First Post... and Orchidgain dilution rates?

[CMroz]

Update** Here's a link to a little calculator I made based on Ray's posts below: Fertilizer Calculator
Ray also added a much more professional version to his site, so check it out!**

Hello everyone!
As the title states this is my first post, although I have used this forum as a research/advice tool for years. So first of all - thank you!

A little background:
I've been growing orchids for about 5 years, but only with a very small collection of 4 orchids. I repot every year and have even had my Phals and Cats rebloom a few times (but certainly not every year). I've always been very interested in orchids in general, but it has been a more passive interest. I've been tending my vegetable garden for about 10 years so that has been my primary focus.

Two things happened recently that have turned my interest into a burgeoning obsession. I had one of my Cattleyas, which I have been growing since it was very young, bloom for the first time. I was fascinated, as I'm sure many of you know the feeling. And I made the mistake of attending a local Orchid Society auction... where I effectively double by collection with 3 Paphs and a Bratonia, all great deals (one phal with a very complex label... a question for another day). Since then I have been falling in deep and renewing my interest in growing these amazing plants properly. I've shifted over to a semi hydro potting for my new orchids - which came with very few roots. I have no real fertilizer schedule yet, but would occasionally feed with some generic orchid water soluble I had - which I know realize is a bad fertilizer because it contains urea. Anyway I have researched like crazy on the boards here and First Rays, and of course realized it's a very complex topic. This leads me to my fertilizer question.

I inherited a bag of Orchid fertilizer called Orchidgain from BGI fertilizers. I originally dismissed it and looked at my full range of options. I settled on the MSU fert from RePotMe. For the heck of it I compared labels and was surprised to find they are incredibly similar. Nearly the same NPK ratios, provides calcium, and similar micro-nutrients. What's not the same is the price (Orchidgain is quite a bit cheaper) and the suggested dilution per gallon of water. I'm used to seeing dilution rates around 1/2 to 2 teaspoons per gallon. Orchidgain suggests 9-1/3 tablespoons! Using First Rays calculators I get something closer to 1 teaspoon... so this seems like a decent fertilizer that is half the cost of the MSU fert, but I wanted to see what everyone here thought. Should I just try it out for a while with 3/4 teaspoon dilution every week and see what happens?

Here's a picture of the back of the bag.

P.S. I've never heard of this fertilizer in the past, and there seems to be no mention of it on the board - so I am spectacle. But after some research I found out that the company is based in Florida and seems like a legit business.

Thanks again!

[estación seca]

By law the numbers on the bag are supposed to match what is inside. The numbers do, indeed seem to be similar to MSU. The amount they say to use is extremely high.

I think there must be a proofreading error on the label. Notice that on the very top line of the label, they misspell their own product name. I don't think the dilutions they give are correct.

I agree with Ray's teaching that PPM nitrogen is a good way to calculate fertilizer concentrations. If you fertilize at every watering, aim for 20-50 ppm nitrogen. Less often, increase that number. Use the calculator on the First Ray's Web site.

I fertilize my plants in S/H at every watering. I use 1/8 teaspoon of MSU powder per gallon of water. (0.625ml of powder per 3.78 liters of water.)

[CMroz]

Thanks for your advice estación!
I think what I will try to do is create a concentrated mix with the fertilizer as Ray suggests for consistency.

I'm not terrible with math, but try as I might, I can't really figure out what formula they are using on the "dealing with fertilizer powders" (sorry, I'm not allowed to link to it) and how it ends up being 1/6th strength. Do you have any experience with that? I must be missing a number or conversion factor or something.

[bil]

Google 'First Rays nitrogen calculator' For general orchids, I use 20-25ppm N
So if you want that, feed that number in with the % N in the fertiliser and get the figure out at the bottom for what you need per litre. It really isn't much.

[estación seca]

Originally Posted by CMroz

...I can't really figure out what formula they are using on the "dealing with fertilizer powders" (sorry, I'm not allowed to link to it) and how it ends up being 1/6th strength....

I don't know which site you mean. First Rays? Orchidgain?

First, I suggest you stop thinking in fractional strengths or dilutions. It is confusing for most people. Different fertilizers have different formulas, so you can't compare a fractional dilution of one kind against another. Think in terms of parts per million of nitrogen in your solution. Plants need so little of other nutrients that paying attention to the nitrogen is all a hobbyist needs to do.

The fertilizer calculator on the First Rays site shows how much fertilizer powder to use to get a desired parts per million of nitrogen in the solution. You must input the N number from the fertilizer label, and the desired parts per million of nitrogen in your final concentration. The answer is given in volume of powder per volume of water, for both English and SI units.

