Does High Number P Fertilizer really work?

[isurus79]

From what I understand, urea based fertilizer is not useable directly by orchids, but needs to be altered by bacteria present in the media. Once the fert is converted by the bacteria, the orchids can utilize it but it takes longer to make it available to said orchid. One of my local orchid society's best growers uses urea based fertilizer with outstanding results. I personally have never used it.

[james mickelso]

We need to remember that commercial growers and some of the larger scale hobbyists grow in more optimal environmental conditions than we mere mortals and yes they don't have time or manpower to switch fertilizers. They get their results more from their growing conditions than simply what fertilizers they use. And they aren't growing large scale lots of orchids in Michigan, Montana, Oregon, or Nebraska. Or even Texas. Hawaii is optimal for growing orchids due to their stable temps, humidity, and little variation in length of day/night. We small hobbyists sometimes need some tricks of the trade and personal experimentation to get orchids to grow well and flower reliably.

[Orchid Whisperer]

Steve:

Re: urea, yes, orchids can use urea directly, they have an enzyme (urease) that aids in utilizing the urea once it's absorbed. There was a study done by Martin Trepanier, on Phalaenopsis, that confirmed this. The article is easy to find by Google search but if you can't locate it, I can probably send you a link. I personally contacted the author & he indicated that most orchids should be able to do this (many non-orchids also can use urea directly).

Conversion of urea to other nitrogen forms, external to the roots/plant, is not necessary for urea to be utilized. It might happen under certain conditions, but that external bacterial metabolizm seems to be unnecessary.

[isurus79]

Originally Posted by james mickelso

We small hobbyists sometimes need some tricks of the trade and personal experimentation to get orchids to grow well and flower reliably.

Well this is true, but as someone who started growing orchids in Canada, then Arizona, Hawaii and now Texas, I personally have never needed high P fertilizers to get my guys to bloom. And like most commercial growers, most (many?) hobbyists are growing many different genera and giving different fertilizers to each plant during various phases of growth becomes a cumbersome and (IMO) unneccessary endeavor. A good fertilizer all year long seems to work for the hobbyist and commercial grower alike.

Originally Posted by Orchid Whisperer

Steve:

Re: urea, yes, orchids can use urea directly, they have an enzyme (urease) that aids in utilizing the urea once it's absorbed. There was a study done by Martin Trepanier, on Phalaenopsis, that confirmed this. The article is easy to find by Google search but if you can't locate it, I can probably send you a link. I personally contacted the author & he indicated that most orchids should be able to do this (many non-orchids also can use urea directly).

Conversion of urea to other nitrogen forms, external to the roots/plant, is not necessary for urea to be utilized. It might happen under certain conditions, but that external bacterial metabolizm seems to be unnecessary.

Ah, this is good info! Thanks!

[Orchid Whisperer]

Here is a link to the Trepanier article if you are interested:

Publications: Centre de recherche en horticulture[showUid]=1199

[NYCorchidman]

Again, so much hoax out there confusing the #* out of me and many others. lol

I also read online and even in the books that orchids cannot use urea unless it is broken down by microorganisms. Then nearly all the orchid fertilizers I could find at local stores are urea based.
I also read it has to do with the low cost of making urea as compared to the cost of other forms of nitrogen fertilizers.

Then I ran across some articales saying this urea thing that has been spreading all over is untrue.

Maybe this explains why I don't see any difference in my plants whether I use urea based or non-urea based fertilizers.

I wish there was some kind of ultimate fertilizer guide with none of the BS. lol

[ALToronto]

Yes, they all work well - urea-based fertilizers can really drop your pH, though, so if you have very alkaline water, they may be the better choice. I found that less is more - I now fertilize at 20 ppm N (which in some cases is 1/20 of the label amount, and the water is not blue at all), and my plants are doing great.

I use K-Lite (nitrate source) and fish fertilizer (natural ammonia source) fertilizers at this concentration.

[NYCorchidman]

I read about how pH of the water with fertilizer mixed in is much more important as pH determines the availability of elements to the plants.

and different kind of plants prefer different types of nitrogen source, which I am not yet convinced. It could again be the final pH due to different sources of nitrogen used. maybe not.

I looked up NYC water report again, and it really is close to pure water! If anything, my plants might have been underfed, not overfed. lol

I live in a brand new building, so I doubt I have lots of stuff dissolved in the water due to old pipes.
then again, I'm really curious about the pH. It says NYC water pH ranges between 6.7-9.2, which is a huge swing, with an average being 7.2.

I want to get a litmus paper somewhere ( where do I buy this???) or pH meter and find out what my tap water pH is and also the pH of the water with the fertilizer mixed in.

[Orchid Whisperer]

Hi NYCorchidman
pH testing supplies that are "good enough" probably can be obtained from a pool supply or aquarium supply store. A good garden center may have litmus paper, or you can order online.

With any meter, if the meter can't be calibrated to known standards, it is not really worth it. I know some may disagree, and that is their choice, but with conductivity, TDS, and pH, readings on even good meters "drift", and cheapie meters drift even more. A meter that you can calibrate can be corrected for drift, variation in results with temperature, etc.

The litmus paper is a good idea for pH. I have seen pHydrion brand litmus paper on Amazon, one type ranging from 0 to 13 pH (Insta-chek 0-13) and another from 5.5 to 8.0. There are many suppliers selling through Amazon.

If you get curious about TDS or conductivity, your NYC water department probably has a web page and likely keeps all that data updated on the website. As large as NYC is, there are likely to be many water plants, find the plant closest to you, that's probably where your water comes from, use that data.

Edited later by OW I guess I didn't see that you already HAD data from the water department - sorry, my bad. where's a :facepalm: smiley when I need one?

The pH of your water is probably due to pH adjustments the water plant makes to keep pipes from corroding. Although the range you gave is large, they are probably trying to keep pH near 7 (that pH = 9.2 would worry me).

[NYCorchidman]

Thank you for the answer.

I think I will just order litmus papers online. It is cheap but gives me idea of where the pH falls.

I looked around and I just don't want to waste money on pH meters. lol
I read the same thing about the light meters. The readings are often way off, which explains some crazy reading results that I saw recently on someone else's thread. I believe that one was broken. It was more than just off to say the least. lol