Why Flush?

Fungus Gnat

Fungus Gnat

Well-Known Member
missnu said:
Well I have grown and smoked a lot of pot...flushed, not flushed, underfed, overfed...whatever...and no popping as long as it is dry...and the thing about weed that isn't flushed not turning to white ashes is also ludicrous...I mean you can burn anything til it is white...and before it burns hot enough to white ash, it first becomes black ash with some substance to it...you keep burning and it turns white and well, ashy...lol.
That isn't guessing...nothing I said there was guessing...
People saying that the weed won't burn right if it isn't flushed just isn't true...if it was then paper that is covered in chemicals would pop and crackle when you burn it, and turn into black ashes...as opposed to the fact that it burns fast and quiet, and is reduced to white ashes..lol.
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Bud that is black and has trouble staying lit is more likely a lack of potassium(if dry). You need potassium for correct combustion of carbon hence the black residues...oddly it's probably healthier for you to not be smoking carbon.

Or maybe it's phosphorus, I forget.
 
chuckduck

chuckduck

Well-Known Member
Fungus Gnat said:
Bud that is black and has trouble staying lit is more likely a lack of potassium(if dry). You need potassium for correct combustion of carbon hence the black residues...oddly it's probably healthier for you to not be smoking carbon.

Or maybe it's phosphorus, I forget.
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Where did you hear all that? Do you have a scientific source we can read to back it up?
 
Huel Perkins

Huel Perkins

Well-Known Member
I found a great post today by another member on these forums that really drops some science about the true effects flushing has on a plant, its a great read!

riddleme said:
There have been a lot of debates on this forum about flushing and there is a lot of misunderstanding about it in general flushing has its place in gardening and in the real world (other than MJ forums) is referred to as leeching

This will be a long read but I hope it will set the record straight for everyone, this has been posted in several places here but I am putting to post together to clear things up a bit for all of you

first a ditty from Sensi Seeds with links verifying,,,

From an administrator at Sensi Seeds

"Advanced - Flushing

A critical look at preharvest flushing

Pre harvest flushing is a controversial topic. Flushing is supposed to improve taste of the final bud by either giving only pure water, clearing solutions or extensive flushing for the last 7-14 days of flowering. While many growers claim a positive effect, others deny any positive influence or even suggest reduced yield and quality.

The theory of pre harvest flushing is to remove nutrients from the grow medium/root zone. A lack of nutrients creates a deficiency, forcing the plant to translocate and use up its internal nutrient compounds.

Nutrient fundamentals and uptake:

A good read about plant nutrition can be found here.

Until recently it was common thought that all nutrients are absorbed by plant roots as ions of mineral elements. However in newer studies more and more evidence emerged that additionally plant roots are capable of taking up complex organic molecules like amino acids directly thus bypassing the mineralization process.

The major nutrient uptake processes are:

1) Active transport mechanism into root hairs (the plant has to put energy in it, ATP driven) which is selective to some degree. This is one way the plant (being immobile) can adjust to the environment.

2) Passive transport (diffusion) through symplast to endodermis.

http://www.biol.sc.edu/courses/bio102/f99-3637.html

http://www.hort.wisc.edu/cran/Publications/2001 Proceedings/min_nutr.pdf

The claim only ‘chemical’ ferted plants need to be flushed should be taken with a grain of salt. Organic and synthetic ferted plants take up mineral ions alike, probably to a different degree though. Many influences play key roles in the taste and flavor of the final bud, like the nutrition balance and strength throughout the entire life cycle of the plant, the drying and curing process and other environmental conditions.

3) Active transport mechanism of organic molecules into root hairs via endocytosis.

http://acd.ucar.edu/~eholland/encyc6.html

Here is a simplified overview of nutrient functions:

Nitrogen is needed to build chlorophyll, amino acids, and proteins. Phosphorus is necessary for photosynthesis and other growth processes. Potassium is utilized to form sugar and starch and to activate enzymes. Magnesium also plays a role in activating enzymes and is part of chlorophyll. Calcium is used during cell growth and division and is part of the cell wall. Sulfur is part of amino acids and proteins.

