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To Flush Or Not To Flush


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Poll: To Flush Or Not To Flush (27 member(s) have cast votes)

Harvest Flush - Yes/No

  1. Flush (23 votes [85.19%] - View)

    Percentage of vote: 85.19%

  2. Do not Flush (4 votes [14.81%] - View)

    Percentage of vote: 14.81%

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#1 thinkinaloud

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Posted 01 November 2011 - 10:10 AM

Discuss Harvest Flush only. I shamelessly borrowed this writeup from somewhere. To original author- thanks! Feel free to post your opinion and why. BUT direct/personal attacks WILL NOT BE TOLERATED! Description of Harvest Flush: 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: The nutrient uptake process is explained in this faq. 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. ‘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. 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 needed for enzymes and used in auxins (organic plant hormones). Finally, silicon helps to build tough cell walls for better heat and drought tolerance. 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. 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. 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. 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 pre-harvest flushing. Drying and curing (when done right) on the other hand have proved (In many studies) to have a major impact on taste and flavor, by breaking down chlorophyll and converting starches into sugars. Most attributes blamed on unflushed buds may be the result of unbalanced nutrition and/or overfert and unproper drying/curing.
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#2 Dudz

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Posted 01 November 2011 - 11:40 AM

I believe that flushing can/does impact yield. If you aren't feeding them, they're starving and having to steal the stored energy from their own leaves. This is obviously going to slow growth of buds post-flushing versus giving them as much food as possible and not flushing.

However.... aside from any chemical or nute flavors - which can easily be argued either way:
Getting the plants to "fade" removes quite a bit of chlorophyll. Chlorophyll is not only poisonous to the human body, but it also makes the smoke more harsh on the lungs ....and affects the smell and flavor. Chlorophyll has its own scent and flavor - removing as much of it as possible before ever getting the buds into the jar helps the other flavors and scents come out more. It is for these very same reasons that I am also quite anal about closely manicuring the buds. I remove as much leaf material as possible when trimming. Some people go yet another step and water-cure their buds to further remove chlorophyll. Water curing is something I am not a fan of, as it also removes a lot of other smells and flavors.


My more personal opinion:
We spend a ridiculous amount of time doing everything we can think of to grow these plants to perfection. To not perform this rather simple step in order to make your medicine smell, taste, and smoke as smooth as possible ......is basically an insult to all the love and hard work you have put in over the last 4-5 months. I grow for quality, not quantity. I'd rather have 4oz of well-manicured, flushed, and properly cured medicine than I would a full pound of the same meds that were not taken care of at the end.

Edited by Dudz, 01 November 2011 - 11:43 AM.

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#3 OrangeSkunk

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Posted 01 November 2011 - 12:08 PM

is there a middle ground, what if your flush solution contained some of the immobile elements?
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#4 KnuckleDragger

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Posted 01 November 2011 - 12:18 PM

I've kind of looked at this and I want to try something along the lines of Maxibloom (5-15-14) at 1/2 strength+molasses for 5 days, 1/4 strength for 5 days and then just molasses for 4-5 days then a clear flush and 24 hours darkness then hack'em up. :woohoo:
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#5 Your Grandfather

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Posted 01 November 2011 - 12:46 PM

Immobile elements are totally worthless to the plant, and if their basis is salt, their presence will have a negative effect on the roots, which will manifest itself in the plant. Somewhere in that nice cut and paste job there is reference to the elements which have to be in your soil in order for the plant to achieve it's maximum potential. Plant roots and endo fungi are only capable of moving (mobile) food which is water soluble. Elements which are not mobile (immobile) can not be uptaken by either the plant roots or VAM. That is why they are called immobile elements. All food (elements) flows into the cell across a membrane, this is basically cation (cat ion) exchange, which is the movement of ions (food). We can have a lifetime supply of food in direct contact with roots, but if the food is immobile, meaning we cannot make ions flow, it is absolutely worthless because of that simple fact. IMHO, once a person understands this, then the real reason to flush becomes clear. To remove the salts from the rhizosphere so as not to affect the final yield. It is hard to move fluids up into the plant (colas) when you have a big pile of salt, the moisture won't leave the salt for the plant. If we don't move the fluid up into the bud, our harvest will suffer, therefore it makes sense on this level to flush the living shit out of the soil/medium. The conversation about pathways inside of the plant are secondary. First you have to get the food into the plant. Personally I don't flush, but I can understand why people would want to do it.

