Fertiliser questions re urea and numbers.

[bil]

OK, I have in front of me three orchid fertilisers.
Growmore premiun orchid feed.
Red 30-10-10 30% urea
Blue 6-30-30 no Urea
Yellow 20-20-20 10% Urea.

I hear a lot of people say shun urea fertilisers because they pass thru the substrate too fast to get broken down and used.

Is that so, and if it is, just what is the point in those fertilisers having the Urea since they are sold as being for orchids?

Next question. I have some fertiliser in granular form, its numbers are

Yellow granular Spain 14-40-5-(13)
%
Total N 14
Ammoniacal 14
Nitrate
Urea

P2O5 40
K2O 5
SO3 13

Boron 0.1
Cu 0.05
Fe 0.1
Mn
Mo 0.01
Zn 0.1

Would that be suitable to use as a bloom boost (to replace the blue feed.)? Or is the phosphate too high and the potash too low?

[Orchid Whisperer]

Hello bil

You will probably hear some some other opinions on this, but there has been research that shows that orchids such as Phalaenopsis can use urea directly - it does not need to be converted to another form first. You can read about this at Phalaenopsis can absorb urea directly through their roots - ResearchGate The abstract, at least, is worth reading, or read the whole thing if you want details.

I am not saying you must use urea, but you can use urea formulations if you like; they will provide nitrogen to you plants efficiently and safely. Urea is very soluble, is directly absorbed by the roots, and is metabolized by the plants. Some people prefer urea-free formulations, and there is nothing wrong with that, but it is not necessary. Use what you feel comfortable with.

Regarding your other questions, maybe this will help. Pretty much all plants will use the main fertilizer components NPK with N being the component that is required the most, P the least, and K similar to nitrogen or slightly lower. Here's another research paper, with this one, experiments were conducted with Dendrobium: Nitrogen, Phosphorus, and Potassium Requirements for Optimizing Growth and Flowering of the Nobile Dendrobium as a Potted Orchid The article recommends N and K concentration of about 100 ppm in the fertilizer solution, and P (middle fertilizer number) of 25 ppm. The experimenters determined that fertilizer N should be reduced at a specific time to improve flowering.

What this means in terms of fertilizer choice is that your N and K should be similar in the formulation during active growth, P can be lower; you don't need high P to get flowering. You can also use a balanced formulation (such as 20-20-20) with no problem. Some people like to reduce N concentration at certain times of the year (like your 6-30-30), or cut back fertilizer in general, to promote better flowering.

I will add that to promote good health, you should regularly provide some supplemental calcium (such as gypsum) and magnesium (such as Epsom salts). There are plenty of other ways to provide Ca and Mg, and those are fine too.

[JMNYC]

Fascinating! I just learned things I did not know!
_________________________________
Edit: I was just, as usual, moved to delve, and came upon this:

Urea confusion - Orchid Forum by The Orchid Source

[Orchid Whisperer]

Originally Posted by JMNYC

Fascinating! I just learned things I did not know!
_________________________________
Edit: I was just, as usual, moved to delve, and came upon this:

Urea confusion - Orchid Forum by The Orchid Source

Well there you go, causing trouble and delving and thinking on your own again!
Thanks for posting that link; I have seen it and similar discussions before, but it is always good to see again.

Just on a 'gut' level, it makes sense for plants that are epiphytes to make use of whatever kind of fertilizer they can get. It would hardly make sense for orchids to evolve such that they were incapable of using urea, especially since urea-producing land animals evolved way before orchids and other angiosperms.

[JMNYC]

Originally Posted by Orchid Whisperer

Well there you go, causing trouble and delving and thinking on your own again!
Thanks for posting that link; I have seen it and similar discussions before, but it is always good to see again.

Just on a 'gut' level, it makes sense for plants that are epiphytes to make use of whatever kind of fertilizer they can get. It would hardly make sense for orchids to evolve such that they were incapable of using urea, especially since urea-producing land animals evolved
way before orchids and other angiosperms.

That.....was ADORABLE! Yes, chasing data 24/7 is my default mode....even Pesto sauce does not seem to mitigate this pathology!

What a fine, relevant, corroborative insight re urea producing animals! Just another example of employing Eyes by Marcel Proust!

[bil]

Originally Posted by Orchid Whisperer

Hello bil

You will probably hear some some other opinions on this, but there has been research that shows that orchids such as Phalaenopsis can use urea directly - it does not need to be converted to another form first. You can read about this at Phalaenopsis can absorb urea directly through their roots - ResearchGate The abstract, at least, is worth reading, or read the whole thing if you want details.

I am not saying you must use urea, but you can use urea formulations if you like; they will provide nitrogen to you plants efficiently and safely. Urea is very soluble, is directly absorbed by the roots, and is metabolized by the plants. Some people prefer urea-free formulations, and there is nothing wrong with that, but it is not necessary. Use what you feel comfortable with.

Regarding your other questions, maybe this will help. Pretty much all plants will use the main fertilizer components NPK with N being the component that is required the most, P the least, and K similar to nitrogen or slightly lower. Here's another research paper, with this one, experiments were conducted with Dendrobium: Nitrogen, Phosphorus, and Potassium Requirements for Optimizing Growth and Flowering of the Nobile Dendrobium as a Potted Orchid The article recommends N and K concentration of about 100 ppm in the fertilizer solution, and P (middle fertilizer number) of 25 ppm. The experimenters determined that fertilizer N should be reduced at a specific time to improve flowering.

