Yellowing leaves while flowering? Correct the problem with a high N food.

[Old Uncle Ben]

This study claims n and p are the interresting nutrients for big harvests and not so much k.

Interesting study, thanks for sharing. Seems in some cases the jury is still out. Hoo nose?

Given the limited number of studies and the relative importance of N on plant growth and development, collecting more information about cannabis response to N are needed to establish more accurate recommendations.

Phosphorus nutrition has long been a focus in cannabis cultivation. Growers often supply plants with relatively high P concentrations (up to 200 mg L–1) during the flowering stage based on a belief that high P promotes flower development. However, there is little evidence to support this practice.

Well, how about that LOL. Same position I wrote 20 years ago which can still be found in some cannabis forum FAQs.

"The never ending abuse of Phosphorous to enhance flowering

A common mistake for growers when they reach the flowering stage is to start hitting the plants with a high P fert like a 10‑50‑10, continuing to use this blend exclusively, and when their plants start experiencing a deficit of N, Ca, Mg or micros as reflected by the dropping of lower leaves and chlorosis, they wonder why. Plants flower as a response to long nights (or chronological age if equatorial), not because of food blends high in P (or K). A ratio of 10‑30‑10 is WAY too high in P. The plant will only take what it needs and compete for other elements that may be more important at the time.

You may have heard that too much N can inhibit flowering. No question about it, exclusive use of a plant food that is rich in N such as blood meal, a 5‑1‑1 blend, or ammonium nitrate/sulfate may inhibit flowering especially if the phosphorous level is low, but most balanced blends have sufficient amount of P to do the job. The question is ‑ "how much P is enough to support a good flowering response and still retain my leaves?"

Manufacturers/horticulturists will give you element analysis and what effect the elements have on plant growth, but remember this does not necessarily mean you will get better yields. Using a high P fert exclusively during flowering can actually work against you due to impending leaf drop. It's an abundant amount of healthy leaves going into 12/12 and maintaining their health until harvest that produces a lot of bud, not high P, or low N foods.

I rotate fertilizer blends as the plant *requires* them, not because it is "the thing to do." For example, when your plants are going thru the stretch phase during early flowering, they may need more N, especially if you're getting some yellowing in the lower leaves. Give up the cannabis paradigms and give them what they need. You may want to return to a mild high P fert when the stretch ends, maintaining the foliage in a healthy state of growth until harvest for maximum yields. A 1‑3‑2 blend such as Peter's Pro Blossom Booster, 10‑30‑20, is a good choice because of several factors ‑ it is higher in nitrate N and Mg and has a good micro package. It is sold under the Jack's Classic label.

There are many foods I stock in my toolbox. Dyna-Gro is another excellent brand. I use a lot of their Foliage Pro - 9-3-6.

Stay away from cannabis specific foods. They market unsuspecting newbies who don’t yet have a handle on plant nutrition and soil chemistry.

Uncle Ben"

 

[GMT]

View attachment 18839455


Yep, we got a nutrient imbalance going on here, notice the yellowing, and I don't think yours is a pure indica like my Lapis Mtn. indica that has leaves that go bronze, reddish, all kinds of weird colors. Be glad to advise ya kid but I think The Herd and their vendors have you by the balls. You've been programmed by the wrong people and now must submit to The Internet Cannabis Paradigms or be cast out by The Mob.
Good luck,
UB

Yes, it's a compost only grow to compare final weight with a fed grow under the same conditions with the same clone. No it's not pure indica, I haven't said it is. For that matter, while defending against strawman arguments, I haven't championed flushing either. It seems if you can't defend the central point at hand, you create a false version of the dispute. You didn't even give me credit for the pic. Nor the age of the plant or how long it had till harvest.
You're obsessed with this concept I'm a kid, because I've never heard of you before ? Or because I think giving a high n plant food to plants two weeks before harvest isn't the best idea? Either way, check out some of my threads rather than just the picture gallery, have a read, or don't. I'm always grateful to receive good advice, but I think we will forever see and do things differently. Each to their own.

 

[experienced]

, good on ya!

Peace,
UB

Wondering ... you in the Land of Oz?

 

[Hiddenjems]

Never had a green harvest yet which I preferred over yellowed/dead. Maaassive difference in terpene profile and potency.

Had a lot of cannabis from subpar sources (most believing their product to be superior) and the majority was green garbage.

Perhaps your stuff is different for some reason.

This. I’m not trying to grow the greenest healthiest plants. I’m trying to get the most dense overpoweringly smelly flowers.

 

[Loc Dog]

At week 6 you want them to yellow. Last thing you want is bud full of nitrogen at harvest. Or it'll smell and taste like hay. Let it yellow now, just water.

Is that week 6 of flower for 8 week strain?

 

[GMT]

That was my assumption for a pure indica.

 

[Ca++]

This. I’m not trying to grow the greenest healthiest plants. I’m trying to get the most dense overpoweringly smelly flowers.

