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Orchid Fertilizer

Discussion in 'Introduce Yourself' started by TripleMochaFrap, Nov 23, 2019.

  1. TripleMochaFrap

    TripleMochaFrap New Member

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    Hi, this is my first post on this forum and I am fairly new to growing orchids. I just purchased Jack's fertilizer because it is highly recommended by many orchid growers, however I am quite confused on how I should dilute it. Websites state that I should apply a 1/4 dilution of the standard strength recommended on the fertilizers label and water with this weekly. The label on the fertilizer container says I should add 1/4 of a teaspoon to a gallon of water for indoor plants so does that mean I must use 1/16 of a teaspoon? It seems a bit too little but I really don't want to over fertilize my plants.
     
  2. Ray

    Ray Orchid Iconoclast Supporting Member

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    Orchids, being slow growers of the plant world, a fairly undemanding of fertilizer.

    Nitrogen is the important element in any fertilizer, so that is how most professional growers manage their applications.

    For weekly application, I recommend a nitrogen concentration of about 100 ppm N. If you divide 8 by the %N on the fertilizer label, the result is the teaspoons/gallon for that level. It is fine to round it a bit for convenience.
     
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  3. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I've never really worked with the ppm of nitrogen, just the total ppm since that is what my ppm meter will measure. Many fertilizer labels recommend 1 tsp per gallon. Which makes sense if you keep in mind that they are in the business of selling fertilizer. I think Jack's is more conscious of what orchids need. I use 1/4 teaspoon per gallon and it works for me growing in a greenhouse. The brighter the light, the more fertilizer the plant can use. So in the summer I use the 1/4 at each watering and in winter I decrease the concentration. If you are growing on a windowsill, your light may be lower that in a greenhouse, so you might not want to fertilize as often as I do. If you are growing under lights, that will also be different.

    Over time you will get a sense of the balance between light and fertilizer. Generally, if your plants are a very dark green it is too much fertilizer/not enough light. If they are very light green it would be reversed. Some plants have naturally lighter or darker leaves. Part of it is experience, seeing other people's plants and watching what is happening to your plants.
     
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  4. TripleMochaFrap

    TripleMochaFrap New Member

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    Thank you SO MUCH, this cleared all my confusion and was so helpful!
     
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  5. Ray

    Ray Orchid Iconoclast Supporting Member

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    What a lot of folks don't seem to grasp is that the TDS reading varies widely with the formula of the fertilizer.

    If you know the calculated nitrogen concentration, then measure the TDS of the solution, the TDS becomes a great control factor, but if you arbitrarily choose a certain PPM TDS, then your feeding regimen might be too little or too much, and will change if you change fertilizer.

    100 ppm N K-Lite might have a TDS of about 250-275 ppm, while 100 ppm N of MSU WW formula might be closer to 500 ppm TDS.

    Marni, what TDS does 1/4 tsp/gal (a shade under 100 ppm) of Jack's add to your water supply?
     
  6. TripleMochaFrap

    TripleMochaFrap New Member

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    Just to be sure, I purchased the standard fertilizer which is 20-20-20 and I ended up with 0.4 as my teaspoons/gallon. Should I round that to half a teaspoon per gallon because it'll be a bit hard to measure that out.
     
  7. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I don't use Jack's, I use MSU for RO. And I try for 160 total ppm. I am about to install a mixer as the injector pump causes the ppm to vary in a cycle as it pumps in and then is diluted.
     
  8. Ray

    Ray Orchid Iconoclast Supporting Member

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    Marni, if you're metering pump has a variable mixing ratio, try halving the concentration of the feed and doubling the amount metered. If that's not possible, putting the injection point farther from the delivery end of the hose can help, too.
     
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  9. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    This did become more noticeable when I started using a more concentrated solution. I'm hoping the mixer will even it out so I don't have to go back to mixing it so often.
     
  10. Ray

    Ray Orchid Iconoclast Supporting Member

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    I had another thought: A mixing chamber.

    My first thought was a complete DIY project - a 2' long piece of capped 4" PVC pipe with a male and female hose fittings at either end. As the solution enters that volume, it will get mixed by its own turbulence and the outflow will be much more uniform.

    Alternately, and easier to do, is to purchase a large filter housing (20" x 4" with at least 3/4" NPT threads to minimize pressure drop), add the hose fittings, and you're set to go. I'd run it "backwards" from the labeled flow direction so the input blasts down from the center of the cap for better mixing. I've seen Pentek "Big Blue" housings available online for under $40.
     
  11. Marni

    Marni Well-Known Member Staff Member Supporting Member

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    I've thought about making something like that. In the end I bought a "static mixer" that gets installed in line after the proportioner(s). Screen Shot 2019-11-27 at 5.14.55 PM.png