orchid food

[penfold2]

Orchids can't utilize the nitrogen from urea because it requires soil borne microbes to turn it into nitrogen.

I used to believe this too, but it turns out to be a myth. Studies have shown that orchids are capable of directly absorbing urea which is then broken down within leaves and roots by the enzyme urease.

I still use a urea-free formula though, because it's a good formula for other reasons. Also, using at least some nitrogen in the form of nitrate has advantages over using just urea/ammonium. Just wanted to point out that urea will supply orchids with nitrogen.

As for the bloom booster formulas, I see no justification for their use at any time. Just look at the tissue analyses in this article:

East Everglades Orchids Society

Extremely low phosphate levels in comparison to other nutrients.

Among the 3 fertilizers listed, I'd probably use the Jack's Classic all year long. It has a good blend of nitrate and ammoniacal nitrogen, plus calcium, magnesium, and micros.

[King_of_orchid_growing:)]

Originally Posted by penfold2

I used to believe this too, but it turns out to be a myth. Studies have shown that orchids are capable of directly absorbing urea which is then broken down within leaves and roots by the enzyme urease.

I still use a urea-free formula though, because it's a good formula for other reasons. Also, using at least some nitrogen in the form of nitrate has advantages over using just urea/ammonium. Just wanted to point out that urea will supply orchids with nitrogen.

I think I know which article you're referring to, but I don't recall specifically how to search for it...

If I'm not mistaken, the studies were done specifically on Phalaenopsis.

Is it possible to post a link to the article?

[penfold2]

The link should be in my last post, but here it is again.

East Everglades Orchids Society

The data comes from the book The Physiology of Tropical Orchids in Relation to the Industry, which lists similarly low phosphorus levels for Phalaenopsis, Aranda, and Laeliocattleya. It obviously doesn't cover all species of orchids, but I've never seen a study that has shown any plant (orchid or not) that absorbs more P than N or K. So until I do, I'm sticking with low P formulas.

[King_of_orchid_growing:)]

The link you provided mostly covers Magnesium and other macro and micro nutrient supplementation for orchids.

Although it touches very briefly about phosphorous intake in the form of phosphate, which indirectly addresses the issue of how bloom buster formulae are not necessary. However, it doesn't address the use of fertilizers containing urea based nitrogen.

Is there a link that talks about the urea?

[King_of_orchid_growing:)]

Is it this one?

This is only the abstract.

SpringerLink - Plant and Soil, Volume 319, Numbers 1-2

[penfold2]

Ohh, the link I gave was just in reference to the phosphorus issue. The urea issue I read about in the following link (hopefully I can post a link to another forum).

Nitrogen in fertilizers and the truth about Urea - Orchids Forum - GardenWeb

Studies have shown that at least some plants (Phalaenopsis as you showed) are capable of breaking down urea within plant tissues. But urease (the enzyme responsible for breaking down urea) is present in a number of bacteria that are present everywhere. They are floating all around us in the air and water, and this is why aquariums, for example, can break down urea from fish waste without any inoculation. So even if an orchid couldn't break down urea internally, it would still be broken down on the root surface and growing media. The proof for this is that orchids do thrive on a diet of urea only. People were growing healthy orchids before the proliferation of urea-free orchid fertilizers.

That said, I still prefer urea-free fertilizers because I know that all of the nitrogen is immediately available, and I like to eliminate as many variables as possible.

[alsorchids]

I read both articles about what orchid nutrients are needed for optimal growth and health of the plants and was impressed with the research. I appreciate your posts King of orchid growing and Penfold2!

[Royal]

Go to First Rays website. All the info you need is right there.

"Bloom boosters" are not needed. Just a balanced diet at an good concentration. Excess N can actually inhibit blooming, and blooming is better triggered by a reduction in N. See, it's all about the Nitrogen concentration. The other macro and micro nutrients are important, but as long as it's all in there - it's the N ppm that is your focus.

Of course Ray says it better than I do, but that's the gist. I'm no expert, I'm still learning all this too.

[stonedragonfarms]

I'm joining the ranks of non-ticking; I use fish emulsion on all of my plants; 5-1-1 concentration...

[NealW]

I have used the Miracle-Gro 30-10-10 Acid Orchid food on and off for years, it seems to work quite well.
Yes it has urea in it, which is a waste as it is washed throught the mix before it can be utilized, but the is also ammonical nitrogen and that can be utilized immediately. Also the plants really seem to appreciate the acid pH balance. That said, I switch fertilizers regularly, rotating between several different brands/types in order to get a good balance of micro nutrients. Just remember to keep the fertilier concentration on the low side... remember the old saying "fertilize weakly weekly". Some of the more sophisticated growers are recommending about 100-125 ppm dissolved solids in your fertilizer solution, but I don't yet have the equipment necessary to check this.