How Do You Calculate Nutrient Mixtures?

It's all about understanding ratios and nutrient ppm levels in plants. Go outside those ratios and expect the plant to react negatively. Even then we can only guess since ratios are based on tissue samples. It would be assumed that we are controlling those ppm levels through the nutes, but does 200 ppm of K in nutrient form equate to 200 ppm of K in the tissue sample?
Potassium, Ca and Mg appear to be needed in larger quantities in comparison to other floriculture species. Increasing the levels of K, contrary to the Mulder's Chart, decreases the availability of Ca and/or Mg. Provide K, Ca and Mg in a 4:winkyface:1 ratio avoids antagonisms. The image below shows how increasing K effects the uptake of Ca and Mg.

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Poinsettias need around 200 ppm K to 100 ppm Ca to 50 ppm Mg and since cannabis is similar in that it's a short-day plant it's a good rule to follow.

So now you know that part. The next is understanding how much P a plant needs. A graduate student, Josh Henry, worked on optimizing P fertilization rates for his master’s degree thesis at NCSU. Plants require a baseline level of P to grow adequately. For a continuous fertilization program for plants grown in a soilless substrate, the target concentration is between 8 ppm and 15 ppm of P. Providing levels below that will result in less plant growth, while concentrations above that level provide little benefit.
Since there really is no data on P needs for cannabis increasing those levels from 15 ppm to 25 ppm would be an acceptable range. Higher than that and you risk antagonisms or stimulations. North Carolina State University has begun an experiment looking into optimal P rates supplied at a constant level throughout the cannabis crop cycle and most likely will refine those recommendations in the near future.
The image below shows the response of Alternanthera to increasing concentrations of P from 0, 5, 10, 20 and 40 ppm (left to right).
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You can see the growth slowed after 10 ppm and basically stopped after 20 ppm. Phosphorus is also the primary contributor to plant stretch. Too much P will lead to excessive internode elongation and tall plants. That’s why it’s important to limit excessive P in grow applications. We often hear about growers wanting to add bloom enhancers and yet the plants don't want it and ultimately it leads to deficiencies because of overuse. The next image shows the nutrients that are from a tissue sample of a plant. Again notice the percentages and acceptable ranges.

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You can use the following ratios as a guide to growing cannabis:
10 parts Nitrogen
1 to 2 parts Phosphorus
10 parts Potassium
5 parts Calcium
2 to 3 parts Magnesium
1 to 3 parts Sulfur
The micronutrients are important and most can be found in tap water(get a water report) but if you don't use it then of course you need to add those which most ferts carry enough of anyhow.

The nitrogen should be mainly in the nitrate form as it provides more compact and controlled growth. More extensive leaf and stem growth occurs with ammoniacal and urea nitrogen. In general, to avoid excessive stretching and oversized leaves, more than 60 percent of the nitrogen provided to plants should be in the nitrate form. Ideally 70 to 80 percent as this will provide a moderate growth response and avoid overly large cannabis plants.

I'm sure I bored many here but there's more that is readily available online to look up. Is it a science to figure it all out? Sure it is and that's why people spend years understanding it all. But if you try and follow the basics you'll do fine. Hopefully that's enough to get you on your way. :goodluck:
Pretty cool stuff actually. I'm sure there's a ton of stuff on-line if you know how to find it. Sometimes takes me days or weeks to find things because I'm not real good on a computer.
I don't think I'd find what I'm looking for typing in "How to mix nutrients for cannabis". I guess I suck at finding the correct wording to enter for a search.
 
You can use the following ratios as a guide to growing cannabis:
10 parts Nitrogen
1 to 2 parts Phosphorus
10 parts Potassium
5 parts Calcium
2 to 3 parts Magnesium
1 to 3 parts Sulfur
Wouldn't the plants needs change in flower ? I've always heard a plant needs less N & more K & S during flower.
Not sure why it would need less N; but do understand why increasing the others will help bring out Terps & Increase bud size. But ratios have to be in the ball park to prevent toxicities or lock outs. Problem is they didn't put any N in Sweet Candy or Bud Explosion so kind of hard to get the right ratios without adding some form of N.
 
Wouldn't the plants needs change in flower ? I've always heard a plant needs less N & more K & S during flower.
Well that to me is a myth... at least the N part. I've been using megacrop for quite some time now and there is no way for me to reduce the N. My plants leaves don't snap off whenever I touch them which could be a sign of N tox. You can overfeed any plant with too much N but there's nothing that says the plant needs to have less N during flower, or nothing that I have come across anyhow.
 
Problem is they didn't put any N in Sweet Candy or Bud Explosion so kind of hard to get the right ratios without adding some form of N.
Personally I believe those are for sales purposes only. I keep saying why add more P when clearly science shows that the plant uses very little of it. Looking at Shed's image above the plant increases K uptake during flower, but have you ever seen a K def that was due to a lack of nutrients and not a lockout when using megacrop alone? Logically it would appear there is plenty of K already in it.

