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Can we talk about fertlizer some more?

This is a discussion on Can we talk about fertlizer some more? within the General Orchid Culture forums, part of the Orchid Culture category; Howdy John. You make a good point about local water. depending on the water supply ...

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  1. #11
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    Howdy John.
    You make a good point about local water. depending on the water supply it may be beneficial to add calcium and sometimes there is enough in the water supply along with other trace minerals.

    As far as how much to add....That's why I lean more toward natural products like fish emulsion and seaweed extract. It's very hard to overfertilize with those.

  2. #12
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    depending on the water supply it may be beneficial to add calcium and sometimes there is enough in the water supply along with other trace minerals.
    i read somewhere that the calcium in tap water isnt available to plants ... is that correct?

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    Aerides is offline Senior Member
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    I'd like to know more about that calcium question. I am getting powdery residue on some plants. Based on a conversation with Robert at Robert's Flower Supply I am concluding that the RO formula I use is not a good match for my water after all - except possibly for my calcicolous paphs.

    Now which ones were those again ??

    Looking forward to trying my new tap-water formula, which has half the calcium.

  4. #14
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    list of calcicolous paphs at antec's site: www.ladyslipper.com
    scroll down and look for the "paph reading room" with their articles

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    i read somewhere that the calcium in tap water isnt available to plants ... is that correct?
    kewpie, yes, you're right. The calcium in tap water is usually calcium carbonate--very hard to dissolve or leach out unless you use a pretty acidic wash. That's why it precipitates out onto the plant leaves when water evaporates. It's much better to add in calcium nitrate--very available to the plants, and easy to leach out at the next watering if you added in too much.

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    welcome back, lja!! did you have a good weekend? your presence here was definately missed...

    back to the calcium...
    even though the calcium carbonate isnt readily absorbed by the plants, it still contributes to the TDS level, right? ive been poring over all the information in the antec reading room, and i read that its good to keep the TDS low. would adding calcium nitrate to tap water that already has calicium carbonate in it be bad for my orchids (because of the increase in TDS)? the precipitates of calcium carbonate are bad for plants, are they? i (like jmoney, pete, and heather) love paphs and phrags, and i know that they are sensitive to salt... does calcium carbonate count?

    thanks!

  7. #17
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    kewpie, thanks! Glad to hear I was missed, lol!

    So, as to your questions:

    Yes: calcium carbonate is not readily absorbed by the plants, and it does contribute to the TDS level.

    Calcium carbonate (unless we're talking about *extremely* hard water) is not so much "bad" for Paphs. and Phrags as it is useless. Keep in mind, though, that once it starts building up to the point that white crust starts to form, it'll effectively block light from the leaves and keep nutrients in fertilizer from reaching the roots as intended. For that reason, growers whose tap water is hard typically move to RO. My understanding is that dissolved solids anywhere over about 400 ppm is a situation that should be avoided.

    Precipitates of any ion (Calcium, Magnesium, etc.) are called "salts," but the salt you need to worry about is Sodium salt--table salt. Because water softeners use that to do their work, watering with "softened" water will kill orchid plants, so water softening is not a good way to "fix" hard water--water with excesssive carbonates. (For that matter, while I'm on it, never use coconut husk chips that haven't been soaked and rinsed several times over a period of days in your medium. The salt in those will destroy your plants.) So, yes, almost all orchids are very sensitive to buildups of Sodium salt especially, and any extreme accumulation of the otherwise "beneficial" salts found in fertilizer mixes in trace quantities will burn roots and leaves and sometimes even kill.

    Because calcium nitrate is much more soluble and easily flushed if it accumulates, I don't think that adding it to tap water (in the appropriate small quantities) would hurt anything--in other words, by using a fertilizer which contains it and mixing to the recommended dosage. But you might check with Antec before you take my word on that: I've only known growers to add calcium nitrate in specifically when they're using RO water and not tap. I don't want to steer you wrong.

    Finally, the last question (at least in my mind) is, "If Calcium Carbonate is useless as a form of calcium for orchids, why add something like crushed oyster shell whch is made out of calcium carbonate to the mix?" Here's why: the calcium carbonate will raise the pH, and, when dissolved in water that contains enough nitrogen from fertilizer, some will dissociate into its respective ions to recombine with the nitrogen into its much more useful form, calcium nitrate. "But wouldn't that also happen with the calcium carbonate in plain tap water?" Yes. That will absolutely also happen. And now we've hit the crux of the great debate: many very successful growers claim that using RO water and adding this and that into it is nothing more than a big waste of time and money, and that tap water that's fit enough to drink is certainly fit enough to grow orchids with, especially after you mix it with some decent fertilizer. This is a big, bad debate which has led to some serious name-calling....

