Leaf darkening mystery I can't figure out

[plan500]

Nice looking grow.

The darker green plants do look healthier.

Excess nitrogen does cause almost all plant leaves, and not just Marijuana leaves, to turn a dark green but that would be a much darker green, almost looking like a black green in color. Your plants look a long way from excess nitrogen.



Could something else be causing the darkening? I am suggesting that this might be it. When you switch over from the Grow fertilizer to the Bloom fertilizers and add in the Green Sensation plus the P/K Booster you have dropped the Nitrogen. At the same time you have increased the amounts of both Phosphorous and Potassium big time.

The Phosphorous is needed for improved growth at all growing tips and this helps promote the flower bud development. It also helps with photosynthesis. In the long run though it does not seem to be the most important of the macro nutrients.

The Potassium is the number one macro nutrient that is used for overall plant health and growth. In my opinion it is more important than Nitrogen in this regard though the Nitrogen is still needed.

A couple of years ago in a thread about other fertilizers @InTheShed posted this message that went into the amounts or levels of the three macro nutrients that are needed during the growing stage and during the flowering stage.The study done by botanists and horticulture science people is found at the link he included in his msg. There is a bit more to the study than just the bar charts.

https://www.420magazine.com/community/threads/mega-crop-is-it-really-an-all-in-one-fertilizer.499794/#post-5299193

Low levels of both available Nitrogen and Potassiumn can cause a yellow color to start appearing in the leaves. As long as the deficiency does not get severe or last long enough to cause permanent damage to the leaf it can be fixed when the levels of those two increase.

I am figuring that the green is the result of the increased Potassium is aiding the overall plant health and therefore color. Plus, the plant can now better use the available Nitrogen. If it was my grow I would be considering an occasional watering with some type of Nitrogen source, probably something from a liquid fish source since they are easy to mix up and the plants seem to react quickly to nutrients derived from fish and it is hard to overdose with fish.

All this is something to kick around while you are thinking about your experiments.

Thanks for the detailed analysis!

Now that you have confirmed it (and I also got similar answer in another forums) I can conclude that the darkening is a positive change towards healthier plants.

I've looked into the info with regards to NPK uptake charts that you shared. This brings up an important topic that has been very confusing for me along the years. One thing that isn't clear though, is if this uptake is for a specific week of the flowering or some rounded average. In other words is the N uptake in flowering the same in each of the 9 weeks?

To make things specific to my case would you say that my feed schedule is adequate based on your experience and the extent to which you would follow the conclusions from the report?

I don't usually have any yellow leaves, even lower, until late week 7, so I would assume that N is enough.

I have introduced Green Sensation (0-9-10) a bit earlier that recommended and also the addition of P/K is all my idea, thinking they need a lot of PK weeks 6 through 8.

It says on the Green sensation bottle that you should use 1ml/L from week 4 and that you should top up with the basic Alga Bloom food till the desired ppm is reached.

Would you say I should get rig of the P/K and perhaps add 0.5-1ml more from the basic food instead?

Any recommendation here are welcomed as this nutrient line is mostly used in Europe, and I can't seem to find any trustworthy feeding chart or info from journals.

 

[Gee64]

If you are low on calcium then the magnesium in your soil will tighten the soil and choke air off. Air is 78% nitrogen.

When you add cal/mag the calcium addition neutralizes magnesium's charge, and magnesium's grip on the soil relaxes.

It works quick, almost on contact, and air rushes back in with a huge dose of nitrogen.

Quite often the effect is so profound the plant turns much darker and you see some leaf clawing too.

Later in the plants life you will see a direct line of clawed leaves across a level of the plant to remind you of it.

Adding cal/mag directly injects nitrogen from the air into the soil. Thats exactly what it is supposed to do and one of the reasons why you use it.

If it always happens at the same stage of the grow, chances are you are following a grow calendar and adding cal/mag right before each time you see the darkening/clawing.