Right now I'm day 12 of 12/12 and my plants are being fed 4.5g of megacrop v1 only. The elemental calculator found on the GLN website states that at 4.5g/gal I have the following ppm levels of nutrients. Notice the K level at 179ppm.

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This next image shows what happens when I go to 6g/gal. The K has now increased to 238 ppm.

1599784106577.png


If you recall earlier cannabis likes 200 ppm of K. Why add the boosters again? Clearly we are going to be overfeeding and again demonstrates the lack of needing bloom boosters.

The calculator I'm assuming is for their latest version so my numbers will be lower than those shown.
 
Good Info I'm getting here. It all helps in some way to better understand things. It's still a little confusing; but more than likely because I'm not familiar with most of this yet.
I guess it's mostly a K thing I'm concerned with. Mostly because when I use MC without a K booster I get very little frost on my buds. The difference was night & day when I added the Terpinator last grow. Frostiest buds I ever got. Because of this, it makes me feel like MC needs a better Bloom nute in it.
I need to do a comparison grow from clones to see what happens when I feed 1 plant MC only & 1 plant MC & PK Boosters. I do not believe it was the strain that caused it to form more crystals. I grew this strain once before & it didn't frost up like this & the weed was nowhere close to as good as this time when I added Terpinator. However, I was using AN nutes the 1st time I grew it. But it was a full line up of about 10 AN products.
MC has increased my yields quite a bit which is a good thing. I actually got my strongest weed when using GH nutes; but the yields were smaller.
Speaking of weed I hope my other 3 plants finish in the next 4 weeks or so. Down to an oz. of stash. Brother in law died last week from a surgery that went wrong. My weed went fast helping out family members cope with the loss. That's OK though as it was done for a cause & not for profit. My father in law will most likely pass this year too as he only has 12% mental capacity & can barely breathe. Need to have my next crop ready for it .
 
I'm most likely going to be working in a Cannabis Grow Facility after the 1st of the year. The place is under construction now & I've been in talks with the owners. They've pretty much said I have a job once it opens if I'm still interested.
I'm pretty sure things are done differently in a grow facility then we do things at home.
Hey. Welcome to the club Buds.

I went to the legal commercial side about a year ago. And, man, it IS different.
Like any job, it really depends on how much freedom your 'boss' allows you.
When I first started it was "We have a system. Your job is to simply execute the system. Do not deviate without an ok from us." The results didn't work out well with their 'system.' It was ok, but not good.
They cut way too early, used too much of the wrong ferts at the wrong time, and had the wrong genetics for their goals.
After two turns there was a meeting. "If the weight doesn't go up, we'll have to replace you."
Says me, "Woa. Wait a fucking minute. This is YOUR system. If the weights are not good enough for you, replace yourself. It's your fault. You said yourself that my job was to follow your recipe. If the skipper of the ship says to steer into those rocks, what does the helmsman do? He steers and puts on a life vest. This is your ship and where it goes is your responsibility."

Blank looks. Hadn't thought of that before.

"I don't mind accepting the responsibility for these things, but in return I need the power to make some changes. Changes in staff are not needed - changes in procedure are. Give me one full turn and if I don't get at least 2.5 lbs per 1000 watt light, I will resign. But, get out of my way and let me grow weed the right way instead of your way. Deal?"

Every employer is different, every employee is different. Like any job where you have supervisory responsibility, you can be sabotaged by upper management.
Don't let 'em.
It's better to quit than to get tagged with the reputation of not knowing how to grow; and if you are associated with crap product for too long, the stink wears off on to you.

** I know this is not really what you were asking ... but I thought I'd give you my perspective on making the move, and welcome you to a very small club.
 
Hey. Welcome to the club Buds.

I went to the legal commercial side about a year ago. And, man, it IS different.
Like any job, it really depends on how much freedom your 'boss' allows you.
When I first started it was "We have a system. Your job is to simply execute the system. Do not deviate without an ok from us." The results didn't work out well with their 'system.' It was ok, but not good.
They cut way too early, used too much of the wrong ferts at the wrong time, and had the wrong genetics for their goals.
After two turns there was a meeting. "If the weight doesn't go up, we'll have to replace you."
Says me, "Woa. Wait a fucking minute. This is YOUR system. If the weights are not good enough for you, replace yourself. It's your fault. You said yourself that my job was to follow your recipe. If the skipper of the ship says to steer into those rocks, what does the helmsman do? He steers and puts on a life vest. This is your ship and where it goes is your responsibility."

Blank looks. Hadn't thought of that before.

"I don't mind accepting the responsibility for these things, but in return I need the power to make some changes. Changes in staff are not needed - changes in procedure are. Give me one full turn and if I don't get at least 2.5 lbs per 1000 watt light, I will resign. But, get out of my way and let me grow weed the right way instead of your way. Deal?"