    Hope this was clear; if it wasn't, let me know, and if I still can't explain it right, I'll find somewhere that explains it better and point you over

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    thanks, lja.

    i think i get it...ive been thinking of changing to distilled water from tap (even though i havent tested the water to see if its hard or not). i know that going to distilled water means that everything -- both beneficial stuff and non-beneficial stuff -- is taken out of the water.... but if there was enough beneficial stuff in regular tap water, what would be the point of fertilizing at all? if the TDS in the tap water doesnt help the plant and adding fertilizer to the water just adds to the TDS load -- which could hurt the plant, why not switch, right? just thinking out loud here...

    ive recently acquired calcium nitrate, and ive mixed a solution of 1/4 tsp. calcium nitrate plus 1/4 tsp. epsom salt in the same gallon of water. ive been using this about every 3 waterings (the 1st two waterings, i use 1/4 tsp dyna gro/gal, and in the 4th i flush with clear water) on all of my mixed collection. does anyone here see a problem with mixing calcium nitrate with epsom salt in the same solution? no poisonous fumes or explosions...so far.

    i think that everythings alright right now, but who knows...the only change that ive seen is that the red patterning on the leaves of my 2 psychopsis (which were fading away before) are coming back. by the way one of those two plants has a spike about 8" long and growing!!

    oh i just noticed something from aerides post:

    I am getting powdery residue on some plants. Based on a conversation with Robert at Robert's Flower Supply I am concluding that the RO formula I use is not a good match for my water after all - except possibly for my calcicolous paphs. Looking forward to trying my new tap-water formula, which has half the calcium.
    ok. deep breath (i know that ive been rambling on here)...
    lja (or anyone, for that matter): why should aerides use the tap water formulation with 1/2 the calcium if only the fertilizer calcium helps his plants?

    whew. thats all for now (i think)...

  9. #19
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    if there was enough beneficial stuff in regular tap water, what would be the point of fertilizing at all?
    kewpie, remember that we're talking about trace elements and micronutrients here, stuff that's measured in a couple / ten parts per million. The nutritional stuff in fertilizer (nitrogen, phosphorous, potassium) shouldn't be present in your tap water at anywhere near the concentrations you would use to fertilize with. (If it is, then it's time to call the Water Board, and 60 Minutes, for that matter...) Plus, fertilizer nutrients do more than just add to the TDS load and the benefits would certainly seem to outweigh the negative effects of that--I seriously doubt whether adding fertilizer to city tap water would increase the TDS to the "danger point," and distilled water for any kind of sizeable collection will get expensive fast.... But: if it's something you want to experiment with, I think you should!

    --No problem at all adding the calcium and epsom into the same gallon of water. But if you're looking to see some immediate change in your plants due to a new culture regimen, don't hold your breath. It could be months before you see any kind of noticeable difference.

    If I read Aerides' post correctly, he's going to use a fertilizer formula with half the calcium because he was getting mineral deposit buildup with the formula he was using before. In other words, the TDS in his tap water is very low, so he was using a fertilizer formula that was very high in minerals. But he started getting residue from that formula, so he's going to start using something with lower mmineral content.

    (Aerides, if I misunderstood you, please chime in and correct me here....)

    Anyway, unless you really like messing with mixing and measuring and things (which a lot of people do; the futzing makes them feel involved in their hobby), don't get too wrapped up over this calcium stuff. Until you can really know the levels and form of calcium intake for each and every calcicolous paph that you grow, it's all going to be pretty much hit and miss, and I don't want to give anyone the impression that you can't grow decent paphs without delving into the esoterica of orchid mineral intake...

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    Default Calcium stains on leaves

    Hmm. That is interesting. My tap water has 6.4-24.5 ppm calcium, and by all accounts is magnesium deficient. So I decided to try the MSU RO water formula, which is 8% calcium by volume (from calcium nitrate). I've now noticed something that looks like hard water stains on the leaves of my rhyncostylis (after the switch). I've also noticed a powdery residue in the leaf axils of my one of my phals (not mealybugs!). Is the extra calcium bleeding out onto the leaf surface? I have never had hard water stains on my plants before, since our tap water is very soft.

    Too much calcium now? Another vendor has a "tapwater" formula that has 4% calcium by volume that I may switch to. It is difficult to get a handle on what is actually in our water because it comes from more than one source. It is generally considered excellent. But my own measurements have indicated conductivity of 50 ppm (which is why I thought the RO formula would be a good match).

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