I did this on purpose a few months back as a demo. See the leaves in the circle all clawed, that was calcium day. I used dolomite water but cal/mag has the same effect. It darkened the entire plant too.

 

[plan500]

If you are low on calcium then the magnesium in your soil will tighten the soil and choke air off. Air is 78% nitrogen.

When you add cal/mag the calcium addition neutralizes magnesium's charge, and magnesium's grip on the soil relaxes.

It works quick, almost on contact, and air rushes back in with a huge dose of nitrogen.

Quite often the effect is so profound the plant turns much darker and you see some leaf clawing too.

Later in the plants life you will see a direct line of clawed leaves across a level of the plant to remind you of it.

Adding cal/mag directly injects nitrogen from the air into the soil. Thats exactly what it is supposed to do and one of the reasons why you use it.

If it always happens at the same stage of the grow, chances are you are following a grow calendar and adding cal/mag right before each time you see the darkening/clawing.

I did this on purpose a few months back as a demo. See the leaves in the circle all clawed, that was calcium day. I used dolomite water but cal/mag has the same effect. It darkened the entire plant too.

This is what Chat GPD says about cannabis drawing nitrgen from air (Nitrogen fixation). Doesn;t this contradict your point?

I do add Cal/Mag throughout the whole growth with each watering. However the amount is minimal, just so I don't get any deficiencies. For weeks 1-9 of flowering this is my schedule:

and in vegging:

And yes I have observed some clawing but I have related it to excess Nitrogen. (still not sure)

Here are a few images where the clawing is visible. It happens with every grow, usually stays in the middle of the plant.

So what do you suggest I do with the CalMag?

 

[bluter]

This is what Chat GPD says about cannabis drawing nitrgen from air (Nitrogen fixation). Doesn;t this contradict your point?

just no. that shit only returns generic junk. grow by it if you wanna live milquetoast.

I do add Cal/Mag throughout the whole growth with each watering.

how much does your nute carry ? what are your using for water ?
you may not need it if you are not on RO. the amounts you are adding don't really mean much.

And yes I have observed some clawing but I have related it to excess Nitrogen. (still not sure)

it's a bit high in N. a lot of nute schedules run that way in veg. they usually build a slight excess in veg to get it all the way through when it hits flower. most schedules pull it back a bit in flower, but the plant will use some all the way through.

Here are a few images where the clawing is visible. It happens with every grow, usually stays in the middle of the plant.

that's where your schedule built the N in veg.

So what do you suggest I do with the CalMag?

you can pull back a little if concerned and run half to 3/4 in veg. otherwise follow the schedule and continue on.

the nute schedule has been built likely based on RO or a low ppm water source. it's impossible to know what the conditions will be like for every grower, so that is how the nute companies set the schedule.

your conditions will not match exactly, there will be some variance, but not a lot. it's up to you to read the plants and adjust as necessary.

 

[Gee64]

This is what Chat GPD says about cannabis drawing nitrgen from air (Nitrogen fixation). Doesn;t this contradict your point?

I do add Cal/Mag throughout the whole growth with each watering. However the amount is minimal, just so I don't get any deficiencies. For weeks 1-9 of flowering this is my schedule:

and in vegging:

And yes I have observed some clawing but I have related it to excess Nitrogen. (still not sure)

Here are a few images where the clawing is visible. It happens with every grow, usually stays in the middle of the plant.

So what do you suggest I do with the CalMag?

The nitrogen in the air must be run through a microbe (fixation) to be used by a canbabis plant. It can't be run through a microbe if its choked off.

Did you use Calmag shortly before the color change?

If your soil is low on calcium you need to use calmag regularly, or another calcium source.

Calcium is heavy and moves down constantly. If you let your pot dry out and the surface goes crusty and needs to be broken up, the calcium is low and magnesium has taken over as your premiere electrolyte and tightened the soil.

