Lets talk about flushing and coco.

First I want to say, coco is a wonderful medium. Its very versatile, very forgiving, and just all around great. I love it. I started growing with coco 5 years ago and never looked back. I also recognize that flushing can be a very important tool to a good harvest. I am not talking about cleaning your coco, although much of it is good to go out of the bag.

In that time I have experimented with several different watering, feed and flush cycles. This is what I have found based my experience over these years:

1. Flushing in coco is not mandatory, in fact it can even be counter productive.
2. Flushing should be used only when needed.

The Old Guard:
I remember the first time I brought up the subject on my second grow. I nearly got lynched from the forum I was at by some users because it had been drilled in there heads for years and years that flushing, especially with hydroponics was an absolute must do. After all, Hydroponics means man made, ergo, its toxic and full of shit that will melt my lungs if I don't flush...right? Well....uh, no.

Surely you need to flush when you switch from veg to bloom right? Nope.
What about run-off? Sorry, no.
Seriously, you don't water or feed to run-off at all? Nope, I water what I need to according to the weight of the pot.
What about salt build up? What about it?
You probably have issues with that. Not really.
So let me get this straight you water/feed just enough for the plant and thats it? Yep, pretty much.
Ok, so you're using organic only then? I use both, but mostly synthetic. Neither seems to make a difference.
You use synthetic blends and don't flush? That's heresy! Well, thats just like, your opinion man.

I understand why some people might feel this way, but a harsh, hey-like, or chemy tasting smoke has more to do with your cure then how many times you needed to over water your plants. Thats right, I said "Over Water", because that is what a flush is. That snap, crackle, and pop is not due to "chemicals", its due to a crappy cure.

If synthetic nutrients have any faults, its more of what they are lacking compared to organic. Whether an element has been processed by nature or by man its still the same element. Im not going to go into organic vs synthetics, all I will say is both are great, and leave it at that.

So...why does "x" do it in coco?
There could be a few reasons:

It's they way they have done it since they started, and thats the way they roll.
It saves money.
It's a commercial grow and they blanket flush all their plants because they can't check every plant.

Plants growing in pots larger than 5gl/20ltr require a much different watering and feeding schedule compared to a typical hand water or closet grow. There is much more water involved, lots more medium to saturate, and more time due to its size for salt and excess nutrient build up. Again its more of a blanket precaution. Something thats probably not going to be a problem for a 3 month grow in a 1-5 gallon bucket, there simply is not enough time for that to happen if feedings and waterings are done at correct proportions and ratios.

So I should never flush?

That's not what I said, its a tool. You should flush when its necessary, when your plant looks like it needs it. I.E when you can't figure out what the hell is wrong and you need to start from square one.....or when it makes sense for your situation, which brings us...

Full Circle:

With all this being said I still flush when I harvest sometimes. Why? For no other reason than to save money and be lazy. The plants are going to die in a week or so anyway. Why waste the nutrients, let the plant vampire its fans for extra nutrient if it needs them.

Final Thoughts:

I guess my point is whether you feed up until harvest or flush for a week before does not seem to make any difference in taste or smoke as far as I can tell and that its entirely possible and even desirable to go an entire grow never having to flush once.

Keep toking.


Thoughts, feelings, ridicule?

[Edited: I felt I needed to sum up my point to this post on re-reading, lol]

This all sounds entirely rational. From my experience, this rings true. The water holding capacity of a medium is important, and to saturate unnecessarily would absolutely be counter productive. And while yes, there could be potential for excess salt build up, I wouldn't be doing a flush every water as you'd more than likely be removing (wasting) nutrients in the pot. Monitoring the plant for signs of stress (over fertilisation or deficiency) should always be the key rather than following a set methodology.

Completely agree on the synthetic vs organic comment. I practice as near organic methods in my outdoor vegetable production, but this is for a range of reasons (largely based on self sufficiency, keeping costs down and not using more petrochemical based products than I need). As for hydro or even in general, I still don't have an objection to the use of chemical fertilisers on plants - as you say, the chemical elements will be taken up by the plant regardless of source. If I buy into any of the organic dogma, it's that organics provides extra goodies which industrial/chemical options don't - and that if anything is what will effect yield, quality, taste, smell etc.

