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What's a good fertilizer?

This is a discussion on What's a good fertilizer? within the General Orchid Culture forums, part of the Orchid Culture category; Hey all... I need a recommendation for a good all-around fertilizer for my orchids. The ...

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  1. #1
    OrchidAddict's Avatar
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    Question What's a good fertilizer?

    Hey all...

    I need a recommendation for a good all-around fertilizer for my orchids. The one I've been using was highly recommended by the high-end nursery I live close to, but upon looking at the label, I now see that 95% of the nitrogen in it comes from Urea, and I have read that Urea is bad for orchids.

    Also, I have recently discovered that some of my orchids need calcium, and this "professional formula" contains none.

    Could anyone direct me to a more well-rounded fertilizer for orchids? They seem to like the high-nitrogen, but I'd prefer it didn't come from Urea (although I don't quite understand the chemistry behind this), and I'd like it to have some other useful stuff like calcium and perhaps seaweed extract...unless seaweed extract is something I need to buy separately.

    Thanks, friends!

  2. #2
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    Jenn I use Michigan State University Fertilizer for well water. Well water can be quite high in Calcium (hard water with lots of mineral content), so if your on muncipal water supply Michigan State University came up with a separate formula for this and R/O water also. I am afraid I don't need to use a calcium supplement to feed my orchids, so I will let others chime in on this who do. In regards to a seaweed extract as you seem to already know others here use it and love the stuff as do their orchids. I use a leading brand of fish extract (Not cooked as fish emulsion is) with seaweed extract included for some of my orchids. The stuff has that fishy smell, though not as strong as emulsion does. I know you can get just the seaweed extract online. The fish fertilizer with seaweed extract is very high in lots of trace elements, though not high in NPK. I know of a good source for the Michigan State University (TYPE) fertilizer in Pennsylvania....................which I've used for years now. PM me if you need more information. AL

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    Hi my favourite fertiliser is Murate of Potash suitalbe for most plants and soil will add depth of colour to your flowers but use sparingly, Epsom salts (magnesium sulphate ) calcium Nitrate & occassionaly seaweed emulsion ( as conditioner only not fertiliser ) onnce a month a hormone treatment 1ml. per ltr. i find best to rotate to get balanced feeding . i have friend who does Not use chemical feeding the receipe is a mixture of weeds from your garden all types ,comfrey , aloe vera . garlic chives ( all in my garden & his ) chop inti small parts or put through mincer hehe. use enough to make , add hand full of cow or chook pellets to 10 ltres water . later use 1 cup of mixture to 5 ltrs water may need to strain if usuing pressure spray kills bugs while feeding naturally worth try ? can treat your whole garden cheers Richard

  4. #4
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    I use Dynamite, which is like Osmacote(sp), a tsp for most plants and I then supplement with a fish/seaweed combo.I was hesitant about using Dynamite but a nursery suggested it, tried it with a few plants first and seemed to work, with a big collection of plants it made things easier and even use it on my vandas, tied up in little balls and hung on the wire above the plant. I think the trick is to find what works for you, good luck.

  5. #5
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    I personally use Dyna-Gro 7-9-5 which seems to be a decent fertilizer, however I would recommend the MSU fertilizer as it is the standard. I also occasionally fert with just epsom salts dissolved in water and every so often with Pro-Tekt, another Dyna-Gro fertilizer that contains silica which is supposed to help the plant retain water and low temperature.

    Now, the reason you do not want Urea based fertilizers is because the Nitrogen that is in Urea is not biologically available to orchids. The way urea fertilizers work is that you water plants, typically in the ground, when the urea hits the ground and the surrounding root zone, bacteria get to work on breaking that urea down into it's elemental parts. It is from this that the Nitrogen can be derived and then used by the plant. Orchids are by and large Epiphytic and as such we grown them in bark or a myriad of other non-soil containing mixes. This eliminates the environment that the bacteria live in that break down the Urea. No bacteria means very little Nitrogen for the plant. So as an orchid grower, you want a source of Nitrogen that doesn't require additional breaking down in order for your plant to use it.

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    Studies by Texas A&M University have shown that orchids utilize nitrogen derived from nitrate better than ammonical nitrogen. Nitrogen from urea is not available to the plants at all until it's broken down by bacteria in the soil. Since orchids don't grow in soil, urea nitrogen is mostly unavailable to the plant. Very few fertilizers have 100% nitrate nitrogen. I like to find fertilizers that get at least half of their nitrogen from nitrate. Don't use a Bloom or Bloom Booster fertilizer as your main fertilizer. Here are some suggestions:

    Orchid Focus Grow (100% nitrate nitrogen but no micro-nutrients. Use a fertilizer with micro-nutrients once a month with Orchid Focus)
    Norman's Optimal Orchid Nutrients (More than 50% nitrate nitrogen and all the micro-nutrients)
    Dyna-Gro Grow 7-9-5 (More than 50% nitrate nitrogen and all the micro-nutrients)
    MSU fertilizers are very good because they contain more calcium and magnesium and less phosphorus but I don't know which brand has the right kind of nitrogen.
    If you want to buy from a local big box store or nursery, Better-Gro Orchid fertilizer gets half it's nitrogen from nitrate.

    (This year I alternated each week between Orchid Focus and Norman's. But I'm always experimenting with new fertilizers)

    I use two supplements on my orchids;
    Maxicrop Liquid seaweed or other brand of seaweed extract (You can mix it with your fertilizer. It's a growth simulator so I only use it from April through Sept.. Not in winter)
    Magical (Magnesium/calcium supplement once or twice a month. If you decide to try this, use it by itself, don't mix it with your fertilizer.)
    Last edited by tucker85; October 11th, 2012 at 10:11 AM.