The tighter the soil the less nitrogen, so the bigger the nitrogen rush when you hit it with calmag.

This is why people lime their lawns.

See that line of clawed leaves in the circle of the picture I posted? I did that on purpose to demonstrate to others exactly what we are talking about here.

I let calcium get low until the soil tightened and the plant went light green. Then I hit it with calcium water and the leaves clawed across the plant, the plant darkened, and a growth spurt started.

So if your darkening/clawing occurred right after a calmag dose thats whats going on.

The tell is a line of clawed leaves all at the same level right across the plant. Thats the nitro rush occurring. It's there forever now as a scar.

Most people don't realize that in organics calcium is far more for the soil structure than it is as a nutrient. Its both a nutrient and a soil conditioner. It sets the stage for the entire grow. It is by a country mile the most important mineral in your soil. Thats why Cal/Mag fixes almost everything. It fixes the soil.

If that sounds like what your problem could be then you either need to mix more calcium into your next grow or use a low dose calmag solution regularly so the soil doesn't choke off.

Let it dry out. Is it crusty on top?

Be careful with calcium as it is an electrolyte so too much at once can fry your plant. Regular low doses are better.

Between oyster shell flour, gypsum, and dolomite lime, I add 1/2 cup of calcium source per gallon of soil when I cook my soil, and then I constantly topdress earth worm castings, which are calcium heavy, and water them in to keep the calcium flowing from top to bottom.

Every time your pots dry out check the surface for crusting before you water. If its there then calcium is low. Nitrogen is getting choked.

If you google both "nitrogen cycle" and "carbon cycle" and read it until you understand it, which usually takes a few reads, your organic grows will greatly improve.

You will understand why things happen as they do and soil inputs make more sense, so when you are buying soil or reading soil recipes they will make more sense when you read the ingredients.

No one adds nitrogen to nature, it comes from the air, and earth worms and weeds cycle the calcium round and round from bottom to top perpetually.

If your lawn has a dandelion problem or a thistle problem it's low on calcium. Those 2 weeds are calcium cyclers and have moved in to fix your soil.

All the nitrogen inputs in your mix, such as alfalfa meal, have been cooked (composted) and are now amino acids not nitrogen.

Plants get nitrogen throughout the season from the atmosphere.

If you are thinking of adding nitrogen to the pot after its growing, in the form of uncomposted meals such as alfalfa meal or blood meal, thats a bad idea. As soon as it comes in contact with raw carbon ( coco or peat moss) in your pot it will start to hot compost. Something liquid like hydrolysed fish fertilizer is a better way to go.

Also if calcium is low then your electrical charge on your colloidal platters is incorrect, and you are experiencing some mineral lockout whether you realize it or not.

The reason synthetic growers add calmag to the water 1st is to set the charge so the other ingredients are effective. Otherwise they lock out.

I can't guarantee thats what you got going on, but it happens regularly enough that I demo'd it to stop the same question popping up over and over.

Your before and afters are classic calmag results.

Next grow make note of the date when you add calmag to a light green plant and if a few days later its dark and a layer of leaves across the entire plant has clawed then you have your answer.

 

[SmokingWings]

If you are low on calcium then the magnesium in your soil will tighten the soil and choke air off. Air is 78% nitrogen.

When you add cal/mag the calcium addition neutralizes magnesium's charge, and magnesium's grip on the soil relaxes.

It works quick, almost on contact, and air rushes back in with a huge dose of nitrogen.

Quite often the effect is so profound the plant turns much darker and you see some leaf clawing too.

Later in the plants life you will see a direct line of clawed leaves across a level of the plant to remind you of it.

Adding cal/mag directly injects nitrogen from the air into the soil. Thats exactly what it is supposed to do and one of the reasons why you use it.

If it always happens at the same stage of the grow, chances are you are following a grow calendar and adding cal/mag right before each time you see the darkening/clawing.