Plants also require trace elements, which include boron, chlorine, copper, iron, manganese, sodium, zinc, molybdenum, nickel, cobalt, and silicon.

Copper, iron, and manganese are used in photosynthesis. Molybdenum, nickel, and cobalt are necessary for the movement of nitrogen in the plant. Boron is important for reproduction, while chlorine stimulates root growth and development. Sodium benefits the movement of water within the plant and zinc is neeeded for enzymes and used in auxins (organic plant hormones). Finally, silicon helps to build tough cell walls for better heat and drought tolerance.

http://www.sidwell.edu

You can get an idea from this how closely all the essential elements are involved in the many metabolic processes within the plant, often relying on each other.

Nutrient movement and mobility inside the plant:

Besides endocytosis, there are two major pathways inside the plant, the xylem and the phloem. When water and minerals are absorbed by plant roots, these substances must be transported up to the plant's stems and leaves for photosynthesis and further metabolic processes. This upward transport happens in the xylem. While the xylem is able to transport organic compounds, the phloem is much more adapted to do so.

The organic compounds thus originating in the leaves have to be moved throughout the plant, upwards and downwards, to where they are needed. This transport happens in the phloem. Compounds that are moving through the phloem are mostly:
Sugars as sugary saps, organic nitrogen compounds (amino acids and amides, ureides and legumes), hormones and proteins.

http://www.sirinet.net

Not all nutrient compounds are moveable within the plant.

1) N, P, K, Mg and S are considered mobile: they can move up and down the plant in both xylem and phloem.
Deficiency appears on old leaves first.

2) Ca, Fe, Zn, Mo, B, Cu, Mn are considered immobile: they only move up the plant in the xylem.
Deficiency appears on new leaves first.

http://generalhorticulture.tamu.edu

Storage organelles:

Salts and organic metabolites can be stored in storage organelles. The most important storage organelle is the vacuole, which can contribute up to 90% of the cell volume. The majority of compounds found in the vacuole are sugars, polysaccharides, organic acids and proteins though.

http://jeb.biologists.org.pdf

Translocation:

Now that the basics are explained, we can take a look at the translocation process. It should be already clear that only mobile elements can be translocated through the phloem. Immobile elements cant be translocated and are not more available to the plant for further metabolic processes and new plant growth.

Since flushing (in theory) induces a nutrient deficiency in the rootzone, the translocation process aids in the plants survival. Translocation is transportation of assimilates through the phloem from source (a net exporter of assimilate) to sink (a net importer of assimilate). Sources are mostly mature fan leaves and sinks are mostly apical meristems, lateral meristem, fruit, seed and developing leaves etc.

You can see this by the yellowing and later dying of the mature fan leaves from the second day on after flushing started. Developing leaves, bud leaves and calyxes don’t serve as sources, they are sinks. Changes in those plant parts are due to the deficient immobile elements which start to indicate on new growth first.

Unfortunately, several metabolic processes are unable to take place anymore since other elements needed are no longer available (the immobile ones). This includes processes where nitrogen and phosphorus, which have likely the most impact on taste, are involved.

For example nitrogen: usually plants use nitrogen to form plant proteins. Enzyme systems rapidly reduce nitrate-N (NO3-) to compounds that are used to build amino-nitrogen which is the basis for amino acids. Amino acids are building blocks for proteins, most of them are plant enzymes responsible for all the chemical changes important for plant growth.

Sulfur and calcium among others have major roles in production and activating of proteins, thereby decreasing nitrate within the plant. Excess nitrate within the plant may result from unbalanced nutrition rather than an excess of nitrogen.


