Fertilizer for Phal

[labyrinth1959]

I have three different fertilizers for my Phals because I thought it wouldn't hurt to have a variety. I bought them after looking at the differences in the NPK content and didn't pay much attention to anything else, after all they were branded for orchid use, right? They are listed as follows:
1. 11-35-15 - no urea
2. 20-14-13 - no urea
3. 30-10-10 - 27% urea
My questions:
1. Is one of these a better choice than the others?
2. Should they all be used but in different situations?
3. Should the one with urea not be used at all because the other two seem to make a point of stating urea free?

All responses are greatly appreciated. Thanks!

[bil]

Fertiliser is mostly polish. NOT the major item in healthy plants.
If you go onto here, there is a lot of interesting info on low potassium fertiliser.

https://firstrays.com/free-information/

I have used this fertiliser at very low levels, and had very good results with it. Its composition is based on what you are likely to find running down a tree trunk.

If I couldn't get that I would go for 20.20.20 or the 30.10.10

I do't think it matters much about urea or not but others may have views on that.

Oh yeah, I use it at very low levels, about 25ppm nitrogen (there's a calculator on that site) in RO water at every watering.

[Orchid Whisperer]

Urea vs. urea-free makes no difference. At one time the belief was that urea would be harmful to orchid roots. This was originally because a long time ago, urea fertilizer (made using primitive manufacturing processes) contained harmful amounts of a chemical impurity called biuret. With modern manufacturing processes, this is no longer a concern. Later, it was believed that urea had to be 'mineralized' by microbial action into either nitrate nitrogen or ammonia nitrogen before it could be used. Recently, research has proven that orchids can absorb and use urea directly (see https://www.researchgate.net/publica...gh_their_roots). Like many other plants, orchids contain an enzyme, urease, that helps them metabolize urea. The 'urea-free' thing is a carry-over, as there are many growers still concerned about this, so some fertilizer manufacturers prefer to cater to the demand for urea-free fertilizer. I use both urea and urea-free formulations.

If you have mature plants, the lower nitrogen 11-35-15 formulation may be a good choice. Too much nitrogen may reduce the quality of blooming (the plant uses the extra nitrogen to build more leave and stems instead of flowers). I use a formulation similar to this for my mature plants. They grow and bloom well. I provide supplemental calcium (as gypsum) and magnesium (as Epsom salts), and also provide other micronutrients with monthly supplemental applications of kelp extract.

If you are growing young orchids and are trying to make them bigger, the higher nitrogen 30-10-10 formulation may be a good choice.

Really, you can use any fertilizer as long as you remember that orchids generally grow better with lower fertilizer strength. When orchids are actively growing, I try to provide fertilizer once or twice a month at 1/4 of the strength of whatever the manufacturer recommends. This seems to be more than adequate to keep my plants happy.

[flowerpower]

As far as Phals go, I have never found they seem to care what you use as long as they get a little bit here and there. When they are in the mood to bloom for you they can be very determined about it (speaking as someone who has broken more than one flower spike and had them branch out from another node). When they don't want to bloom, they will take their sweet time to give you a spike no matter what you feed them (usually they are concentrating on roots or leaves).

As far as nitrogen goes, I'd rather have a fertiliser with lots of other minerals in it than high nitrogen. I would not use the high nitrogen fertiliser all the time. Perhaps use it when you see the Phals are putting out a new leaf but when you see the flower spikes initiating, switch to the balanced one? That is what I would do.

[Ray]

I am the believer in "very little, all the time," as that mimics what the plants see in nature, but if you look at what they get, it's almost all nitrogen.

I, too, used to warn against "high nitrogen" fertilizers, as nitrogen can stifle blooming. However, I have since come to understand that it's not the formula that controls that, it's the mass of nitrogen applied, which is a combination of formula, concentration, and frequency of application.

For example, Mir-Acid was my standard "bad guy" at 30-10-10, but I now use K-Lite at 12-1-1, making it 4 times more "high nitrogen" by ratio. I only use it at about 25 ppm N though, and it really gets flooded at each watering.

And I since I mentioned that, if you want the best, fastest-growing plants, you need to use a potting medium that drains rapidly, and water frequently and heavily. If you look and the processes and chemistry used in growth of a plant, in order for a plant to gain 1 pound in mass, it must take up and process about 25 gallons of water, yet only about a teaspoon of fertilizer elements.