As with any horticultural practice, there are methods and tools available to the grower. And making the best use of them is key. Solid post +rep

it's very good practice to "leech" the medium once in a while, especially if the plant has been in there a while and you think salts could have built up on the roots.
the water will cleanse the excess salts off the roots and help them uptake nutrients better
IMO you can do without a leech and grow successfully, i just like to do it when i really have been giving it nutes and i think it could use a little cleaning
leeching is running 3x the medium of water through, i like to leech my 3L coco hempies a month or more after they are put in there.
i use 1/8 or 1/4 dose nutrients to do it, because I'm more afraid of shocking the plant than I am cleaning the roots.
after the leech i'll give it a 1/2 dose nutes, and a day or so later when the medium dries out , i'll step back into full

i love coco and have only used the compressed, shitty pyth type. I am really looking forward to a quality grade coco that doesn't need the extra work prior to planting (rinsing, soaking, charging, buffering)

just saying the place i see in "flushing" which is 5x the medium (example, 5 gallon gets 25 gallons of water poured slowly through it) is not flushing
IMO leeching is what should be done, to prevent the excess salt buildup.
people will flush when they make huge errors, and i agree that you really don't need a final flush, but why the heck not (I do it like a day before chop though)

the nutrients i use are pretty cheap though, so i don't mind "wasting" them an extra week, i agree the cure is what gives you a clean smoke. It's also important though to not overdo the nutrients and burn the plant at all
i like the post a lot though, good stuff man. i hear where you're coming from

Thank you cannaculturalist, what kind of organics do you work with? I have been tempted to cook my own but I would stink out the locals.

Nizza I agree on leeching, I mean thats basically what is going on when you water/feed/water. Try canna, not one single problem, ever. I used one of those bricks and hated it. Its worth the extra 10 bucks or whatever. If you can't find in your town its worth a drive.

Thats also what I am saying about feeding up until. I have fed all the way up till harvest (with last day of water), and everything tasted just fine. In fact it tasted no different than plants starved for a week.

Most of what I currently do is limited by space, but involves composting and vermiculture. I am extremely keen to get into humanure decomposition/production, but unfortunately my current arrangements don't allow for it. To this I practice where I can organic methods of crop rotation, fallow periods, green manures. Living in the city doesn't allow for me to go further and integrate larger permacultural ideas including animals or larger integrated plantings, but have worked with them and continue to do so with others. Despite the common perception that composting etc is smelly, if done correctly it is incredibly neutral - in fact even having an onsite humanure composter wouldn't be a problem, I just lack space and setup. It all comes down to what is practical within the given space/area.

Though I will chime in regarding coco, and suggest that as a hydroponic/soilless medium, it is important to work appropriately with the setup of the planting container, plant and schedule. That is, as you say, to water/feed/water and cycle the system (the pot with medium and roots) - and perhaps more important with using synthetic fertilisers in the absence of any organics (which would normally fulfil the duty of cleaning/buffering the system from excess build up). If the system is sterile, manual manipulation would be more called for. But again, depends on what you're trying to do, the scale and effect on plant life.

As for leeching prior to harvest - I haven't experimented with this one myself to say, however in my forth coming grows, I will be trialling it. The idea of making the plant canabalise itself to a degree, to reduce additional nutrients from itself does make some sense. My oldschool hippy father taught me how to water cure bud and leaf to remove water soluble elements to 'clean' the consumables post harvest - this isn't ideal and is time consuming, but has proved effective on some harvests. This would perhaps do a similar job of sorts preharvest.

cannaculturalist said:

Though I will chime in regarding coco, and suggest that as a hydroponic/soilless medium, it is important to work appropriately with the setup of the planting container, plant and schedule. That is, as you say, to water/feed/water and cycle the system (the pot with medium and roots) - and perhaps more important with using synthetic fertilisers in the absence of any organics (which would normally fulfil the duty of cleaning/buffering the system from excess build up). If the system is sterile, manual manipulation would be more called for.

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Right on! We are on the same level.
View attachment 2949881

+rep

I just started mainlining 4 clones and look forward to that. I might stop by your log if you don't mind.

In the end, I flush yes to save on nutes and out of a sense of responsibility, or an old habit? Anyway, the flushing during growth is different procedurally and for reasons essential for most coco users. The solution is simply diluted to 500ppm and given a longer top feed. The buffer is reset at 5.8 and salinity is greatly reduced. Plant health is why I do it and why I recommend doing it.

I am less than 48 hrs from harvest. I have had these 2 ladies on a 350ppm (5.8ph) diet for 8 days. Down from the flowering level of 1.1kppm

I do not like the idea of going completely nuteless, since I do not think this happens in nature. Granted, they do not get a regular platter of 1k+ ppm either...lol

I can see the change in the plants, albeit a much smoother transition to finish without a ton of leaf drop. I personally believe that keeping just enough nutes to sustain, allows the maturation of all the good stuff.
My .02

Peace and Great Grows

Asmallvoice

I flush periodically with PH adjusted water when it feels 'about time'. Maybe it's superstition, or maybe I'm breaking down and removing mineral salts building up in the coco.