This really caught my attention last night; big time caught it. By chance do you have sources for this info, places like agricultural, botany, or horticultural schools or universities or departments of agriculture at state or federal levels.

The majority of plants do not get nitrogen directly from the air through their leaves or through their roots. The nitrogen in the air has to be 'fixated' or 'fixed' first usually by being processed by microorganisms in the soil. These organisms are able to absorb the nitrogen and then during their life & death cycles they release the N through their waste or when their bodies decompose after dying.

While plants do get their nitrogen from the soil it is absorbed by the roots as nitrate or nitrite ions or as part of an ammonium molecule. The closest to what you are talking about it when ammonium molecules form in the atmosphere and are absorbed by water and fall during rain and snow. But, again, the nitrogen is fixed by becoming part of the ammonium.

While the legume family of land plants appear to be able to get nitrogen from the air it still needs to be 'fixed' by some sort of microorganism for the process to be successful.

The stomata on plant leaves open and close as part of the process the plant uses to absorb carbon dioxide for photosynthesis and release oxygen which is a by-product of the photosynthesis. These same stomata will open and close to release the water molecules as part of the plant's transpiration process. But the stomata are not capable of absorbing or releasing nitrogen molecules.

 

[SmokingWings]

This is what Chat GPD says about cannabis drawing nitrgen from air (Nitrogen fixation). Doesn;t this contradict your point?

There is nothing available to support the claims about Nitrogen made by the ChatBot if that is where it came from.

 

[bluter]

This really caught my attention last night; big time caught it. By chance do you have sources for this info, places like agricultural, botany, or horticultural schools or universities or departments of agriculture at state or federal levels.

i'm pretty sure he is equating it to how O2 is dragged down to the roots by water. any nitrogen it brings with the action will be fixated by the soil at that point.

 

[Gee64]

This really caught my attention last night; big time caught it. By chance do you have sources for this info, places like agricultural, botany, or horticultural schools or universities or departments of agriculture at state or federal levels.

The majority of plants do not get nitrogen directly from the air through their leaves or through their roots. The nitrogen in the air has to be 'fixated' or 'fixed' first usually by being processed by microorganisms in the soil. These organisms are able to absorb the nitrogen and then during their life & death cycles they release the N through their waste or when their bodies decompose after dying.

While plants do get their nitrogen from the soil it is absorbed by the roots as nitrate or nitrite ions or as part of an ammonium molecule. The closest to what you are talking about it when ammonium molecules form in the atmosphere and are absorbed by water and fall during rain and snow. But, again, the nitrogen is fixed by becoming part of the ammonium.

While the legume family of land plants appear to be able to get nitrogen from the air it still needs to be 'fixed' by some sort of microorganism for the process to be successful.

The stomata on plant leaves open and close as part of the process the plant uses to absorb carbon dioxide for photosynthesis and release oxygen which is a by-product of the photosynthesis. These same stomata will open and close to release the water molecules as part of the plant's transpiration process. But the stomata are not capable of absorbing or releasing nitrogen molecules.

This is exactly what I am talking about. If air gets choked off then nitrogen, of which air is 78%, gets choked, and microbes can't get it to fix into nitrates.

The microbes don't make nitrogen, they only convert it. They must 1st be supplied with it.

Low calcium strangles the supply chain.

I can't give you a particular single study to read as this is basic organic knowledge. It's how the nitrogen cycle works. There are likely thousands of studies on it. Try it out.

Stop looking at calcium as a nutrient and start looking at it as a soil conditioner and it becomes apparent quickly.

Also google calcium and colloidal platters and you will see another side of calcium and how magnesium is the Ying if calcium is the Yang. They need to be properly ratioed.

 

[SmokingWings]

I've looked into the info with regards to NPK uptake charts that you shared.

The charts come from a larger article (pdf format) that goes into greater detail. I have skimmed the article to get the gist of what is being said.