Summary:

Preharvest flushing puts the plant(s) under serious stress. The plant has to deal with nutrient deficiencies in a very important part of its cycle. Strong changes in the amount of dissolved substances in the root-zone stress the roots, possibly to the point of direct physical damage to them. Many immobile elements are no more available for further metabolic processes. We are loosing the fan leaves and damage will show likely on new growth as well.

The grower should react in an educated way to the plant needs. Excessive, deficient or unbalanced levels should be avoided regardless the nutrient source. Nutrient levels should be gradually adjusted to the lesser needs in later flowering. Stress factors should be limited as far as possible. If that is accomplished throughout the entire life cycle, there shouldn’t be any excessive nutrient compounds in the plants tissue. It doesn’t sound likely to the author that you can correct growing errors (significant lower mobile nutrient compound levels) with preharvest flushing.


​
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racerboy71

racerboy71

bud bootlegger
Huel Perkins said:
I found a great post today by another member on these forums that really drops some science about the true effects flushing has on a plant, its a great read!
Click to expand...
yah hp, riddleme was / is full of good bits, as is / was uncle ben.. read some of uncle bens posts if you really want to learn what makes a plant tick..
i highly recommend his garden tips and tweaks thread to anyone who will listen...
 
Beagle

Beagle

Well-Known Member
I planned on flushing my first run, it was ready to harvest before I got there....it turned out just fine, so screw flushing.
 
mipainpatient

mipainpatient

Active Member
Hi y'all, nice thread.
I've yapped about this topic before and am getting a little sick of copy & pasting myself so if you want the scope go crawl through my past posts like I do yours when you say good stuff :)


Quotes from this thread:

Huel Perkins said:
I've done it, 4 different samples lab tested showed no chemical residues in my "unflushed" buds.
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My question:
What chemical residues were you expecting to find?
Fungus Gnat said:
Bud that is black and has trouble staying lit is more likely a lack of potassium(if dry). You need potassium for correct combustion of carbon hence the black residues...oddly it's probably healthier for you to not be smoking carbon.

Or maybe it's phosphorus, I forget.
Click to expand...
I'm no expert on curing smokables, but I will give you this:
If you screw up the cure, it will burn black.


On flushing:
If you are a soil grower flushing can do two very stressful things to the plant.
1. Oxygen depravation
An ideal friable medium (friable = rootworthy if you will allow me the brevity) will be composed of 50% organic matter, 25% atmosphere, and 25% water and soluble ions. If you bump that 25% atmosphere out (by drowning the poor little innocent plant) for an extended period of time, you are bringing about a root die-off if it lasts too long and between that and the compaction resulting from your actions, the plant is going down fast. This is what happens to those people who always seem to kill their houseplants. They OCD-style overwater the plant and choke it out. How well a particular plant species can tolerate this state of flooding mostly depends on the presence of or ability to have aerial root structures. A great example of these roots is the corn plant. Take a look after a good rain, those roots aren't just breathing deep, they are anchoring the plant in. The orchid in my living room creepily seems to want to send it's roots towards where I sit on the couch. (medicated tangent, forgive me but I refused to delete it, but at least I covered the points)

2. Bacterial De-Nitrification
If you are growing in a medium which is composed of organic matter (soil = duh, but even coco coir and other "soilless" mixes may still get this effect, although if you get the right coir you could literally submerge the plant and it might still be able to breathe, think thin spaghetti) your plant is benefitting and suffering from the presence of Azotobacter species. They are referred to as nitrogen-fixing bacteria, because they are able to metabolize the N2 from the atmosphere and "fix" it into the soil because when they die, it is now a part of the soil structure via their organic-matter remains. What happens when the Azotobacter don't get to do it the easy way, by breathing the N2 from the 25% atmosphere present? They turn to any other readily available sources, even the plant itself if that were an option. If you flush aggressively you aren't just "washing salts out of the soil" which is a real effect, but the question regarding that remains:
if the salts were stuck in the soil and thus not making it into the plant matrix, wouldn't solubilizing them (getting them into solution in the water by diluting them with more and more water) just make them more likely to go into the plant matrix and thus landing your dreaded "salts" right where you were fearing they would end up if you didn't flush?
you are stripping the precious N from the soil itself and maybe even the roots of the plant itself and that is a stressor.