Every employer is different, every employee is different. Like any job where you have supervisory responsibility, you can be sabotaged by upper management.
Don't let 'em.
It's better to quit than to get tagged with the reputation of not knowing how to grow; and if you are associated with crap product for too long, the stink wears off on to you.

** I know this is not really what you were asking ... but I thought I'd give you my perspective on making the move, and welcome you to a very small club.
Good to know. I figured they'd be more concerned with quantity over quality & that part does suck.
 
Good to know. I figured they'd be more concerned with quantity over quality & that part does suck.
The hardest part of my job is trying to explain something that they have never experienced.
My bosses have never smoked.
If they did; they didn't "like it".
*Sigh*

I have a four year degree in Economics, so I speak their language but I try to explain the 'quality' part to someone who has no clue. Try explaining the taste of "sweet" to someone who has no taste buds.

In my situation, if what I need is a 55 gal drum of CalMag, if I get questioned about why I need it, I have to frame the answer in terms of money. Not plant health, or purple stems, or any of that chit.
I would answer something like, "Improper management of magnesium levels will almost certainly cost well over 25% in yield. This is not optional."
See the difference?

You are about to get into the BUSINESS of marijuana.

Simple rule: Make your bosses more than you cost them.
Simple rule 2: If you make your bosses a lot of money, you should cost them a lot of money.
 
I want to chime in after reading this looking for info on Megacrop 2 part I just started using. I am flabbergasted how you have four years growing exp. mentored by a pHd and the knowledge you have.
Nitrogen is kept at adequate levels, is fast acting and potassium has to be replenished due to biostimulants and in heavy flowering. Growing high brix medicine requires a focus on the plant carbohydrate metabolism where there is efficient uptake of minerals in ionic form and chemical reactions. Plant exudates interact with larger molecules and organic biostimulants to induce physiological effects on the plant. Requires a basic understanding of ionic forms and flow for balanced growth of roots and stored sugars.
 
I want to chime in after reading this looking for info on Megacrop 2 part I just started using. I am flabbergasted how you have four years growing exp. mentored by a pHd and the knowledge you have.
Nitrogen is kept at adequate levels, is fast acting and potassium has to be replenished due to biostimulants and in heavy flowering. Growing high brix medicine requires a focus on the plant carbohydrate metabolism where there is efficient uptake of minerals in ionic form and chemical reactions. Plant exudates interact with larger molecules and organic biostimulants to induce physiological effects on the plant. Requires a basic understanding of ionic forms and flow for balanced growth of roots and stored sugars.
My point is more about the K ratio in flower. Since humidity will be lower and plant is drinking lots you need more K to replinish it catalysing sugars and maintain/not overdo N.
 
mentored by a pHd

Who is it, and what (field) is their doctorate in?

Nitrogen is kept at adequate levels

Do you suppose he should keep all the other elements that the plant needs at adequate levels, lol, or would random amounts be fine? I'm asking because you chose to single out nitrogen.
 
Who is it, and what (field) is their doctorate in?



Do you suppose he should keep all the other elements that the plant needs at adequate levels, lol, or would random amounts be fine? I'm asking because you chose to single out nitrogen.
Reading through the thread, the discussion about N and K. And the pertinance to the original post.
 
Who is it, and what (field) is their doctorate in?
I would like to point out that being flabbergasted is not on Dale Carnegie’s list of ways to influence people. I mean, if you are trying to get folks to think you are correct. If not, carry on!
No I'm discussing what I think is correct, I'm putting it on heavy to poke the pHds. I'm totally not trying to influence in any way other than the good way of doing things. That's how I learned a lot sometimes by reading through the comments that discuss commen sense bigger ideas helps expand learning.
 
Seems @Rheaun is a ”high brix” grower, and there is nothing wrong with that, but the OP asked about determining ppm and the math behind it. He may be going to work for a commercial operation that is highly unlikely to care about brix measurements which are not required to grow good medicine, even great medicine gets produced without knowing anything about brix.

The same can be said about concrete (my specialty). There are many who do great concrete work without ever having a clue to the chemistry involved, they just need to know the basics :)

Brix might concerning me if I was growing award winning giant pumpkins, but although I am growing giant pumpkins, it’s not for awards, it was for the fun of growing :)
 
My point is more about the K ratio in flower. Since humidity will be lower and plant is drinking lots you need more K to replinish it catalysing sugars and maintain/not overdo N.
I may have not said it correctly; but you just said exactly what I was thinking at the time. I did not mean to decrease "N".
Just to increase K.
 
I did ask about NPK ratios in the form of ppm for each N - P - K. For instance how to determine what % of N, what % of P & what % of K should be good for flower. The problem I have is the flower boosters only have K or P & K. So how do you balance out the N so the percentages / ratios are correct. Not sure what increases N. Eggshells, Coffee Grounds, etc. or is there a nute to add just N ?
I'm not good at the science stuff. Hated Science ! Should have paid attention in school. But I'm trying to learn it now at 60 years old.
 
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