This brings up an important topic that has been very confusing for me along the years. One thing that isn't clear though, is if this uptake is for a specific week of the flowering or some rounded average. In other words is the N uptake in flowering the same in each of the 9 weeks?

I understand the question but at the moment I am not sure on a specific answer to the question. My take is that the amounts of N is a rounded average for the stages of the flowering period and not specific weeks. The amounts of N needed are higher in the first several week and start dropping as the flowering stage gets closer to the final weeks.

Over the years the major Cannabis fertilizer companies have slowly readjusted their schedules as to how much to use and when. I am noticing that they will start to drop the levels of N that the grower needs to provide for the last 4 weeks (approximately four) and have been increasing the amounts and the times when the other two macro nutrients need to be applied.

The other day I was looking up the general amounts of Phosphorous and Potassium flowering plants will need for their flowering stage. I was looking at not just Cannabis but also the popular vegetable plants and flowers grown by home gardeners. What I noticed was more recommendations to start applying at the very start of the flowering period instead of the past recommendation of applying after the start or when full flowering is taking place.

Based on what was being said my take was that the research was showing that the plants were taking in these nutrients earlier than science had thought and that the plants were processing and storing in preparation for the full demand that the flowering would placed on all the plant processes.

 

[bluter]

Based on what was being said my take was that the research was showing that the plants were taking in these nutrients earlier than science had thought and that the plants were processing and storing in preparation for the full demand that the flowering would placed on all the plant processes.

partly why a lot of the nute schedules are loading the plants up with N earlier in veg than they used to.

 

[Gee64]

This guy explains a lot in a manner thats easy to follow. Watch the whole hour.

 

[SmokingWings]

I can't give you a particular single study to read as this is basic organic knowledge. It's how the nitrogen cycle works. There are likely thousands of studies on it. Try it out.

I did check it out. No where does it say that land plants can absorb Nitrogen out of the air as you are implying. It has to go through the process where it is absorbed by the micro-ogranisms and converted which in the earlier messages was not mentioned.

The Nitrogen is in the air. The organisms process the nitrogen. The plants can then absorb the processed nitrogen. There is no way for the land plants to get the Nitrogen directly from the air as implied.

This guy explains a lot in a manner thats easy to follow. Watch the whole hour.

Do you have an article of that lecture printed out? Most likely I can speed read the article in a lot less time than the hour needed to watch the video. But, I did start the video and will watch/listen over the next few days.

 

[Gee64]

I did check it out. No where does it say that land plants can absorb Nitrogen out of the air as you are implying. It has to go through the process where it is absorbed by the micro-ogranisms and converted which in the earlier messages was not mentioned.

The Nitrogen is in the air. The organisms process the nitrogen. The plants can then absorb the processed nitrogen. There is no way for the land plants to get the Nitrogen directly from the air as implied.


Do you have an article of that lecture printed out? Most likely I can speed read the article in a lot less time than the hour needed to watch the video.

I give up. You aren't reading the posts. I have stated 2 or 3 times the nitrogen in the air MUST BE RUN THRU A MICROBE to become useable. I didn't try to help you out to get into an arguement, only to point you in a direction. Good Luck.

 

[SmokingWings]

partly why a lot of the nute schedules are loading the plants up with N earlier in veg than they used to.

.... and reducing or stopping approx 4 weeks before planned harvest. Plus increasing the P and K at the very start of flowering, before the flowers show, instead of a week or two after the start.

Another thing is the "finishers". It does seem that some new growers see finishers as a fertilizer that can be used the entire flowering stage and they run into problems. Even saw a company that is selling a flowering "finisher" mention a couple of times not to use their particular product until the last several weeks.

 

[SmokingWings]

I give up. You aren't reading the posts. I have stated 2 or 3 times the nitrogen in the air MUST BE RUN THRU A MICROBE to become useable. I didn't try to help you out to get into an arguement, only to point you in a direction. Good Luck.

