Flushing at the end of Vegetative State..?

I like this thread - good discussion.

I'd just like to point out that "nature" is an open system - rain does "flush" the soil it falls on, dissolving water soluble chemicals (organic or not, yes chemicals do exist naturally in nature) on its way down and out of reach of plant roots, all the way to the watertable. It's a constant cycle. Growing in pots is a closed system, what you put there stays there in one form or another unless you get rid of it, e.g. by flushing.

Jack, can you tell me how long it takes microbial activity to produce nutrients in soil to concentrations usable by the plants growing in it? If you were to flush all water soluble elements from an organic soil with a flood of water, how long would it take the microbes in the soil to break down whatever it is organic growers use as a precursor so that nutrients are again available to the plant roots? Not trying to argue anything here, I just don't know.

For the record, I'm in the no-flush-till-2-weeks-before-harvest camp, and I use the FoxFarm line of nutes (just the big 3, GB, BB & TB) with molasses in soil-less mix. Occasional foliar feeding with Ca/Mg as needed. And the flush I use isn't really a flush, more of a 2-stage watering. Saturate the soil but not to run-off, wait about ten minutes to give the water-soluble elements built up in the soil time to dissolve, then water again to a fair bit of run-off (but nowhere near a gallon or twice the volume of the plant's container of water or whatever most people mean by a "real" flush). Works for me, but I'm always up for some re-education.

Buddy Ganga said:

SunBiz1:, You stated that yellowing leaves are caused by the plant consuming it's own resources, while I contend it could be caused by depriving the plant of vital resources.

Actually I made both of the above statements.

starve the plant of any outside nitrogen or food.
aka depriving the plant of vital resources
The plant turns to itself and starts draining the leaves and older growth, that's what turns the leaves yellow
aka yellowing leaves are caused by the plant consuming it's own resources

Proper context man, proper context!

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Pot meet kettle, I never stated yellowing leaves ARE caused...I used the word could intentionally.


As per below:

"I'll re-post what you stated along with my response. You stated that yellowing leaves are caused by the plant consuming it's own resources, while I contend it could be caused by depriving the plant of vital resources."

amazingsandlad said:

I like this thread - good discussion.

I'd just like to point out that "nature" is an open system - rain does "flush" the soil it falls on, dissolving water soluble chemicals (organic or not, yes chemicals do exist naturally in nature) on its way down and out of reach of plant roots, all the way to the watertable. It's a constant cycle. Growing in pots is a closed system, what you put there stays there in one form or another unless you get rid of it, e.g. by flushing.

Jack, can you tell me how long it takes microbial activity to produce nutrients in soil to concentrations usable by the plants growing in it? If you were to flush all water soluble elements from an organic soil with a flood of water, how long would it take the microbes in the soil to break down whatever it is organic growers use as a precursor so that nutrients are again available to the plant roots? Not trying to argue anything here, I just don't know.

For the record, I'm in the no-flush-till-2-weeks-before-harvest camp, and I use the FoxFarm line of nutes (just the big 3, GB, BB & TB) with molasses in soil-less mix. Occasional foliar feeding with Ca/Mg as needed. And the flush I use isn't really a flush, more of a 2-stage watering. Saturate the soil but not to run-off, wait about ten minutes to give the water-soluble elements built up in the soil time to dissolve, then water again to a fair bit of run-off (but nowhere near a gallon or twice the volume of the plant's container of water or whatever most people mean by a "real" flush). Works for me, but I'm always up for some re-education.

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Your flushing technique is how I normally water, I allow soil saturation then re-water until I have a small amount of run-off. Yet, I use nothing but garden soil amended with molasses tea every other watering. The below pic is a 12/12 about a week from chop taken yesterday, the purple is inherent to the strain. Yet, you're using FF(who sells a flushing product)with good success.

*Scratches Head*

I think I need more horticultural classroom time.

amazingsandlad said:

I like this thread - good discussion.

I'd just like to point out that "nature" is an open system - rain does "flush" the soil it falls on, dissolving water soluble chemicals (organic or not, yes chemicals do exist naturally in nature) on its way down and out of reach of plant roots, all the way to the watertable. It's a constant cycle. Growing in pots is a closed system, what you put there stays there in one form or another unless you get rid of it, e.g. by flushing.

Jack, can you tell me how long it takes microbial activity to produce nutrients in soil to concentrations usable by the plants growing in it? If you were to flush all water soluble elements from an organic soil with a flood of water, how long would it take the microbes in the soil to break down whatever it is organic growers use as a precursor so that nutrients are again available to the plant roots? Not trying to argue anything here, I just don't know.