I think one of the misconceptions that people bring to the table with flushing comes with commercial (non OMRI-style chelate-based plant food) nutes. Why is it perhaps not in the best interest of the end-consumer and the plant as an entity itself to use such products?
Plants actually like the heavy metals present, in the way that a number of micronutrients (you can freshen up here:
http://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htm
I have study after study filed away referencing the incredible phytoremediation capabilities of C. Sativa (phytoremediation is the process of using plants to clean up contamination). This means that the species is noted for its ability to uptake heavy metals into its tissue or "plant matrix" meaning that if you serve it up fertilizers containing said contaminants, you better be damn sure it will end up in the finished product. Flushing will not draw these back out, if it did, phytoremediation would be reversed every time there was a heavy rain, where I suspect the opposite effect is more likely and it is enhanced, as in more water = more stuff can go into solution because the mass of the solvent is larger so the solute:solvent ratio is changing. Sorry to go technical but my brain does that kind of tangent too, especially with Kandy Kush, mmmmm.
Where was I (taps doob onto ashtray), oh yea. Salts...Ok so when you have houseplant and feed it tapwater, eventually you will see a salt buildup on top of the pot. If you watch the plant, especially if it is a more sensitive species, this salt buildup will eventually lead to a creeping necrosis starting at the tips of the leaves....this sounding familiar to anyone yet? (dead leaf tips that is)
Anyhow, according to several "master gardeners" I consulted, the best method is in fact to 1) put the pot in the sink and run water slowly for at least 20 minutes, until the salt layer re-dissolves and disappears (I know you know that warmer will make the salts dissolve faster but dude....don't do it!) and 2) begin a watering regimin whereby you administer water from the bottom of the pot, this may require a larger drip-catcher, and allow it to wick up. You could keep filling the catcher until it stops coming out empty when you return.
Ok so thats got the salts covered, but that had nothing to do with nutes.....
Whats in the nutes that also concerns me is the chelating compound most commonly used, EDTA. Used this a fair amount of times in the lab, not something you want in ya. Anyhow, before anyone calls me out, yes it is used medically but I am pretty sure you aren't smoking it in that scenario.
The other reason people opt for organic agriculture is erosion control. Commercial nutes correlate to soil bacterial holocaust. Some of these bacteria actually hold the soil together---think the adhesive properties of tooth plaque. Soil plaques reduce erosion and heavy soluble NPK administrations will dramatically alter the soil biota favoring erosion. Just trying to flesh out the related topics for you guys a bit.
Sorry to all offended by my ranting, felt damn good to get it out and hell, maybe someone learned something.
MPP out (and down, got work in less than 7 hrs)

edit:
stress may be your goal however, plenty of evidence supporting stress regimens for various results, if so, flush away! Hell throw the plant for a loop, use 40 degree water....
 
FatMarty

FatMarty

Well-Known Member
I sometimes flush for 'harvest' color inducement, and also when I plan to reuse the soilless mix I utilize.

Mostly it seems to stress the whole plant more than it helps late growth, etc.
That's what you guys wrote above; so...

I also utilize large saucers and do some feeding from the bottom to keep the water from running out prematurely.
I've found that if I give a dose down below with a dose on top in first application that when I come back for second application the pot absorbs more water/nute mix than without pre-waetting the bottoms first time.

The only time I got powdery mildew it was because of standing water in my bloom after a fan went down.
I used to just let it run off and let the fans dry it.
Bad move. It will catch up with you at some point.
 