Not once in msg #22 where you mention getting Nitrogen from the air. I cannot see anywhere a mention that microbes are needed to make the atmospheric Nitrogen available for the plant to absorb. And, that is the msg I am replying to.

There is mention of calcium, choked off air, soil tightening and other concepts. Even "Adding cal/mag directly injects nitrogen from the air into the soil. Thats exactly what it is supposed to do and one of the reasons why you use it." but no mention of micro-organisms being involved.

If you are low on calcium then the magnesium in your soil will tighten the soil and choke air off. Air is 78% nitrogen.

When you add cal/mag the calcium addition neutralizes magnesium's charge, and magnesium's grip on the soil relaxes.

It works quick, almost on contact, and air rushes back in with a huge dose of nitrogen.

Quite often the effect is so profound the plant turns much darker and you see some leaf clawing too.

Later in the plants life you will see a direct line of clawed leaves across a level of the plant to remind you of it.

Adding cal/mag directly injects nitrogen from the air into the soil. Thats exactly what it is supposed to do and one of the reasons why you use it.

If it always happens at the same stage of the grow, chances are you are following a grow calendar and adding cal/mag right before each time you see the darkening/clawing.

 

[Gee64]

Post 25 and 29 plus a video explanation in post 32 that you haven't got the time for.

 

[Roy Growin]

.... and reducing or stopping approx 4 weeks before planned harvest. Plus increasing the P and K at the very start of flowering, before the flowers show, instead of a week or two after the start.

Another thing is the "finishers". It does seem that some new growers see finishers as a fertilizer that can be used the entire flowering stage and they run into problems. Even saw a company that is selling a flowering "finisher" mention a couple of times not to use their particular product until the last several weeks.

Agree entirely and I practise your first sentence

I got a tester of a 'finishing agent' - it was basically tiny amounts of K, Mg & S but it appears to have a positive effect
Seem to remember Emmy telling me that Terpen8or was similar

As for NHO4 etc, does it really matter for your grow?

Anyway you are probably both right from your own understandings and some things get lost in translation/interpretation so No pasa nadal

 

[Wastei]

If you have signs of overfeeding that you don't like, why not just feed less? Problem solved!

Minerals accumulate in the medium and depending on your amount of runoff and feeding frequency it may add up in mid flower? From what I see you have two options, you can do is either feed less or increase runoff to better replenish the medium.

It's all about feeding strength and making the nutrients available and in range for optimal uptake by managing pH. I've seen many people including mods and reviewers on her giving the advice to add more minerals upon a already complete plant food. Most plant related problems are pH related in nature since we all more or less use a complete plant food with good mineral ratios. You can band-aid all problems which is a sub par practice. If you already have 150ppm per gallons of K in the mix and only 20% of it being accessible to the plant you don't solve anything by adding more, you're just masking the main problem and end up with other deficiencies.

 

[plan500]

The nitrogen in the air must be run through a microbe (fixation) to be used by a canbabis plant. It can't be run through a microbe if its choked off.

Did you use Calmag shortly before the color change?

If your soil is low on calcium you need to use calmag regularly, or another calcium source.

Calcium is heavy and moves down constantly. If you let your pot dry out and the surface goes crusty and needs to be broken up, the calcium is low and magnesium has taken over as your premiere electrolyte and tightened the soil.

The tighter the soil the less nitrogen, so the bigger the nitrogen rush when you hit it with calmag.

This is why people lime their lawns.

See that line of clawed leaves in the circle of the picture I posted? I did that on purpose to demonstrate to others exactly what we are talking about here.

I let calcium get low until the soil tightened and the plant went light green. Then I hit it with calcium water and the leaves clawed across the plant, the plant darkened, and a growth spurt started.

So if your darkening/clawing occurred right after a calmag dose thats whats going on.

The tell is a line of clawed leaves all at the same level right across the plant. Thats the nitro rush occurring. It's there forever now as a scar.