  7. #7
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    Well, well, looks like you have opened another Pandora's box here hehe. Ok so the general opinion expressed here is avoid urea nitrogen, though I some what agree to this opinion if you fertilize at the roots (foliar fertilization is a very different issue) since you are interested in the chemistry, I will divulge.
    The reason cited here as to why urea is not a good source for orchids at the roots is scientifically wrong. It is not due to its unavailability without the break down by micro-organisms but due to the ammonia toxicity. Urea is an organic compound [CO(NH2)2] as against nitrate (NO3-) and ammonia (NH3) which are inorganic compounds. Urease is an enzyme that breaks down urea into carbon dioxide (CO2) and ammonia (NH3), it is a very robust enzyme produced by many microbes and most of the plants in very high concentrations. So breaking down the urea is not a problem, the problem is what happens next. Ammonia is a highly water soluble gas and it quickly dissolves in acidic water to produce the ammonium ion (NH4+). Actually the degradation of Ammonia can be written in the form of a balanced chemical reaction as follows

    CO(NH2)2 + H2O = CO2 + 2NH3
    NH3 + H2O = NH4(+) + OH(-)

    The Ammonia produced is a very strong reducing agent and hence very caustic, it needs to get protonated that is convert from NH3 to NH4+ . This Ammonium hydroxide is a strong base and is what causes the most damage to the plant. The ammonia produced simply looks for water in its vicinity any where from any tissue and reacts with it, 'burning' the tissue. Soil has more water and other buffering cations and anions that limit the formation of ammonium hydroxide. And thus prevent this burning phenomenon.

    Fertilizing with Urea is like fine art, you need to know the correct balance that will be assimilated quickly without producing too much ammonia to burn your plants. And if you fertilize by foliar application, then urea is the fastest assimilated source of Nitrogen, since it is already in the organic form. Many growers in Thailand use pig urine (high in Urea) as almost the sole source of fertilizer for their plants, and I don't need to tell you how their plants are.

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    And so I stand corrected.

    You learn something new every day!

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    Quote Originally Posted by Halloamey View Post
    Well, well, looks like you have opened another Pandora's box here hehe. Ok so the general opinion expressed here is avoid urea nitrogen, though I some what agree to this opinion if you fertilize at the roots (foliar fertilization is a very different issue) since you are interested in the chemistry, I will divulge.
    The reason cited here as to why urea is not a good source for orchids at the roots is scientifically wrong. It is not due to its unavailability without the break down by micro-organisms but due to the ammonia toxicity. Urea is an organic compound [CO(NH2)2] as against nitrate (NO3-) and ammonia (NH3) which are inorganic compounds. Urease is an enzyme that breaks down urea into carbon dioxide (CO2) and ammonia (NH3), it is a very robust enzyme produced by many microbes and most of the plants in very high concentrations. So breaking down the urea is not a problem, the problem is what happens next. Ammonia is a highly water soluble gas and it quickly dissolves in acidic water to produce the ammonium ion (NH4+). Actually the degradation of Ammonia can be written in the form of a balanced chemical reaction as follows

    CO(NH2)2 + H2O = CO2 + 2NH3
    NH3 + H2O = NH4(+) + OH(-)

    The Ammonia produced is a very strong reducing agent and hence very caustic, it needs to get protonated that is convert from NH3 to NH4+ . This Ammonium hydroxide is a strong base and is what causes the most damage to the plant. The ammonia produced simply looks for water in its vicinity any where from any tissue and reacts with it, 'burning' the tissue. Soil has more water and other buffering cations and anions that limit the formation of ammonium hydroxide. And thus prevent this burning phenomenon.

    Fertilizing with Urea is like fine art, you need to know the correct balance that will be assimilated quickly without producing too much ammonia to burn your plants. And if you fertilize by foliar application, then urea is the fastest assimilated source of Nitrogen, since it is already in the organic form. Many growers in Thailand use pig urine (high in Urea) as almost the sole source of fertilizer for their plants, and I don't need to tell you how their plants are.
    Ahhh...THANK YOU AMEY!! As usual, you are a wealth of knowledge! I had been wondering why manufacturers would even put Urea in their orchid fertilizers in the first place if it was unavailable to the plants. I mean, do they think we're growing them in potting soil or dirt from our yards? But what you're saying makes more sense. It also might help to explain why my vandaceous orchids seem to be doing so well with the fertilizer I've been using. I have them in vases and I let the root systems soak in water with a small amount of fert. during the hottest parts of the day, and the roots are taking off like crazy! Great new top growth too. Perhaps it's because the urea is so diluted because of all the water in the vase, so it doesn't get a chance to burn the roots.

    I have, however, noticed burning on some of my other plants that are in bark. No matter how much I dilute the fertilizer, and even if I water the plant first to let the roots "plump up," I still get root damage. It's very frustrating.

    My phals seem to have taken the worst of it... I can easily see the root damage just by looking into the pot. But the paphs seem to not mind the high-urea fert. Perhaps it's because I keep the media for the paphs much more damp than than the phal media, and I've heard that paphs have developed specially-designed root systems to help them handle the persistently wet media. So I suppose it could be said that Urea is tolerable by vandas in vase culture and by paphs in very moist environments... but anything in bark that likes to dry out between waterings just doesn't seem to do too well with it.

    It seems like the more I learn, the more I realize I still need to learn!! I'll need to keep studying up on this stuff if I want to have an actual orchid nursery someday! Off to do some research....


    Thank you again Amey! You're awesome, and the geek side of me (the geek gene runs dominant in my family) LOVES that you are including the actual chemistry!

  10. #10
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    Wonderful post Amey! Thank you for taking the time to explain this to us!
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