The healthiest plants are more likely to grow good buds, than unhealthy plants are. Frame size and foliage quantity/health are directly linked to yield in all aspects.


P though stretch will grow good strong frames. People once thought N responsible, but it's P. K will promote more of a bush, If I'm to believe it has any use at all.

I think 60ppm P is high. I have been to 100ppm through stretch, which they liked, but it was accumulating in the coco. I have done that 600g a meter over n over with about 40ppm. Elevated levels of PK bring about early browning, and more recently I have seen it's likely the P part (I boosted P alone, having been able to prove it was K as I previously thought)

It does seem wise to balance K equally with N. Though their is no proof it's useful about about 30ppm, it is hard to believe we don't need it. However using more K than N just doesn't seemed useful at all. N should antagonise K, but I think the little arrow has fell of the chart, that says K antogonises N.



Tissue samples are not a great guide to feed needs. You may see Ca issues later in flower (for example) but feeding more Ca then, won't help. Lets be honest, after stretch the roots are not at their best anymore. They struggle to get Ca later on. At the same time, they become less selective. They start taking on feed that they didn't want. The samples start to loose meaning. Interpreting the numbers is complex.

 

[GMT]

For most of the plants life I would agree, but we aren't looking to present the healthiest plant at the Chelsea flower show, we're looking for the cleanest buds aren't we? We can care for the plant, or manipulate it to produce the best buds, and they are different.

 

[LungCooking]

The ego fight destroys the fun and the comparison kills the joy..
Plants coming from the same genetics have different phenotypes and genotypes.. Is all up to enviroment and.. genetic diversity... having a deep green plant doenst mean the plant is healthy..
One prefer his plants faded at the end of flowering, do it, the other prefer very green, do it.. some dudes only like green buds, others refuse golden ones..dont forget you are growing weed.. not tomatoes.. cannabis can grow very health with minimum food.. The way i see some people describing their skills with cannabis is like is some sort of god from the nature that nobody can beat it.. is just ridiculous.. specially people who have been around since the 70´s

 

[Ca++]

Here are some pretty pictures. Rows or plants, at different locations, with different soils, getting different measured amounts of N. I hope this covers genetic expression and environmental differences enough to look at N levels. Levels that don't stand alone, but are next to more rows with different K rates.
https://www.ncat.edu/caes/agricultu...mp-program/hemp-conference/files/mcginnis.pdf

 

[LungCooking]

Here are some pretty pictures. Rows or plants, at different locations, with different soils, getting different measured amounts of N. I hope this covers genetic expression and environmental differences enough to look at N levels. Levels that don't stand alone, but are next to more rows with different K rates.
https://www.ncat.edu/caes/agricultu...mp-program/hemp-conference/files/mcginnis.pdf

If you have the chance to grow all year round with different temperatures and humidities and same clones, you will know that the plant will behave and express differently..
Just cause it got more yellow at some point under certain temperature or weather doenst mean the plant was in need for more Nitrogen... and if was and the final product came with better taste with less nitrogen usage, why not?

 

[Hiddenjems]

First off, soil growers that think they can get highly detailed information from npk changes in such a buffered medium haven’t seen the speed and distinction of something like aeroponic results and crop steering.

I’ve grown some of the same clones in decent size monocrop setups for over 5 years. This is in different locations and growing methods. I’ve also manipulated nutrient ratios to get a more desirable crop.

I have found 100% of the time that focusing on keeping the plants green longer results in more overall plant mass, slightly less “a” quality bud, and much more larf bud. If I combine lollipop pruning with cutting back nitrogen, I get a good bit more “a” bud than either feeding method on its own.

 

[Ca++]

I agree Hidden. I will happily steer into bloom, with some lower N signs as my guide. Without them, things take a bit longer. I will then stop the N signs continuing once into bud formation. Going overly heavy on the N gives a more vegetative looking plant. I am a hydro grower though. Soil is often more about 'set it and forget it' with corrections made along the way.

Going back to the core reason for this thread, we have a pic of a plant that we are told recovered from a lack of N. I look at it, and see no reason to suggest it now has too much.

I do wonder about the Mg, but at page 4, I have perhaps left that too late.

 

[Old Uncle Ben]

This. I’m not trying to grow the greenest healthiest plants. I’m trying to get the most dense overpoweringly smelly flowers.

Well, isn't that too cool. And it's not leaves that produce "the most dense overpoweringly smelly flowers."?

Do you guys know anything about what makes a plant tick? Dats right, it's gotta be some crap like Big Bud.

Not singling you out. But the cannabis specific cons love ya man. 80% of folks here don't get it.

Uncle Ben

 

[Old Uncle Ben]

"Quality" bud is always anecdotal. I've seen bud around here I'd be embarrassed to show, but the grower is proud and he gets plenty of high fives from The Herd.....and that's OK.