I have smoked plenty of non-flushed crappy weed, and plenty of tasty flavorful flushed-prior-to-harvest weed. Now - I'm not going to say the flavor difference is entirely down to flushing because I can't prove that, side by side comparison though I would take flushed produce every time.

Edit: it's not exactly an area of expertise so maybe someone can chime in but...one of the important reasons as I understand it to leech is that plants absorb both water and nutrients, but they don't absorb them necessarily at the same rate as a) you're feeding them and b) the plant next to them.

What this effectively means is say the plant takes x amount of nitrogen, x amount of magnesium, but has plenty of mineral soandso and leaves it in the coco. Next feed time same thing happens more mineral soandso builds up ("mineral salts").

The salts can stop the plant from taking in any nutrients and once the nute deficiency shows you can either flush and start the schedule over or keep feeding it and kill the plant.

So basically it's that different plants take up different types and amounts of nutes depending on their situation, this is why in anything using a resevoir you need to keep checking the PH levels - because if an imbalance occurs the PH level will vary wildly and cause all sorts of further nutrient uptake issues etc.

Also, what the OP says about cure is somewhat true - a lot of flavor and appeal is brought out during a proper cure (which so many neglect or rush) but I'm still unconvinced about the issue of flushing being of no value (prior to harvest). Maybe it's because it seems logical to me - we're essentially feeding these plans a regime of nutrients to force them into high growth in simulated conditions - it's somewhat useless worrying about what's 'natural' or otherwise in such a setting.

AltDog said:

I flush periodically with PH adjusted water when it feels 'about time'. Maybe it's superstition, or maybe I'm breaking down and removing mineral salts building up in the coco.

I have smoked plenty of non-flushed crappy weed, and plenty of tasty flavorful flushed-prior-to-harvest weed. Now - I'm not going to say the flavor difference is entirely down to flushing because I can't prove that, side by side comparison though I would take flushed produce every time.

Edit: it's not exactly an area of expertise so maybe someone can chime in but...one of the important reasons as I understand it to leech is that plants absorb both water and nutrients, but they don't absorb them necessarily at the same rate as a) you're feeding them and b) the plant next to them.

What this effectively means is say the plant takes x amount of nitrogen, x amount of magnesium, but has plenty of mineral soandso and leaves it in the coco. Next feed time same thing happens more mineral soandso builds up ("mineral salts").

The salts can stop the plant from taking in any nutrients and once the nute deficiency shows you can either flush and start the schedule over or keep feeding it and kill the plant.

So basically it's that different plants take up different types and amounts of nutes depending on their situation, this is why in anything using a resevoir you need to keep checking the PH levels - because if an imbalance occurs the PH level will vary wildly and cause all sorts of further nutrient uptake issues etc.

Also, what the OP says about cure is somewhat true - a lot of flavor and appeal is brought out during a proper cure (which so many neglect or rush) but I'm still unconvinced about the issue of flushing being of no value (prior to harvest). Maybe it's because it seems logical to me - we're essentially feeding these plans a regime of nutrients to force them into high growth in simulated conditions - it's somewhat useless worrying about what's 'natural' or otherwise in such a setting.

Click to expand...

I can see the point in all that up to the last sentence, and there, you lose me. We are growing plants, not lego blocks. All natural in its entirety. So that must be factored in at all times, or straight way to "crappy" weed you go. We may feed in many different ways, but the plants only do right when things are right.
I am a firm believer in cutting back at the end and doing weekly flushes. My weekly flushes are just an extended feed time at the current level nutes, I do not alter the food, just run a bunch through once a week.
The only thing unnatural about feeding is trying to make a plant that is at the end of it's cycle and treat it as if it were still thriving and feeding it as such. From what I have researched, not pulling back on the nutes brings more heartache than good and almost always imparts an undesirable taste even with a "perfect"cure.

Peace and Great Grows

Asmallvoice

Many people would argue that taking a plant out of soil and growing it indoors where it never sees the sun as the very definition of 'unnatural', regardless of flushing etc. We're attempting to EXCEED the potential natural conditions, to be "better" than a plant grown outdoors in soil with no added ferts or attention other than that given by the rain, and let go to seed (that's 'natural').
So I guess my point, which was pretty unrelated to anything, was that I think plants can be 'healthy' while not being grown 'naturally'.

I stopped flushing in any medium last year and never looked back. I believe it was one of Heisenbergs post on the subject that changed my perspective. I dry and cure properly with a controlled environment/hygrometers and will take the pepsi challenge any day for flavor. I feed 900+ ppm until chop.