#6 usstoner

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Posted 01 November 2011 - 04:30 PM

since i use chemicals i always flush 2 weeks before harvest... and i also flush once a month because i'm a heavy feeder... always had good results...
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#7 mediuseA

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Posted 03 November 2011 - 04:40 PM

bump muA
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#8 GrowGoddess

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Posted 09 November 2011 - 08:11 PM

For being a 100% organic grower, no chemicals, I do not flush at all. The last two weeks of flowering, I prefer to dry stress the plant. I do this by minimal watering and the last couple of days do not water at all. That is just the way I prefer to do it. :bong:
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#9 thinkinaloud

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Posted 14 November 2011 - 11:17 AM

Same Strain

Indoor, Chem Hydro, flushed VS Outdoor. Organics, not flushed


Bag appeal-
INDOOR! big hard nugs Outdoor, small pop corn buds

High-
Both are amazing! head and body!

Taste-
Organics tastes AWESOME! Hydro had about half the taste


Next Day- flush affects
Organics - i feel dumb. Slow and in a fog.
Hydro- all good and ready to GO.


Total trade off!
But I need my BRAIN!

I vote for HYDRO and FLUSH!

Edited by thinkinaloud, 14 November 2011 - 12:54 PM.

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#10 thinkinaloud

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Posted 15 November 2011 - 06:41 PM

Organic non-flushed VS flushed Hydro EC readings over 24 hours


Same mom (Diesel X Kush from Rezdog)

Flush/Cure:
Flushed hydro (freezer cure)
Not flushed organics (basically open bag cure but its still fresh)

Hydro was flushed till hydro water read <100ppm (after a period of hours)
Organics was TLO and just h20. Then, cut.

Nutes:
Organics:
Some maine organic soil + fish emulsion
Hydro:
GH lucas + Kool bloom powder.



Bag appeal- (atleast in this case)
INDOOR- tighter bigger nugs
Outdoor- much larger % small airy popcorn buds

High-
Both are amazing! head and body!

Taste-
Organics tastes AWESOME! full bodied loveliness! Kush and Diesel are EASY to identify
Hydro has about half the taste. Cant easily identify the distinct tastes. (even with all my scent efforts)


Next Day Effects-
Organics - I feel noticeably dumber. Slow and in a fog.
Hydro- All good and ready to GO.


I've been able to replicate this Dumbiness effect with badly flushed hydro bud and now non-flushed organics. By some standards, I maybe jumping to conclusions. I am firm believer that the theory is sound.

Awesome if someone would compare a flushed organics vs non-flushed organics.

I'll test this water leeching on buds post cure.

Conditions:
Same weight, same tap water (no R/O), same conditions, over same time period, and of course same meter. (sm802)

.5 g of each sample size
washing probe between each sample

starting tap .08 EC

EC readings
Organic Hydro
1 H .28 .26
2.5 H .35 .36
4 H .40 .41
13.5 H .60 .61
24 H .73 .77

not much of a difference in EC readings
conclusion: same about the water soluble salts in organics (non flushed) and hydro (flushed).

between readings, glasses were in a dark cabinet.
next time.. i am going to add h2o2 to the water cure.

Given buds had the same weight but 3 organics to 1.5 hydro nugs of same dimensions, I am not sure how to interpret how the glasses look at 24 hours.

organic looks green/browner and a film on top of the water.
hydro has no film and lighter green.

In a few days, i'll test the organic to see if the same dumbiness reaction happens.
see if the issue is water soluble.

Pictures. leftside is hydro right side is organics.
(Organics has white leaf!)

Attached Files


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#11 thinkinaloud

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Posted 16 November 2011 - 12:39 PM

Conventional wisdom has been Organics are cleaner than Chemicals. But my body doesnt agree. I want to figure out why. By no means, can we draw an major conclusion with these experiments. EC measures salts. Salts might not be the issue. Just mean to question our assumptions. Which i believe is the spirit of the original poster's question. Pictures after the experiment. If you had to drink one, which one would you drink? Want to guess which one is organic?

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#12 Blue61

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Posted 17 November 2011 - 02:45 PM

My last grow I had a bad spider mite infestation and one of my girls was definatley not going to make it to full flower so I took her down with about 2 1/2 weeks left.I did not flush her and I used chemical nutes on all of them plus they were clones from the same mother.The only difference I noticed was she was a little harsher.The other 3 which got flushed tasted the same and had the same potency just smoother.

