k0ijn
Scientia Cannabis
It is though.
I have provided scientific evidence which shows pre-harvest flushing is a myth.
First of all you must make a distinction between flushing and pre-harvest flushing.
Nobody is saying flushing is a wrong thing to do, if you have grow medium imbalances or salt build up for example.
Pre-harvest flushing is based on a fallacy.
Nutrients are not stored in the calyxes, there is literally nothing to flush out.
I have provided all the info and links to references & sources in many threads, you can find the info with a simple search.
But for the sake of the argument I will show a quote of a post I've made:
All the information is out there, you can find it with a simple search of the forums.
But just to rest the case I've gathered up the points and links in one post (this is quotes of what I've written):
... I find it funny how you can still have unanswered questions.
Have you read all my posts on pre-harvest flushing?
The big debate in this thread is about _pre-harvest flushing_.
Not about leaching in general (leaching is flushing but is NOT the same as pre-harvest flushing), which has been explained by all of us against pre-harvest flushing many times, can be useful.
Leaching/flushing in general is thought of as to be:
Correcting grow medium errors.
Clearing salt buildup.
And just a general error corrector for solutions or medium in both hydro and soil.
Leaching is used by most growers, because problems tend to occur, even in the most perfect setups.
What we (especially Harrekin, SirLance and myself) in this thread who are against pre-harvest flushing state, is that pre-harvest flushing has not been proven to work for any of the reasons pre-harvest flushers claim they do it.
Many people claim improved taste, odour, yield, less harsh bud, better burning bud, better ash (whiter, cleaner) etc. etc.
They claim all kinds of wondrous things, which are apparently all thanks to the pre-harvest flush.
Although people claim this, there is no proof for any of it.
There are anecdotes of what people have done, there are stories, there are stories from authors (such as Cervantes, who is known to take information from other writes / growers and post it in his books).
What I have posted in this thread is a scientific study on the nutrient storage in plants, particularly ryegrass.
The study is very comprehensive and explains rather well about how nutrients are stored, where they are stored and what happens with the plants when nutrient levels are too high or too low (abundance versus. deficiency).
I will post the image from the study again showing this:
This explains a lot about the points in the discussion about pre-harvest flushing / leaching.
The study says that "growth requirements are generally achieved before high concentrations are attained".
This is a very important point.
Especially since this is about abundance versus deficiency (the optimal is 'critical').
What this study shows quite clearly is that if you underfeed the plants, the yield is affected quite heavily.
But what it also shows is that nutrient stored in the various parts of the plants change a lot depending on the levels on nutrients available (strength of the solution).
Since most experienced growers don't overfeed their plants but keep well measured levels of PPM, they can stray close to the 'critical' nutrient supply, giving their plants as much as possible without overfeeding or underfeeding.
We are not saying overfeeding is correct, we're not talking about overfeeding neither, we feed our plants as close to the perfect ranges of PPM as possible.
The points of Gastanker was that since plants store nutrients, and nutrients are stored all over the plant (including in the calyxes (buds)) and causing a deficiency will cause the plant to 'eat away' at it's nutrient storage, you will end up with less nutrients in the calyxes, therefore less nutrients in your final product, and the smoke will be less harsh.
You will not end up with 'chem bud' so to speak.
This theory is unfounded, and the study I posted contradicts this theory.
First of all nutrients are not stored in the calyxes so there is nothing to flush out.
That in itself should be the end of it but I'll continue explaining.
The study says plants are high efficient, they can consume nutrients before high concentrations are attained, and since none of us against pre-harvest are overfeeding, we are not achieving 'too high' concentrations of nutrients.
None of us have 'chem bud', we have all tried flushing, and not flushing, we don't see a difference.
We might even be receiving higher yields (which none of us have recorded however) if the study is the be correct (nutrient levels in the plant greatly affect yield).
What we do see a difference in is when you dry & cure properly versus dry & cure wrongly.
Drying & curing is probably the single most important step in any grow, it can cause mold, it can cause joy and it can be a pain in the arse.
But drying and curing is where your weed either ages like a good wine or crumbles, molds up and becomes useless.
Most people fail in drying & curing, many are somewhat successful, few master it.
I for sure don't master it, I'm trying to however, I invest in drying & curing equipment quite a lot and I am very careful.
That doesn't stop mold from setting in from time to time though, due to slipup or assistant error.
I'm not saying I don't want people to flush / leach their plants if they have problems with nutrient levels, salt buildup or anything else.
I'm not saying that you can't do what you want with your own grow either.
Where my problem lies, is with people trying to get other people to pre-harvest flush / leach.
When they claim all these myths about improvement of: taste, odour, colour, ash, harshness etc. it irritates me that people are just left to believe whatever this person writes, with no scientific backing, no factual information presented.
This is why I post these studies, why I try to show people the facts.
There are logical explanations to all those things.
Bad tasting weed, harshness and ash can all be improved by doing a proper dry & cure.
Most people have these problems because they do not know how to properly dry & cure.
To conclude, I don't believe in the surplus nutrients / substances theory regarding normally PPM'ed weed (as close to 'critical' as possible without overfeeding nor underfeeding) contra flushed / leached weed.
This is the theory brought up by Gastanker who said that you'll get a surplus of nutrients if you do not pre-harvest flush your plants.
There is absolutely no evidence for this, neither did Gastanker provide any evidence.
Plants which are in a deficiency do not 'eat away' the excess nutrients in calyxes, there are no excess nutrients or stored nutrients in the calyxes.
The plants basically eat themselves (yellowing leaves, withering leaves) to stay alive.
I don't believe that pre-harvest flushing / leaching your weed will give you better tasting, smelling and looking weed.
I don't believe you will yield more either.
In fact, I "believe" quite the opposite, I "believe" that keeping nutrient levels proper all the way to harvest, is the best way to get the most out of your plants humanly possible.
I mark believe because it in fact has nothing to do with belief.
It has to do with facts and whether you value logic, reason and evidence or not.
That is the great thing about science, you don't have to believe in it for it to be inherently true.
When you pre-harvest flush your plants, you starve your plants at the most important phase of growth, late blooom.
You cause a deficiency, which leads to (if we are to trust science) decreased productivity.
And most importantly, all the myths about pre-harvest flushing seem to be false.
Not one scientific piece of evidence has been provided by the pro pre-harvest flushing people.
You cannot find one study that proves any of pre-harvest flushings proclaimed positives.
Just to sum up with some references and sources:
Books & Publications:
Marijuana Chemistry;
Genetics, Processing and Potency
Cannabis and Cannabinoids:
Pharmacology, Toxicology and Therapeutic Potential
Plant nutrition - from genetic engineering to field practice.
Research and testing:
montanabiotech.com
http://www.cmcr.ucsd.edu/
I use sciencedirect.com and ncbi.nlm.nih.gov to look up publications.
There are a lot more references and source I could link to/quote/name.
But it would be a hell of a job naming them all.
I just named some of the most respected (peer reviewed scientific publications only) ones here, you can find loads more by searching on ncbi, sciencedirect or google in fact.
Read the publications, the books and the studies I've linked to and see if you come to a different conclusion.
In the end it's about whether you value science most or personal belief most.
