Is it a fact or a widely-held and long time belief that orchids should only be fertilized with fertilizer containing non-urea derived nitrogen? This question has come up on a thread on DG the last couple of days.

Does anyone know if there is a documented study on the subject? Who would be an authority on this question? Is there data available online?

Please check your books and magazine articles, weigh in with opinions, and tell us how you fertilize and what you use. Has anyone conducted their own experiment?

I have a couple of little ones to experiment on. I'll document in pictures using regular Miracle Gro on one, and my usual non-urea orchid fert on the other. I'll have to figure out how to get equal concentration. Not controlled as my orchids are outdoors, or particularly scientific but at least maybe I can set my own mind at rest.

Elaine, lots of reading and some reference books listed in this forum.

http://forums2.gardenweb.com/f...

My brain hurts.

Jim

Thanks, Ken. I had already seen this post. Gotta watch what info you buy into on the internet. The author might be an orchid hobbyist, but he's not remotely qualified to write a dissertation on fertilizer and his references including the German study aren't related to orchid growing. He says "Almost all published studies done on fertilizers and plant nutrients have been done on crop plants. I do think though that much of this is transferable to orchids." Very few crop plants are epiphytes, and the majority of orchids are. So, what he "thinks" in that statement throws cold water on the whole thing, jmho. At the end he says "I realize that the most controversial statement made is probably the ability of plants and I am sure orchids to take up urea directly through their leaves and roots." Hmmm.

According to one of my books, and another article the reason orchids can't use the nitrogen in urea-based fertilizer is because it needs soil-borne bacteria to metabolize it into usable form. So only terrestrial orchids can use it readily since their roots are in soil. I want to know where this information came from, too. Some scientist somewhere must have researched this.

My favorite orchid book, "Orchids to Know and Grow" co-written by two horticulture professors at the University of Florida, both of whom have grown orchids for over 20 years makes no mention whatsoever of using non-urea based fertilizers. It looks to me as if they were careful to avoid the question altogether, in fact. So maybe there really hasn't been a properly documented study about it.

Still reading and searching for any kind of research to confirm the whole urea question. Learning a lot along the way, too. I read 9 different culture sheets from the AOS website, and none of them mention non-urea based fertilizer, either! There were two culture sheets for Cattleyas and Phals for "Novice" orchid growers, and they did say to use "orchid fertilizer". But not all "orchid fertilizer" is non-urea either. The fellow who started this whole discussion read the analysis on the package of Miracle Gro for Orchids 30-10-10 at a Lowe's store today and its formulation included 26% nitrogen from urea and only 4% from ammonia sources.

Trial and error by orchid growers over the years gives a compelling argument for the non-urea side, though. i.e. it's what most people think is right, and what most experienced orchid hobbyists and growers do. I'm not giving up my non-urea fert any time soon. But I do want to know if there's real data to support its use just because that other fellow on DG raised the question. He was using regular Miracle Gro on his orchids, and several people advised him to get some non-urea instead. He asked "Why" and opened this can o' worms . . . ps. Jim, mine too.

Jim, I feel your pain as well. I quit reading at the "tomb" / "tome" part, I thought "tomb" was an apt descriptor for some of those books as you would probably be dead before you finished reading it.

Elaine, your findings are the same as I came up with a few years back and with my limited curiosity on the subject (meaning, I probably wouldn't understand what they were talking about anyway), I didn't pursue the issue any further.

From my favorite orchid book "UNDERSTANDING ORCHIDS" by WILLIAM CULLINA, which has an excellent chapter on 'Fertilization and Nutrition'. I would recommend this book just for this chapter alone. Here are a few lines taken from "UNDERSTANDING ORCHIDS" regarding urea:
"Related to this is the question of urea, which is a synthetic form of organic nitrogen that must be broken down into ammonium by microorganisms around the roots of plants or by the plants themselves before it can be absorbed. Urea is added to soluble fertilizers because the nitrate and ammonium are so soluble that they readily leach out of the pot. Urea is in effect timed-release form of nitrogen that makes ions available over several weeks, so if you apply fertilizer only occasionally, the plants won't be starved of nitrogen. The problem for orchids - especially epiphytic species growing on mounts - is that conditions are not ideal for breaking down urea. In a pot of soil or in the ground, where moisture and temperature are more constant, microorganisms can do their work more efficiently. An organic, water-retentive mix like Pro-Mix would also provide conditions in which urea could be utilized. On a slab of cork, however, conditions are obviously different. Though bacteria are likely to be living in the rhizospere ( the microscopic zone around a root where leachates, mostly sugars, oozing from the root foster colonies of microorganisms that help the root scavenge nutrients), my guess is that most of the urea gets washed away before it can be absorbed. This is obviously wasteful, so check the label to make sure you're getting a low-urea formulation. Some fertilizers sold specifically for orchids state that they are low in urea."

Are you familiar with the FirstRay web site, it contains a plethora of information on orchids and various other things, you could spend days reading through it. Here is a link to his site, drop do down to "Site Map", click on it and take your pick.
http://www.firstrays.com/

Here is a link to an article on Fertilizers on Rays site. I have only read a snip-it of this article so don't know what it contains but there is mention of urea in it.
http://www.firstrays.com/PDF/P...

Good luck in your research!!!

Ken, great research there. I'm just about to the tomb stage from reading tomes, too.