Most people don't realize that in organics calcium is far more for the soil structure than it is as a nutrient. Its both a nutrient and a soil conditioner. It sets the stage for the entire grow. It is by a country mile the most important mineral in your soil. Thats why Cal/Mag fixes almost everything. It fixes the soil.

If that sounds like what your problem could be then you either need to mix more calcium into your next grow or use a low dose calmag solution regularly so the soil doesn't choke off.

Let it dry out. Is it crusty on top?

Be careful with calcium as it is an electrolyte so too much at once can fry your plant. Regular low doses are better.

Between oyster shell flour, gypsum, and dolomite lime, I add 1/2 cup of calcium source per gallon of soil when I cook my soil, and then I constantly topdress earth worm castings, which are calcium heavy, and water them in to keep the calcium flowing from top to bottom.

Every time your pots dry out check the surface for crusting before you water. If its there then calcium is low. Nitrogen is getting choked.

If you google both "nitrogen cycle" and "carbon cycle" and read it until you understand it, which usually takes a few reads, your organic grows will greatly improve.

You will understand why things happen as they do and soil inputs make more sense, so when you are buying soil or reading soil recipes they will make more sense when you read the ingredients.

No one adds nitrogen to nature, it comes from the air, and earth worms and weeds cycle the calcium round and round from bottom to top perpetually.

If your lawn has a dandelion problem or a thistle problem it's low on calcium. Those 2 weeds are calcium cyclers and have moved in to fix your soil.

All the nitrogen inputs in your mix, such as alfalfa meal, have been cooked (composted) and are now amino acids not nitrogen.

Plants get nitrogen throughout the season from the atmosphere.

If you are thinking of adding nitrogen to the pot after its growing, in the form of uncomposted meals such as alfalfa meal or blood meal, thats a bad idea. As soon as it comes in contact with raw carbon ( coco or peat moss) in your pot it will start to hot compost. Something liquid like hydrolysed fish fertilizer is a better way to go.

Also if calcium is low then your electrical charge on your colloidal platters is incorrect, and you are experiencing some mineral lockout whether you realize it or not.

The reason synthetic growers add calmag to the water 1st is to set the charge so the other ingredients are effective. Otherwise they lock out.

I can't guarantee thats what you got going on, but it happens regularly enough that I demo'd it to stop the same question popping up over and over.

Your before and afters are classic calmag results.

Next grow make note of the date when you add calmag to a light green plant and if a few days later its dark and a layer of leaves across the entire plant has clawed then you have your answer.

I follow the logic but, a few things:

- I do supply the calmag with every watering, slowly increasing it from 0.1 to 0.4 within 5-6 weeks. There isn't a one time application that could trigger such an event.

- Also the recommended dosage is is 1ml/L and it give them only 0.1 to 0.4 which should be a safe approach.

- I can recognize cal and mag deficiencies and I rarely see them in less than 5% of the plants, so I bet I give enough calmag, or in the lower levels.

- Also I grow in Lightmix, initialy charged with some food to last for a week and then basically its peat and perlite. So lets root out any advanced live soils, soil amendments ect.

- I also apply properly brewed worm casting teas from week 4 of flowering until the end - roughly 50ppm is the tea after delusion. This includes some additional N and P (I add a little bat guano, that is high in P). Altogether, the tea can't be the issue here, I've skipped teas and it didn't improve or worsen 't anything visibly.

- My water source is considered nearly perfect with about 50ppm some of which is calcium. Also the nutres I use are organic, derived from Alge. It probably also has some calcium in it as manufacturer (Plagron) does not recommend adding any additional calmag.

Not that it is clear that I dont give the calmag at one concentrated dosage, but rather gradually and in small quantities, should I increase it or reduce it all togther if you still believe this is the issue with leaf darkening?


"Your before and after are classic calmag results." this is what I am not convinced of.