My goal, no matter what the plant material, is to grow the healthiest plants/trees/shrubs/veggies I can and that starts with the root system, which most ignore here.

typical....

UB

 

[Old Uncle Ben]

Wondering ... you in the Land of Oz?

 

[led05]

Tissue samples are not a great guide to feed needs. You may see Ca issues later in flower (for example) but feeding more Ca then, won't help. Lets be honest, after stretch the roots are not at their best anymore. They struggle to get Ca later on. At the same time, they become less selective. They start taking on feed that they didn't want. The samples start to loose meaning. Interpreting the numbers is complex.

Foliar Ca is both a cheap & extremely effective way to get Ca into a plant, easy too

View attachment 18839896

Nice plants, good on ya!

Peace,
UB

TY UB - when I see the above plant I see excess foliage due over fertilization of N or perhaps just poor Haze genetics, maybe a bit of both, not trying to start a pissing match it’s just what I see, admittedly from afar

I grow all those species plants you’ve mentioned btw in the present and for many years too, I agree Cannabis is relatively an easy plant to grow, no arguments here

If you’re in Oz you’re already blessed with great weather & Sun, especially if you’re not in the mining wastelands of the west; though I’ve seen some sick grows from friends @ Perth region most that side seems tough to grow much of anything

Peace

 

[led05]

"Quality" bud is always anecdotal. I've seen bud around here I'd be embarrassed to show, but the grower is proud and he gets plenty of high fives from The Herd.....and that's OK.

My goal, no matter what the plant material, is to grow the healthiest plants/trees/shrubs/veggies I can and that starts with the root system, which most ignore here.

typical....

UB

9/10 people here are not farmers; clearly but mocking & condescension isn’t a good way to lead them towards betterment IMO

Perhaps impart some your knowledge in a more humble way; while also being open minded to others & their attributes - I promise you there’s people here whom can even teach an ornery old dog a few new tricks - and others whom would appreciate your knowledge much more if delivered in a more respectable way

You attract more flies with honey….type a deal

Peace UB

 

[WingzHauser]

Challenge - find me a link to a cannabis tissue analysis! That will reflect what NPK works best, start to finish. Example - I grow citrus and tissue analysis reflects it contains a NPK of 5-1-3 or 3-1-2.

Tissue analysis tells very little. Cannabis will uptake tons of nutes that cannot be metabolized. Plants cannot utilize iron oxide for example, even though Cannabis will take it up and displace it in exogenous tissue. Grow near a dusty chat road and your tissue result will be 10% calcium carbonate. Spray Manganese sulfate and it's oxidized on the surface. Tissue analysis will claim you have plenty, when sap has zero.


Uncle Ben. Where I'm from we don't mind yellow leaves, but when it comes to purple petioles, we don't smoke that stuff! We prefer our carbs in the buds not the stems. Converted to sugars, not stuck as starches. The only question is how much of this conversion should take place before or after harvest. Since curing is officially an ancient lost high technology in 2023 Id say before.

If phosphorus is responsible for sweetness, and potassium is responsible for sourness, and these flavors are the sole quantifiers in blind repeat purchase studies, can't we rightfully poopoo anyone who seems to ignore their importance while displaying visual deficiency symptoms of both? Anyone claiming plants want less light has lost me.

The only good nitrogen in bloom is cysteine and methionine. Feed those and you save the plant from wasted energy of nitrate reduction and sulfur assimilation. High iron means carotenoids, which norisoprenoids (many classic cannabis flavors) derive. High boron assists natural lipid profile and carb accumulation in buds. High sulfur antagonizes any Nitrate attempting to metabolize, high Mg assists "luxury" phosphorus metabolism. High molybdenum keeps residual Nitrate metabolism going and keeps your plants from turning pink at harvest. Etc etc.

Things you don't want: High Nitrate/ammonium, high calcium, high cobalt, that's pretty much it. Flushing is to remove calnit. All the Cannabis brands wouldn't come up with flushing agents (calnit antagonist formulas) if that was wrong. The further cannabis nutes can get from conventional the better.

Excess cysteine: converts to weed flavors in dark, after excess carbs are done converting to weed flavors.

Excess Nitrate/ammonia: Consumes sugars to turn into proteins in the dark. No energy left, no sugars left to produce cannabis flavors.

I get a kick out of growers preaching the evils of excess phosphorus when they grow phosphorus deficient plants and their fertigation method is tying up 94% of their phosphorus input, only to be released by algae in a duck pond down the road. It's almost as funny as the organic circus who bubble their compost until it's pathogen soup, then ferment some inputs (to bubble off any nitrogen?) in a separate trash can before feeding them high N barley flour, for da enzymes.

 

[Old Uncle Ben]

having a deep green plant doenst mean the plant is healthy..

As opposed to a sickly yellowish plant? You can't be serious.

Deep green also means it's indica.

UB