What this means in terms of fertilizer choice is that your N and K should be similar in the formulation during active growth, P can be lower; you don't need high P to get flowering. You can also use a balanced formulation (such as 20-20-20) with no problem. Some people like to reduce N concentration at certain times of the year (like your 6-30-30), or cut back fertilizer in general, to promote better flowering.

I will add that to promote good health, you should regularly provide some supplemental calcium (such as gypsum) and magnesium (such as Epsom salts). There are plenty of other ways to provide Ca and Mg, and those are fine too.

Ok, thanks for all that. My huge problem where I am in Spain is that I am sorely limited wrto choice in many things. It is very hard to find any orchid fertilisers ANYWHERE, let alone much in the way of choice. That means ordering from the UK or Europe, and that incurs high postage costs. The Growmore range was recommended to me, but in the UK a single bottle will set me back the best part of 50 POUNDS, and that's before postage. It's cheaper in the States, but then the post ramps it waayyy up. The one good thing here is that as it is an agricultural area with a lot of small growers, fertiliser is relatively easy to get. For example, the mix I posted is one of the more expensive ones, with the high phosphate level making it dear. However, the 25 kilo sack was only 50 euros, which is less than the single jar I saw in the UK. What with funds not being limitless, if I can get my fertiliser like that, it comes out so much cheaper in the long run.
What I need to know, is this.
1. If I stick to the NPK numbers as being the same or similar to the growmore mixes, do I have to worry re how much is ammoniacal, Urea or nitrate?
2. Is there anything in the fertilisers (apart from the NPK) to avoid, or that is a necessity?

I have seen recommendations re magnesium, and I do have some Epsom salts for that very reason. My well water is as hard as nails, so I assume there is little need to add calcium?

Thanks for taking the time to help.

[Orchid Whisperer]

Hi again bil

You do not need a fertilizer that is specifically labeled for "orchids". Any water-soluble fertilizer that is OK for house plants should be fine (possibly water-soluble fertilizer for vegetables, too). If I were to recommend only one fetilizer, I would suggest you look for one that is balanced, like your 20-20-20 in the original e-mail (or you could see if there is one with a low middle number - P). You do not need to worry how much nitrogen is ammoniacal, nitrate, or urea, BUT, remember to use much less than recommended on the label, whether it is called orchid fertilizer, or house plant fertilizer. I suggest 1/8 or 1/4 of the concentration suggested on the label.

I can't think of anything specific to avoid.

It is good to hear you have Epsom salts. You are right, the hard water probably has enough calcium. If it is possible to do so, collecting some rain water (from the roof/down spouts on the house, for example) will allow you to dilute that hard-as-nails water safely. A mix of rain water and your well water should be good, as long as your well water does not contain harmful salts (such as sodium chloride).

[bil]

Originally Posted by Orchid Whisperer

Hi again bil

You do not need a fertilizer that is specifically labeled for "orchids". Any water-soluble fertilizer that is OK for house plants should be fine (possibly water-soluble fertilizer for vegetables, too). If I were to recommend only one fetilizer, I would suggest you look for one that is balanced, like your 20-20-20 in the original e-mail (or you could see if there is one with a low middle number - P). You do not need to worry how much nitrogen is ammoniacal, nitrate, or urea, BUT, remember to use much less than recommended on the label, whether it is called orchid fertilizer, or house plant fertilizer. I suggest 1/8 or 1/4 of the concentration suggested on the label.

I can't think of anything specific to avoid.

It is good to hear you have Epsom salts. You are right, the hard water probably has enough calcium. If it is possible to do so, collecting some rain water (from the roof/down spouts on the house, for example) will allow you to dilute that hard-as-nails water safely. A mix of rain water and your well water should be good, as long as your well water does not contain harmful salts (such as sodium chloride).

Thanks. Yeah a balanced fertiliser does seem the most useful, but what numbers would you suggest for the bloom boosting fertilisers recommended for seasonal use to encourage flowering?

As for numbers, I'm using the 'weakly weekly' regime at the moment, so as the big sacks are dosed in kilos per hectare, I suppose that using the same measure as for the growmore ones will be safe?

Oh yeah, epsom salts. What dose do you suggest please, and how often?

[Orchid Whisperer]

I would skip the "bloom boosters". Everything I have read suggests that these are not really useful. Best is to switch to low nitrogen fertilizer (or just fertilize less) when the plant is not in strong growth mode.

Wow! just big sacks of agricultural fertilizer available? Any online options (similar to Ebay or Amazon)? I have not worked with the fertilizers in the big sacks, but maybe you could try adding small amounts (ranging from 1 cubic centimeter up to 5 cc) to high quality water (such as rain) and see if you can get someone to measure electrical conductivity (EC) for you. It is possible to make a very rough estimate of total parts per million of dissolved solids from EC (roughly, about 150 uS/cm is about 100 parts per million total dissolved solids).

Epsom salts, try 1 teaspoon per gallon (or about 5 cc per 3.8 liters), add about 250 ml of that solution to 4 liters of water when you water once a week.

I hope some of this helps.

[james mickelso]

Your hard as nails water may or may not be hard due to calcium chlorie but instead be hard from iron or manganese. Or a combo of all. That calcium chlorie is not available to your plants. Skp the bloom boosters. It is not the amount of P/K but the ratio of N to P and K at the appropriate time. It's not necessary unless you have a reluctant plant. If you can get 20/20/20 I would use that more than any of the others you mentioned and that is just because a balance is better than switching all the time.