For the record, I'm in the no-flush-till-2-weeks-before-harvest camp, and I use the FoxFarm line of nutes (just the big 3, GB, BB & TB) with molasses in soil-less mix. Occasional foliar feeding with Ca/Mg as needed. And the flush I use isn't really a flush, more of a 2-stage watering. Saturate the soil but not to run-off, wait about ten minutes to give the water-soluble elements built up in the soil time to dissolve, then water again to a fair bit of run-off (but nowhere near a gallon or twice the volume of the plant's container of water or whatever most people mean by a "real" flush). Works for me, but I'm always up for some re-education.

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The microbial action breaks down the nutrients to their ionic form, and they are molecularly "bonded" to the substrate until they are released to the roots. This is why pH determines the availability. P, K, N, and other nutrient ions are - charged (anions) and the hydrogen ions they replace are + (cations) the charge is what holds them, and they do not "flush out" by merely rinsing out the soil with water. The amount of cations (+ Hydrogen ions) in the soil determines it's CEC or cation exchange capacity, and will tell you the amount of nutrients that the soil can hold and deliver.
Microbial action is an ongoing process, and is unaffected by rinsing out. But to answer your question, I "cook" new soil for a few weeks before I use it for plants, as it takes that long for the new soil to contain any usable nutrients from the micro-colony, IMHO. I've never done or read of any "timelines" for microbial production, but it is indeed a slow process.

flushing never hurts your plant. try useing 5ml per gallon of GH florashield, its not designed as a flush but it makes my plants very happy. PM me for pics.

Sunbiz1 said:

Your flushing technique is how I normally water, I allow soil saturation then re-water until I have a small amount of run-off. Yet, I use nothing but garden soil amended with molasses tea every other watering. The below pic is a 12/12 about a week from chop taken yesterday, the purple is inherent to the strain. Yet, you're using FF(who sells a flushing product)with good success.

*Scratches Head*

I think I need more horticultural classroom time.

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Lmfao.. It'll be alrite Sunbiz hang in there.. heh heh heh.. Nice lookin lady btw..

I don't see it as anybody's wrong or right here.. All valid edumicated opinions & viewpoints.. I think we should vote to have this thread sticky'd.. Lmao..

I flushed one and it still popped and snapped so I think it just needs to cure in a jar. If you want to restart your plant you cant flush because you will need high nitrogen to get it to grow back after harvest.

I personally do not flush at the end of a vegetative state because you will get a lot yellowing during flower. The plant will need the nitrogen for the first two weeks.

@Sunbiz1
I'm saying it's a fact that the yellowing is a direct result to the flushing and plant draining itself. There is no could be to it.
If you have that much problem understanding and accepting that fact, do some research and prove me wrong.
Maybe along the way you will stumble along the same information I found.

Buddy Ganga said:

@Sunbiz1
I'm saying it's a fact that the yellowing is a direct result to the flushing and plant draining itself. There is no could be to it.
If you have that much problem understanding and accepting that fact, do some research and prove me wrong.
Maybe along the way you will stumble along the same information I found.

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Pfft, think I'll have some dinner first.

As you are correct that organic soil does not have chemical salts added to it, salts will still build up if the pots are not watered thoroughly every once in a while (maybe once after vegging and once again towards the end of its life cycle. This is for getting SALTS out of the soil, not chemical nutrients added to the plant. Which a plant does not distinguish between a chemical nutrient and 'organic' nutrient. Flushing helps get rid of excess salts in a potted plant. I've grown organically and still got salt build-up, probably from watering just enough.

jewgrow said:

As you are correct that organic soil does not have chemical salts added to it, salts will still build up if the pots are not watered thoroughly every once in a while (maybe once after vegging and once again towards the end of its life cycle. This is for getting SALTS out of the soil, not chemical nutrients added to the plant. Which a plant does not distinguish between a chemical nutrient and 'organic' nutrient. Flushing helps get rid of excess salts in a potted plant. I've grown organically and still got salt build-up, probably from watering just enough.

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Subcool say's the same thing here..

http://bigbudsmag.com/grow/how/article/when-flush-your-marijuana-crop-september-2011

"This is for getting SALTS out of the soil, not chemical nutrients added to the plant."

Exactly.. Spot on.. !

TATTOODETROIT said:

Lmfao.. It'll be alrite Sunbiz hang in there.. heh heh heh.. Nice lookin lady btw..

I don't see it as anybody's wrong or right here.. All valid edumicated opinions & viewpoints.. I think we should vote to have this thread sticky'd.. Lmao..

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I view this site as a peer help forum, for all to achieve the same common goal. None of us have, nor will ever have complete knowledge on this nor any other subject. However, our collective experience when shared will help us all become better growers.

WestCoastMaster said:

Im sorry buddy, but if you dont flush your plants before you "chop" them your herb will not burn evenly due to built up salt in your buds. Your smoke probably has a slight snap crackle and pop to it and is probably harsh too.

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Pure conjecture repeated as fact. There is not one shred of evidence this is true.