I've never completely bought into the flushing thing and tend to skip over the sometimes passionate exchanges on the subject....
Still, its nice to read some of the reasonable arguments for and against and the replies from the more intelligent members of the forum

JohnnySocko said:

I've never completely bought into the flushing thing and tend to skip over the sometimes passionate exchanges on the subject....
Still, its nice to read some of the reasonable arguments for and against and the replies from the more intelligent members of the forum

Click to expand...

I take everything I read with a grain of salt, so I decided to do my own test. Same strain, same medium, same nutes. One was flushed for 2 weeks and one wasn't. Mr flush yielded 10 grams less and tasted exactly the same as Mr non-flush. While Mr flush was yellowing and dying Mr non-flush was happy as a lark and swelled a bit more. I am a FIRM believer now that the dry/cure is the defining factor in taste. I don't preach it or tell others they are stupid for flushing though. To each his own.

Bucees said:

I take everything I read with a grain of salt, so I decided to do my own test. Same strain, same medium, same nutes. One was flushed for 2 weeks and one wasn't. Mr flush yielded 10 grams less and tasted exactly the same as Mr non-flush. While Mr flush was yellowing and dying Mr non-flush was happy as a lark and swelled a bit more. I am a FIRM believer now that the dry/cure is the defining factor in taste. I don't preach it or tell others they are stupid for flushing though. To each his own.

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Dig that...and yeah similarly...
I was/am (SHORTLY) on a mini crusade against those that think removing chlorine from tap water has some sort of benefit...
This "crusade" was brought on by a thread where I noticed some posters were using Dutchmasters zone, OR Peroxide or even bleach yet still mindlessly aerated their res's or waited 24hrs to remove the tap waters chlorine ...
(if the dichotomy or pointlessness of de-chlorinating tap water then later adding a oxidant anyway escapes you, then brush up on your chemistry a lil)

Anyway.... I digress (pardon the thread deviation)
I then realized I/we/us very often simply read some shit on the internet then follow it like f^ckin automatons w/o giving it any thought or doing controlled experiments like you did...

...flush or not? I dunno, perhaps a waste, or not... but apparently to those that do it, its not that much bother, placebo or whatever.....

Before I popped my first seed, I was already skeptical on the whole " no nutes " for the last week or so of life.

Farmers and any other type of gardeners do not participate in such a practice. Flushing to me is simply that, flushing the medium with enough of the current level nutrients to " drag " the wee bit of junk that can build up over time out of the medium. I do drop the level of nutes down to about 35% for the last week, but they still have all the available nutrients, just not at full power. (1100ppm down to 350-390ppm)

I have had virtually no leaf drop or discoloration on the day of the chop. I do a long slow dry in my cure cabinet, slowly stepping the humidity down and I love the way the smell and taste develop over time. The slower the dry/cure the better....imo

Peace and Great Grows

Asmallvoice

I use plagrom baged coco me and a frend never wash it but i flushet often and every time there is brown somtimes dark brown water coming dovn the botom does somebody know what is that .... and every grow i have some litle problems but the was yeikld is ok

Can sombody tell me if i feed ph 5.6 ppm 700 (1.4ec) temp 21 degre celsius but the run of is from 6.5 to 6.8 ph ppm 220 to280 and temp 24 the first time i watered 5.8ph and the run of was 5.8 is that ok i check every plant i want to know what i am doing rong

JohnnySocko said:

Dig that...and yeah similarly...
I was/am (SHORTLY) on a mini crusade against those that think removing chlorine from tap water has some sort of benefit...
This "crusade" was brought on by a thread where I noticed some posters were using Dutchmasters zone, OR Peroxide or even bleach yet still mindlessly aerated their res's or waited 24hrs to remove the tap waters chlorine ...
(if the dichotomy or pointlessness of de-chlorinating tap water then later adding a oxidant anyway escapes you, then brush up on your chemistry a lil)

Anyway.... I digress (pardon the thread deviation)
I then realized I/we/us very often simply read some shit on the internet then follow it like f^ckin automatons w/o giving it any thought or doing controlled experiments like you did...

...flush or not? I dunno, perhaps a waste, or not... but apparently to those that do it, its not that much bother, placebo or whatever.....

Click to expand...

Oh to hell with thread deviation. There is knowledge to spread!

I originally aired out my water too. I mean I read it all over the place, and even in the more popular grow books. After reading some insightful information (science) on the subject I saw how absolutely pointless it was. Hell I even skip bennies in my res anymore and straight chlorinate it back to tap ppm's. Plants grow just fine and the chlorinated water keeps it nice and sterile in there. I have also done side by side test using bennies in one res and the B word in the other. I saw no problems in either one. I never suggest this kind of thing though because I don't want to start a argument in some poor schlubs thread.