I sent an e-mail to the authors of my orchid book, and got a response from Tom Sheehan, professor emeritus in environmental hort at UF. He sounds like a very nice fellow, and certainly has some creds but he only muddied the waters for me by adding his weight to the "doesn't matter" side of the argument. Here's what he said:
"Elaine, Glad to hear that the orchid bug has bitten you and unfortunately there is no cure and one just continues to expand one’s collection ad- infinitum. Good luck with yours.

With regards to your orchid fertilizer question, I have seen the same information on urea printed in a number of orchid books, yet am not aware of any definitive work in this area. In all my 70+ years of growing orchids I have found that orchid fertilization is the most controversial part of orchid culture with each grower having his own special fertilizer or fertilizer program. Since orchids grow in a wide variety of media, it is difficult to come up with a specific fertilizer for all orchids. I have always been of the opinion that any balanced (NPK) fertilizer used as recommended on the container is usually adequate for the majority of the orchids grown today. As a matter of fact, my present fertilizer program in my greenhouse consists of bi-weekly application of Miracle Grow, using there proportioner. I always irrigate the next day to wash the excess nutrients off of the leaves to prevent green algae from growing on the foliage. Basically, I am folia fertilizing my orchids and they do very well."

So, as far as I can see there are arguments for both sides here, and people who succeed with both kinds of fertilizer. So as you pointed out, curiosity has its bounds and mine is there. Other than carrying out my little experiment with my four little guinea pig orchids, I think I'm going to let it go. Maybe every week or two I'll update progress with pictures of the four victims, looking for signs of new growth or color change. At least I can satisfy myself that for those orchids, in my garden, in summer in Florida it either does or does not make any difference where they get their nitrogen.

Here's my update on the four little orchids I've conducted my amateur comparison on. They've been side by side, in the same light and temperature the whole time. The two on the right have had nothing but approx. 1/4 strength Miracle Gro regular urea-based fertilizer for over 2 months. The other two have had my regular spray formula, 1/4 strength Orchid Plus by Better-Gro non-urea orchid fert. Both sprayers had 3 drops of Superthrive per gallon.

All have been misted daily with mild fert solution and dunked weekly in rainwater, except when I went on vacation. (and for the week it rained non-stop) I mixed the solutions so that the nitrogen components were approximately the same proportions.

Three of the four plants have healthy new spikes coming on. The fourth is green and healthy but is not putting up a spike yet. It is one of the non-urea fertilized plants. The ones fertilized with Miracle Gro are slightly darker green than the others.

So far, it appears the urea-based fertilizer is working as well if not better than the non-urea orchid formula. Further update in October.

Thanks for reporting back! Interesting result! It seems one of the Jungle Eyes is the one without new growth?

Elaine, I await the results! I've often wondered about this myself. That being said, to get a definitive answer, all four plants would have to be the same cross from the same batch to really prove it one way or the other. I feel the same way about the water issue. All of mine are going on city water, which is chunky here, as my rain barrels are almost empty, and no rain in sight until Oct. The explainations sound sensible, but I have orchids that have lived on city water for over 50 years, and do fine. Andy"s Orchids does put "needs good water" on some of their tags, but only a few, and they don't get any more rain than I do. Even if they have huge cisterns, we got less than 9" of rain this last season, so they wouldn't have been filled. I know rain water is not an issue for you, but my point is that these are tough plants, and if you are a purist, you might adhere to these rules. Personally, I believe the strong survive. I just keep trying to find the survivors.

Carol, you're so right, it's not a terribly scientific study I'm conducting. I really just wanted to satisfy my own curiosity. I did have two Lc. Jungle Eyes, (yes, one has no new leaves yet) and two Pot. Slc Fire Fantasy X Blc Toshie Aoki 'Pizazz'. So one of each got the two different ferts. I don't know if they were from the same batch, of course.

Yes, I won't be short of rain water any time soon - wish I could send you some. It's really pouring and blowing like crazy now.

I'll be interested to see if/when I get flowers from any of these little guys. The Pots both have nice vigorous new spikes, as does the one Jungle Eyes that's been getting Miracle Gro. I know Jungle Eyes is a mini and both mine are of a size to bloom, so we'll see soon!

Interim update, sadly I may have lost one of my little guinea pig orchids. The smallest of the two Lc. Jungle Eyes has lost all but two leaves to the black plague. Here's hoping it will survive.

The Experiment will continue with the two Pot.'s though. All three others are growing nicely. The one that is ailing is one that was getting non-urea fert.

I am sorry about the black-rot! This year I am really glad to get the Cattleyas inside, I am afraid I never know where black rot strikes next.

Update on my fert comparision test.

Plant on the left has been getting Miracle Gro, and the one on the right, non-urea orchid formula fertilizer. I don't think I'm seeing much difference in the two. Leaves are the same size and same color. Each plant put on new leaves during the summer, and each has a new pb coming along now.

I too have used non-urea on one group of orchids, different varieties and different species and compared that with urea-fertilizer on another group of similar species/varieties. I see no difference. All mine are growing in pots though - none are mounted. Not scientific but just (practical) observation. Ken

If you're using a quality organic or biodynamic fertilizer, and all your drainage, watering and lighting are all on point, you'll have no problems whatsoever...

Just to add to the above comment, I have been experimenting with a few different fertilisers and find that the organic ones (Powerfeed in particular), whilst generally producing good growth, result in the media (i.e. bark, etc.) breaking down very quickly.

Good grief, this thread dates to 2012!

Interesting Joshua, do you think it is the microbes in the organic feed that are composting the bark?

I am not sure, Alice. I haven't really looked into the mechanism behind it yet, but that is an interesting hypothesis.