resptrepia, Masdevalia, Stellis) are doing good.


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## Rick (Sep 8, 2013)

Stone said:


> Rick said:
> 
> 
> > Also many plants (as discussed elsewhere) can take high K amounts without the Ca/Mg becomming deficient. Without going over the same ground again, as an example, my lowii, philippinese, roths etc are doing great with 'normal' K (about 0.5:1 K/N)
> ...


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## Stone (Sep 8, 2013)

Rick said:


> Stone said:
> 
> 
> > Especially if you flush the heck out of them with low K water between feedings to wash it all away:wink:
> ...


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## Rick (Sep 9, 2013)

Stone said:


> Rick said:
> 
> 
> > K is continually being released from the osmocote in the pots oke:
> ...


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## Stone (Sep 9, 2013)

Rick said:


> Stone said:
> 
> 
> > So how are you calculating your continuous/weekly/monthly K exposure concentration?
> ...


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## keithrs (Sep 9, 2013)

Stone said:


> Rick said:
> 
> 
> > Me calculate? Its all guesswork:evil:
> ...


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## Rick (Sep 10, 2013)

Stone said:


> Me calculate? Its all guesswork:evil:



For instance if you are using the 19-6-12 Osmocote that recomends adding 3 tablespoons per 2X2' square (about every 4 months). That comes out to about a 1/4 tsp per 4" pot.

by the time you adjust for total available K per gram of Osmocote, spread out over 4 months, that comes out to a much smaller dose compared to the old fashioned "weakly weekly" feeding of a traditional liquid high K fert at 100ppm N.

Now the Osmocote feed is in prills that may or may not be in contact with roots, so dispersed only by watering( which in your case is with almost no K water). So watering may wash the fert out of the pot more effectively than when using a liquid feed that saturates the spongy potting media. 

So you may be providing a lot less K (or anything actually) than you think you are.


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## Brabantia (Sep 11, 2013)

Thank you Rick for your answer, but it is not so much the concentration in K (in KLite or other low K fertilyser)that worries me but the extreme hardening risk of leaves and their envelope when the quantities of Calcium and Magnesium distributed are too well hight ( 20 ppm Mg and 50 ppm Ca at 65 ppm N). I understand definitely that ratio N/K is too much low in MSU and Akerne fertilyser (to say in another way: too much K in comparison with nitrogen content).At these conditions I have observed very hard leaves on Phalaenopsis hybrids and leaves crooked and freeing itself hardly of their envelope for Masdevallias.


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## Rick (Sep 11, 2013)

I've been feeding at 5ppm N and not seeing problems with over hard leaves. I'm just not finding any justification to apply nitrogen (via nitrate or ammonia) at concentrations over 5-10ppm for masdevalias. Even if Ca is 10-15 ppm with N down to 5 ppm seems fine.

Compared to high K results my plant leaves have much harder/ firmer substance (including Phaleanopsis) as tissue Ca increases. This seems to deter mealy and scale bug problems. I am not seeing leaf crippling in the pleurothalids that I can attribute to Ca overdose.


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## Brabantia (Sep 11, 2013)

Rick: at which frequency do you feed at 5 ppm N?


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## Rick (Sep 11, 2013)

Brabantia said:


> Rick: at which frequency do you feed at 5 ppm N?


 Daily to every other day.


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## Rick (Sep 11, 2013)

For clarification Brabantia:

MSU pure water 13-3-15 8Ca 2Mg
K lite 12-1-1 10Ca 3 Mg
Akern rain 13-3-15 11Ca 3Mg

They are almost all the same as far as N to Ca/Mg goes, and actually the old MSU pure water has the least Ca compared to N.

If the question was adding even more Ca and Mg (either by pot ammendments or to the feed) was detrimental to Pleurothalids when using these feeds, I would generally agree. In fact I see no reason to use supplemental Ca/Mg for any orchid with these feeds either in the feed or in the potting mix.

I have found lately that some additonal P and Mg has helped green plants up where calcerious pot supplements seem to be causing yellowing with K lite use.


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## Brabantia (Sep 12, 2013)

Rick said:


> Daily to every other day.



5 ppm N daily ... is it the same as 30 ppm per week? Do you use an inert (mineral) substrate?


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## Rick (Sep 12, 2013)

Brabantia said:


> 5 ppm N daily ... is it the same as 30 ppm per week? Do you use an inert (mineral) substrate?



If you don't consider how much gets held up (or flushed out) in the media you are correct.

My mixes do use considerable large limestone chips, which are probably more inert than LECA. I also have a lot of mounted plants which offer very low storage volume to surface ratios compared to potted media conditions. Consider the amount of K held up in various media data that Xavier presented.


All media held up considerable K over the year or two of application. Despite all getting fed the same rate,the Orchiata bark stored the lowest, while I think sphagnum stored the most.

So I think by frequent very dilute feedings (rather than periodic heavy feedings) the equilibrium will ultimately favor much lower total exposure of nutrient, and a more favorable diversity of microflora.