K

kindfarms420

Active Member
one thing that is beneficial to just using water the last week or two (not flushing) is the fact that it starts breaking down the chlorophyll (which the curing process does) so it can give you better flavor quicker in my opinion i have taken harvest that weren't flushed first and they still tasted good but it took a month longer to get that really sweet flavor as to where the bud that i add water for a week or two has that sweet flavor a week or two earlier... but you can definatly have great tasting buds from unflushed bud as long as it wasn't over fed in its life.
 
Fungus Gnat

Fungus Gnat

Well-Known Member
chuckduck said:
Where did you hear all that? Do you have a scientific source we can read to back it up?
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Dear Ed,
I recently harvested my small indoor crop. My problem is the dried buds will not stay lit, which makes it impossible to roll into joints because the pot crystalizes into this black substance.
I read in a previous column of yours, that this might be due to a lack of potassium. I've tried various drying methods and none have produced pot that will stay lit. These included microwaving, sun drying for 1 - 2 days, and slow drying hanging upside down.
If the problem does indicate a lack of K, how and when should the nutrient be added?
My second question is that I am stuck with a 1/2 lb. of good looking and smelling pot which won't burn. Is there any way I can fix these buds?
Useless Green, Tallahassee,FL

and Ed says;
The black substance is carbon (C), which is what is left once the other substances have boiled or evaporated or burned. C by itself does not burn with a high enough heat to keep the fire going.When combined with K there is a higher burn temperature and the burn stays lit.
When wood or charcoal is burned, the ash which remains is mostly potash, K-2-O. In order to get a satisfactory marijuana, the fertilizer regimine should be changed.The plants should be fed a fertilizer with a higher ratio of phosphorous (P) such a 4-3-5 during the first few weeks of growth.This will help the plants develop short, stocky stems rather than thinner, taller growth.
During the last three weeks of flowering the fertilzer ratio should be low in N, high in P, and medium in K-between 1-5-3 and 3-7-5, (This stands for the ratio of N-P-K, always in that order.) or thier multiples. This encourages flowering, and causes a nitrogen (N) deficiency. The plant transfers N from it's old growth, the shade leaves, to the new growth, flowers and the small leaves surrounding them. The shade leaves turn yellow and die as the N migrates to the new tissue.
Your non joint burning marijuana may be a blessing in disguise. Instead of smoking in a joint, use a small bowl water-pipe or use for cooking.
You will get a much cleaner smoke since you are not smoking paper. The C of your K deficient pot does not burn, and the smoke is filtered of water solubles through water. Why would anyone want all that C or it;s pyrolitic, carbon monoxide (CO), which is considered a poison and CO2 in his/her lungs? Another benefit is that a pipe is much more efficient way to get high than a joint. Much less material is wasted as sidestream smoke in an effient pipe.
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Seems legit.
 
patlpp

patlpp

New Member
How can you blame people for suckering into flushing when almost all nute companies (including the sacred almighty holier then thou Dyna-gro) has the last week for flush. If the nute companies were supposedly totally out for your dollar, wouldn't they recommend NO flush so you would feed your plants another week? Canna is one that does not show to flush by the way.
 
Huel Perkins

Huel Perkins

Well-Known Member
patlpp said:
How can you blame people for suckering into flushing when almost all nute companies (including the sacred almighty holier then thou Dyna-gro) has the last week for flush. If the nute companies were supposedly totally out for your dollar, wouldn't they recommend NO flush so you would feed your plants another week? Canna is one that does not show to flush by the way.
Click to expand...
I don't blame anyone for getting suckered into flushing. In fact, i openly admit it in the very first post in this thread that i would flush my plants religiously because i knew very little and just followed the masses. The fact i was suckered into it and practiced the flushing strategy for so many years before ever experimenting with a different feeding techniques / schedules (not flushing or starving) was the whole reason i started this thread, i wanted to inspire people to think and try new things rather than just continuing to follow others who aren't experienced enough either.

Nute companies are out for your dollar, that's why they also sell flushing products...
 
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