To make concentrations using volumetric measurements (I will use US English measures. The principle doesn't depend on units chosen):
Decide how much fertilizer powder you want to use in your final dilution for watering plants. For example, some people might want to use 1/4 teaspoon of their fertilizer powder per gallon of water on their orchids.

Decide the final volume of liquid concentrate you want to use. For example, some people might want to put 1 teaspoon of the liquid concentrate they mix up into 1 gallon of water to get the final fertilizer concentration they want.

This means you will want 1 teaspoon of your liquid concentration to contain 1/4 teaspoon of powdered fertilizer.

If you want to use an entire new container of fertilizer powder, you must figure out how much powder it contains. Measure it out and count.

3 teaspoons = 1 Tablespoon
16 Tablespoons = 1 cup
4 cups = 1 quart

If you wish your liquid concentrate to contain 1/4 teaspoon of fertilizer powder per teaspoon of liquid concentrate, that means that means you will have a final volume of four times the fertilizer powder volume. If you have 4 cups of powder you will eventually dilute that into a final amount of 16 cups using water.

But the volume of liquid may change when you dissolve fertilizer in it. So you must put your powder into a smaller volume of water, stir until dissolved, and top it up with fresh water to yield the desired amount.

Ray mentions it is better to weigh powders when mixing dilutions. Scales with small gradations are not commonly used in US kitchens when cooking, and most people don't have such a scale. So I will not go into this here.

[Roberta]

I am inclined to keep it simple... Whatever the bottle says to use, I use 1/4 to 1/2 of that amount. So if the instructions say "1 tsp per gallon" I use 1/4 - 1/2 tsp per gallon. I figure that the manufacturer is trying to sell fertilizer. Orchids don't eat much, because they grow slowly.

[CMroz]

Thanks Roberta - I definitely want to keep it simple!

And thanks estación seca for the great info. I was referring to this page (firstrays.com/free-information/feeding-and-watering/fertilizer-information/dealing-with-fertilizer-powders/) from First Rays. It's probably over complicating it, and not necessary, but the logic of creating a consistent liquid mix makes a lot of sense to me - but I think you covered that in your post. I was planning on weighing it all out according Ray's formula but I couldn't quite follow it (I use a pretty accurate kitchen scale for baking bread, so I'm comfortable with that).

Anyway, this is a great place for me to start learning about how complicated - or not - you can make feeding your orchids.

Thanks again.

[Roberta]

Originally Posted by CMroz

Anyway, this is a great place for me to start learning about how complicated - or not - you can make feeding your orchids.

Thanks again.

Another reason to not over-think fertilizing... fertilizer is not a big factor in orchid-growing. You can't make a sick orchid better with fertilizer... if you get the rest of the culture right (temperature, light, air movement, watering) then fertilizer can improve plant growth. Yes, orchids need it, but not much - they grow slowly. Think of it as vitamins, not "food"... green plants make their own food, the "vitamins" add just that little bit more.

[Ray]

Ppm N is a solid number. "1/4 strength" isn't. If you used 1/4 of your 9-1/3 tablespoons, you'd still be poisoning your plants.

Making a concentrate is actually quite simple.

1) Decide the concentration (ppm N) you want to apply. For example, let's use 100 ppm N.

2) Determine how much of that powder fertilizer you need for that concentration. For example, for a 13%N formula, 100 ppm N requires 2.9g/gal., or to guesstimate it divide 8 by the %N for the level teaspoons/gal. (8/13=0.62 or almost 5/8 tsp/gal).

3) Determine a convenient measure for further dilution. Let's say you have a spare shot glass - 1.5 ounces - that'll you'll use, adding that amount of your concentrate per gallon of water.

So, for that 100 ppm N final solution, you'll need that 2.9 grams or 5/8 teaspoon of powder to be contained in that shot glass of concentrate.

A gallon is 128 ounces, or 128/1.5= 85 shot glasses (it's really 85-1/3, but rounding is unimportant at this stage), so, your gallon of concentrate will need 85 x 2.9g = 246.5g, or 85 x 5/8 tsp = 53 teaspoons (1 cup plus 5 teaspoons) of powder.

[CMroz]

Thank you so much Ray! I've referenced your site so many times in the past so I appreciate all the great info you have provided.

Your post makes perfect sense, and this is exactly what I was looking for. I'm a stickler for consistency so I definitely prefer the weight method. I'll admit I still don't know the exact conversion factor/formula used to derive the "2.9g/gal" requirement - but I have no problem taking your word for it and mixing up a concentrated batch! Thanks again!