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## Stone (Sep 13, 2013)

Brabantia said:


> 5 ppm N daily ... is it the same as 30 ppm per week? Do you use an inert (mineral) substrate?



It might be more accurate to say ''whenever you water'' or ''every second watering'' etc. So if you have determined the optimum fert rate for every watering, you need to double that for every second watering and quadruple for every forth watering. 
But the longer you leave between feeding the greater the risk of too high salinity. So I agree with Rick that more often but weaker is probably best. But I would add that you still need to flush well from time to time. Large volumes of water 3 times but 2 hours apart ( to allow time for everything to go back into solution) would be good and you can feed again straight after that if you want to bring the EC back to where you want it.


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## Ray (Sep 13, 2013)

I think that media play a role in our feeding regimen, but sort-of in a "converse" role to what most folks think (because they're used to terrestrials in soil).

In my opinion, most orchid media do not contribute appreciably to the plants' nutrient supply. However, they can sequester nutrients, throwing off the "balance" we think we have achieved. Then, over time, they become so saturated with those minerals and waste products that they are the veritable overfilled-balloon, and - ka-pow! - dump them back into the environment at outrageous concentrations.

That would imply that a totally inert, open and non-absorbent medium, coupled with very frequent, diluted fertilizers solutions, would be the ideal.

Maybe it's time for some additional experimentation. Marbles? Ceramic ball-milling media?


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## Rick (Sep 13, 2013)

Ray said:


> Maybe it's time for some additional experimentation. Marbles? Ceramic ball-milling media?



Yes, marbles would be about as inert as you can get. Or trying full hydro?

I was remembering our threads with RB down in Florida with her Catts and Hoyas, and how she was ramping everything up to offset nutrient deficiencies (?!?!).

I recently got some hoya stem cuttings and stuck them in cups of my well water. No media, no feeding. In 3 months getting fantastic root growth and one cutting is now in bud!


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## terryros (Sep 13, 2013)

I always think that these full hydro stories with orchids tell us that it isn't roots being too wet in sphagnum (or other substances) that is a problem. It must be something wrong with the chemical balance that causes problems with the roots, like becoming too acidic in sphagnum. I don't hear that people are doing anything special to get oxygen to the roots in these hydro setups, either. Is there any oxygen uptake at the root zone or is all gas exchange through leaf stomata?

Perhaps having the right EC, pH, and nutrient balance in the surrounding fluid is what is most important for the roots.


Sent from my iPad using Tapatalk HD


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## Rick (Sep 13, 2013)

terryros said:


> Perhaps having the right EC, pH, and nutrient balance in the surrounding fluid is what is most important for the roots.
> 
> 
> Sent from my iPad using Tapatalk HD



That's exactly what I've been thinking.

I recently saw a hydroponic system that keeps O2 high at the roots. The plants are suspended over a tank of hydroponic solution that has a pump and spray bar on a timer. Depending on how you set the timer, the roots are sprayed periodically, but in generaly they just hang over the nutrient tank.

How different is that from my mounted plants that I spray every day? My vandas aren't even on mounts, just a basket with bare roots hanging down. I spray almost daily with a nutrient solution EC strength of 50 to 100uS, and I've never done better!!


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## Stone (Sep 14, 2013)

Ray said:


> > That would imply that a totally inert, open and non-absorbent medium, coupled with very frequent, diluted fertilizers solutions, would be the ideal.
> 
> 
> 
> ...


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## Ray (Sep 14, 2013)

My only concern with marbles is that soda-lime glass can be pretty alkaline. Probably not really an issue with such small surface area, unlike Growstones.

I DO know that glass is leachable though. Water reacts with the alkaline elements - Na, for example, forming NaOH that dissolved the silica structure, releasing everything.

It is a really slow process though - I have a prohibition-era whiskey bottle recovered from Long Island Sound by a scuba-diving friend, and it is iridescent, courtesy of the undermining of the surface by that chemical process.

So I guess that means that marbles would not be a good choice after the first 70 or 80 years.


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## Stone (Sep 14, 2013)

Ray said:


> > So I guess that means that marbles would not be a good choice after the first 70 or 80 years.[/
> 
> 
> 
> Yes after that you would need to re-think it.


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## ALToronto (Sep 15, 2013)

Ray, such leaching is unlikely to happen since most fertilizers turn the water slightly acidic. Glass is ok up to a pH of 10 or so (unless it's Pyrex, then it can't handle any alkalinity). But even Pyrex is unlikely to disintegrate in our lifetime, or raise the pH enough for orchids to notice. I also suspect that glass-making technology has improved somewhat since that whiskey bottle was made.


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## Ray (Sep 16, 2013)

Alla - This issue with glass and water is not the necessarily the pH of the solution, it's the presence of alkaline materials within the glass itself, allowing the water to react and form the alkaline solution locally and internally. However, it is a very slow process of dissolution and degradation. 

(I happen to be a ceramic engineer and scientist, and have worked with the glass industry much of my career, starting in product development for Corning. The glass in a modern bottle is pretty much chemically the same as it was 100 years ago - it works and it's cheap...)


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