Chem. Orchid fertilizer recipe wanted

[Symbiot]

Hi

I grow aquatic plants... lots of them.. and I mix my own fertilizer from KNO3, KH2PO4, MGSO4, K2SO4 & Trace Elements..

I also grow Orchids... and have been using commercial fertilizers for a while..

But since I have all the ingredients to mix my own orchid fertilizer I thought... well .. Why shouldn't I..

But I've been struggling finding recipes for orchid fertilizer..
well.. apart from 20-20-20 etc..
But I work in PPM or mg/l... but haven't been able to do the proper translation from 20-20-20 (example) to ppm or mg/l..

Does anyone out there have a recipe or a way to translate the numbers on commercial bottles to something I can weigh/measure?

What's YOUR fertilizer recipe?

I grow a wide variety of orchids from Drac's to phal's...

Hoping for some help & guidance..

[DavidCampen]

Well, while doing the calculations doesn't require any more than simple arithmetic is does get a bit involved and arcane.

For starters, if you are going to make your own orchid nutrients, you are going to need sources of soluble calcium and magnesium.

Greenhouse grade calcium nitrate, also called calcium ammonium nitrate (CAM) is a good source of calcium and nitrogen. Here is one brand:
YaraLiva

Greenhouse grade magnesium nitrate is a good source of magnesium and nitrogen. here is one brand:
Magnisal - Water Soluble Fertilizer - Haifa Fertilizers

There are more complications to come but first lets calculate the NPK,Ca,Mg of a formulation of the 2 materials.

So CAM has an NPK value of 15.5-0-0 and 19% calcium.

Magnisal brand magnesium nitrate has an NPK of 11-0-0 and 9.6% magnesium.

It is a bit hard to show the calculatons here since these posts don't format data tables well so to help a bit I will write the compostion of CAM as 15.5-0-0-19-0 (N-P-K-Ca-Mg) and Magnisal as 11-0-0-0-9.6.

So if you wanted to calculate the N-P-K-Ca-Mg of a 3:2 mixture of CAM:Magnisal you would start:
3 parts X 15.5-0-19-0=46.5-0-0-57
2 parts X 11-0-0-0-9.6= 22.0-0-0-19.2
--------------------------------
5 parts 68.5-0-0-57-19.2

68.5-0-0-57-19.2 divided by 5 = 13.7-0-0-11.4-3.8

So, 3 parts CAM plus 2 parts Magnisal gives you a fertilizer composition of 13.7-0-0-11.4-3.8 (N-P-K-Ca-Mg)

Next we need to add phosphorous and potassium and then consider the ratio of nitrate to ammonium nitrogen.

[tucker85]

Here's a ppm calculator from First Ray's web-site.

https://www.firstrays.com/fertcalc.htm

[Symbiot]

Hi Guys.

And thanks for your Answers..

David, any chance you can mail me a spreadsheet? or link to one?

What I need is get down to the Grams pr. liter type numbers

[Symbiot]

Basically.. If I want a 20-20-20 fertilizer...
and I want to mix it in water..
and then dose x ml pr. liter of pure water... Then... how to get to the mixing values...

[vanda man]

I have a recipe from a lot of Malaysian orchid growers and I find it quite useful.
Here's how you do it
1)brew some tea one day before fertilizing your plants.
2)Mix the fertilizer into the tea instead of the water.
The tea contains tannic acid which is believed to help with flowering.
If you find better ways please share it with me.Hope this way helps you.

[lepetitmartien]

@Vanda man, there may be other reasons. Tannins have know antiparasitic, antiviral, antibacterial virtues, plus they keep some pests away.

Is it any tea, or green tea only for example?

@Symbiot, a simple rule of thumb is to divide the N number by 5, it'll give you the dilution of the recommended mesure of fertilizer whatever it is into water (in liters). This gives a medium value fine for phal and current orchids. (source: orchidoudingue french forum, in the article sections, written by a biologist who did a thesis on S/H for orchids and cared about the ppm -another article- and fertilizer stuff)

It is to adapt if needed as some orchids genus like more (rarely) and some less, or way less (a half or a fourth of it).

So if you have a fertilizer 20-20-20, and you must use on the label 1g or 5 ml of it, 20/5=4, so it's 1g or 5ml for 4 l (or 8 or 16 liters for low fertilizer species).

I won't enter on the ppm area, I'm sure some people will explain it way better than I can.

[Paul Mc]

Tea?!!! Wow!!! I may use this to rid my plants I just brought in of pests then!

[DavidCampen]

Originally Posted by Symbiot

Hi Guys.

And thanks for your Answers..

David, any chance you can mail me a spreadsheet? or link to one?

What I need is get down to the Grams pr. liter type numbers

I don't have a spreadsheet, I just use pencil and paper or do it in my head.

The N-P-K numbers on a fertilizer label are the weight percentages. The 1st number is the weight percent of nitrogen. So if you take 5 grams of a 20-20-20 fertilizer, 20% of that or 1 gram is nitrogen and if you dissolved that 5 grams of 20-20-20 in 1 liter of water you would have 1 gram of nitrogen in 1 liter (1000 grams) of water so the concentration of nitrogen is 1 part per thousand or 1000 ppm.

The above calculation is a good approximation for relatively dilute solutions but to be completely accurate the calculation should be 1 part nitrogen divided by 1005 parts of solution which is 0.995 parts nitrogen per thousand parts solution which is 995 ppm.

[DavidCampen]

I prepared a batch of fertilizer stock solution last night. If I had mixed it as a dry powder then in that form it would have a composition of:
13-4-8-9Ca-3Mg-1S.
This is much higher in calcium, magnesium and sulfur than commercial formulations so it should eliminate the need for supplemental applications of calcium, magnesium and sulfate.

The formula used is:
60 g Calcium Ammonium Nitrate (15.5-0-0-19Ca)
40 g Magnesium Nitrate (11-0-0-0Ca-9.6Mg)
10 g monoPotassium Phosphate (0-52-34)
10 g Potassium Nitrate (14-0-46)
5 g Ammonium Sulfate (21-0-0 24S)
4 g Potassium Acetate (0-0-50)
2 g Acetic Acid
also minor elements:
120 mg Iron (from Ferric Ammonium Citrate)
100 mg Sodium Chloride
60 mg Copper (from Copper Glycinate)
60 mg Manganese (from Manganese Sulfate)
60 mg Zinc (from Zinc Glycinate)
24 mg Boron (from Boric Acid)
1.8 mg Cobalt (from Cobalt Sulfate)
1.2 mg Molydenum (from Sodium Molybdate)

These were combined with water to total 2 liters of stock solution. This stock solution is being used via a chemical injection pump at about 1 part stock solution to 150 parts water. At this dilution it has a pH of 5.5 and a measured TDS of 250 (as estimated from EC measurement).