WestCoastMaster said:

If you flush for 1.5-2 weeks before you harvest you will still get as good of a yield as if you didnt. Your not sacrificing yield when you dont flush your sacrificing taste and aroma. Cronic smells good, and taste good right? Its cause the flush homie!!!!!!!

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You WILL NOT get as good a yield by not feeding your plants for 1/4 of the flower period.

There are a LOT of very misinformed growers out there.
Hopefully this will help to clear things up for them up.

This is Proper Soil Watering Technique: Adding liquid to the soil until a small amount of liquid drains from the bottom of the container. (aka: runoff)
Best if done slowly.
The amount of liquid will vary depending on the size of the container.
The bigger the container, the more runoff.
The runoff liquid helps to rinse out any built up salts.
It's best not to leave the plant sitting in the runoff liquid.
Of course this doesn't apply to a seedling in a 5gal pot, lol.

Flushing Soil: Adding water at 3 or more times the container volume to attempt to rinse out severely built up/ toxic salts from the soil. Only should be done as a last resort.

Flushing - Hydroponics Technique :
Literally flushing or rinsing out of different nutrient solutions from the res, tubes, etc. during the different stages of growth.

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Somehow back in the 80's the term 'flushing' got morphed into meaning the extreme reduction of the ppm of hydroponic nute solutions for the last couple weeks of growing to try to achieve better tasting product. 'Flushing' out the bad tasting stuff. (It really doesn't work)
What actually happened was the better strains were starting to appear at the same time.
The growers unknowingly and egotistically took credit for the better tasting more potent product themselves.

You've just witnessed the myth in it's creation.

Sunbiz1 said:

...Yet, you're using FF(who sells a flushing product)with good success.

*Scratches Head*

I think I need more horticultural classroom time.

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I don't use the sledgehammer flush or any of their other solubles, just Big Bloom, Grow Big and Tiger Bloom plus molasses and Ca/Mg as needed (very soft water where I live).

jewgrow said:

...This is for getting SALTS out of the soil, not chemical nutrients added to the plant. Which a plant does not distinguish between a chemical nutrient and 'organic' nutrient. Flushing helps get rid of excess salts in a potted plant. I've grown organically and still got salt build-up, probably from watering just enough.

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That may be the purpose, but the result will be that anything water soluble (including ionic compounds other than salts) is going to go with the water running out the bottom of the pot. Flushing your soil isn't going to selectively rid it of salts, it's going to rid it of anything water soluble including salts. How do you think flushing gets rid of salts to begin with? Water, in the process of dissolving them, causes them to dissociate into a cation and an anion. That's what a salt is by definition. Most chemical nutrients added to the plant are composed of cations and anions and are going to be water soluble. Any compound with an -ate at the end, in addition to being able to form salts, is going to be water soluble (check your labels.) Potash (K2O) is water soluble. Chelated trace minerals are water soluble. They're all going, along with the built up salts, when you add large amounts of water through your soil. And tap water alone contains salts as well unless your water is soft. The crap that builds up on your shower head is salt, so most people are flushing out salts with water containing salts. Just thinking off on a tangent.

So yeah, the stated purpose of a flush might be to rid the soil of built up salts, but the result will be that it will rid the soil of anything water soluble. I don't grow organically (indoors, backyard garden is), but I don't buy the idea that you can't flush organic soil. If there's something water soluble in there (like "fixed" forms of nitrogen, phosphates and potash, the sources of your N-P-K), you can flush them right along with built up salts (hell, most are salts themselves). You might have the "unfixed" nutrients and microbes necessary to "fix" them left over, so you're not sterilizing it, but anything water soluble is going to go. Then usable nutrients will have to be built up again, which Jack Harer stated previously likely takes a few weeks. How is flushing organic soil two weeks prior to harvest not possible then, if nutrients aren't built up to appreciable levels by microbial activity in organic soil for several weeks?

I could be wrong, but I don't believe that the nutrient anions bound to the clay particles wash out. I am under the impression that the ionic charge keeps them in place until displaced by the plant roots secretions. P, K and others are made availabe fairly readily. I'm going to have to find out at what rate this actually happens, 'cuz now I'M curious. I will get back to the thread on it.

All great info, don't see anything there I can dispute! I do realize that not just salts are being leeched from the pot with a flush or large watering, but the main purpose of a flush of a potted plant is to get rid of salts. Of course your also flushing out other water-soluble chemicals...as well as some particles of your medium...which if its organic is reducing the amount of nutrients right there (although that's insignificant).

OK, I'm back with a bit of info. Once established and thriving, the microbial action is an ongoing continual process, and will replace anything that may be washed out, and will be up to almost full value within a day or so. I haven't heard back about whether or not the ionic form of the nutes wash out yet, but I'm sure I'll hear back tomorrow. This straight from the UT agriculture dept.