I have noticed using chemical nutes and this is just imho that the salts build up and when you flush I think it actually allows for some of those nutes to be up taken by the plant and in an effect it is almost like feeding them one last time.
From everything I have read it seems it takes the plant 5-7 days to effectivly use the nutes so flush a week before harvest I don't believe hurts the yield much at all if any.
Later,
Blue

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#13 red662

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Posted 05 December 2011 - 06:25 PM

if im using bio bizz products i dont bother with flushing if using anything else i would normally flush nightly say 2 pints of water a day for week n half and ur laughin i have yet to have any complaints about my smoke. a friend of mine use's an advanced nutrient called final phase, bloom enhancer http://www.advancedn...information.php he swears by it its expensive, iv tasted both water flushed and this as a flush have to say it does leave a nice clean taste. depends on how much u wanna spend, if ur like me just flush say 10 days fro home and daily, the leaves will turn yellow from the bottom up just pull these off as its getting ready fro harvest and the leaves fallin of is from the flushing and a good sign that uv cropped at the right time, in mu opionion id have to show u what i mean but theres method to my madness hahahahaha. as longs as u can get the fert/chemical taste out ur aughing and plenty of flushin, dependin on how much u wanna pay ur talkin tap water or some flushing gaent that work s equally as well but tem times the cost depending on what type water u drink lol,
peace

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#14 Tasty0Trainwreck

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Posted 13 May 2012 - 02:49 AM

in my opion flush is a must but im am also hydro heavy feeder.. but i have cut fat nugs off due to breaking off with no flush and noticed very little diference in taste.. i mean it is 2012 these nutrients are specificaly desinged for our plants now...i say what ever works for you stick to it cuz you shoudnt fuck with good results
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#15 Bong

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Posted 31 May 2012 - 05:32 AM

i'm a big fan of flushin my last baby was a blue cheese clone, it was flushed for 12 days and the smoke was epic. i tried sum jus before i started flushin a branch broke due to too much weight from the nug, flush gets my vote everytime cleaner less harshness and my leaves yellowed the longer it flushed which told me wen she was redi. i like the clean taste from fresh water : ),,,,,,,,,,,,, bonghead
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#16 strider

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Posted 31 May 2012 - 05:58 AM

Our organic girls don't get any nutes after about days 50. The last two weeks they get nothing but pure, clear water. No flush at all.
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#17 stocktonT

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Posted 11 February 2013 - 05:43 PM

There's only one situation (that I can think of anyways) when I would flush, and that would be if a plant shows signs of being over feed (too much nutrient added) and you see the plant "burning". Then a flush would rid the excess salts from the roots and you can start over with a fresh nutrient solution (regular feed). Always give the plant what it needs, when it needs it, even the last weeks of flowering (when a lot of bud production is taking place). I have tried to flush last two weeks, both with loads of water, and with flushing agent (waste of good money). I have tried to cut out N totally last weeks of flowering as they say cutting out N from the feed would make it taste less of chlorophyl. I have tried the same strains (cuts off of the same mother plant) both flushing and without flushing and never ever noticed a difference in taste, smell or high. Only thing I have seen is: by giving the plant all the nutrients it needs (even last weeks of flowering) it produces more (bigger) buds.
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#18 plant boy

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Posted 12 February 2013 - 08:49 AM

the plant tells you when it is done feeding as it will stop drinking as much @ that time i start using just water to finish her off
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#19 Bong

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Posted 12 February 2013 - 09:29 AM

the plant tells you when it is done feeding as it will stop drinking as much @ that time i start using just water to finish her off

i agree pb let the fade begin :D
bonghead
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#20 EmeraldCityOasis

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Posted 30 November 2013 - 09:32 PM

thanks for sharing, this was good information.
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#21 chow

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Posted 30 November 2013 - 11:27 PM

flush
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#22 KnuckleDragger

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Posted 04 June 2014 - 09:50 PM

bump


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#23 BikerPepe

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Posted 11 July 2014 - 03:22 PM

I'm with a few others here... I don't really "flush".  My methods were handed down to me from the old school growers up here.

I grow in Black Gold Organic soil, I use Miracle Grow and Bloom, sparringly at a few strategic points in the grow and FoxFarms main 3 in between.

I alternate as the plants tell me and I switch to plain water for the last 3 weeks before harvest.  I consider it a more natural, slow type of flush.

I also clip tight to the nugs (I hate shabby lookin' bags) and use all the trim to screen and make tincture.  I don't hang my weed though... and most do.

I find it much easier to trim with less damage to the final product and with a slow cure in a cool, dark place (about 1.5 - 2 wks.) the final products has never let me down.






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