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A critical look at preharvest flushing

Sierra Cowboy

Well-Known Member
When trying to convince another person that your view on a particular subject that they hold an opposing view of is correct is akin to reasoning with a child. You can present your argument complete with documentation, first hand experience and anecdotal evidence. You can empathize and provide support for this person. But it always comes down to " Daddy needs a time-out".
Please add my name to the rolls of the "No-Flush Club" if you don't trust either science or logic the you my friend are a fool or more likely :blunt:Nice post thanks for the info.
 

bluter

Well-Known Member
there is a commercial cannabis operation about a mile from my parents place. i know some of the owners, and hope to get the opportunity to have a look through the place. this is one of the things i am going to ask about if i get the chance.
 

TheMadDabber

Member of the Month: Dec 2017 - Nug of the Month: June 2018
The legit cultivators I work with all flush... less nutrients in the buds doesn't mean the smoke isnt more harsh. Everyone is predicating their stance based on the an old wives tale that nutrients in the bud cause harsh smoke. Wrong. The degradation of proteins into amino acids is what makes smooth smoke. Flushing triggers a process within the plant causing it to happen while alive instead of having to wait for a cure. So industry standard is flush so you can have your product ready for market faster with similar quality....

Also aspects such as over watering and lockout can effect taste of buds a ton.

I know I'll never win this argument but that's why we do it. Saves time and money. That's enough for me
 

BAKIND

Well-Known Member
A nice melange of about 70% Hiydrow cured for 18 months, 15% Blueberry cured for 6 months and 15% Dark Devil cured 2 months. LOS no flush.
Taste kinda like a fresh orange with a lingering very sweet aftertaste especially in a vaporizer set to about 390.
Smooth as can be even in a joint, clean burning, very mellow.
If you want cannabis that taste like this then it needs to be nurtured from seed to stoned, allow the microbes to feed the plant exactly what it needs.
And then properly dry and cure.


1753875
wow! very impressive white ash for not flushing in hydro. i think this does it for me. Flushing is not necessary, not even in hydro
 

SQl2kGuy

Well-Known Member
What an interesting read! ... lots of different opinions and ideas ... exactly the way it is supposed to be here at 420.

For me ... I define flushing to mean watering with 3 times the amount of water as the pot size. (3 litres water for 1 litre of soil)


At this point, I am comfortable flushing my soil with pH 6.3 water about every 4 weeks to remove debris, salts and to avoid pH drift.

I am also comfortable doing a final flush on my soil two weeks before harvest ... and then it's power-on feeding with full-dose bloom nutes.


I am just starting coco ... and plan to flush with pH 5.8 water about every 4 weeks to remove debris and salts. I think if you are feeding with 20% run-off everyday ... you are likely not getting a buildup of salts or debris.



I believe flushing helps the growing medium and curing helps the taste of the buds.


Is there anyone who thinks that flushing actually hurts the plant or the medium?
 

Remystemple

Well-Known Member
What an interesting read! ... lots of different opinions and ideas ... exactly the way it is supposed to be here at 420.

For me ... I define flushing to mean watering with 3 times the amount of water as the pot size. (3 litres water for 1 litre of soil)


At this point, I am comfortable flushing my soil with pH 6.3 water about every 4 weeks to remove debris, salts and to avoid pH drift.

I am also comfortable doing a final flush on my soil two weeks before harvest ... and then it's power-on feeding with full-dose bloom nutes.


I am just starting coco ... and plan to flush with pH 5.8 water about every 4 weeks to remove debris and salts. I think if you are feeding with 20% run-off everyday ... you are likely not getting a buildup of salts or debris.



I believe flushing helps the growing medium and curing helps the taste of the buds.


Is there anyone who thinks that flushing actually hurts the plant or the medium?
iv'e been doing the weekly flush by just giving double the amount of feed solution and it's crazy how the plants thank me for it lol. my blueberry's must have shot up 2 inches over night after last flush.
 

Remystemple

Well-Known Member
i see in one of the grow journals a member posted a pic of a pre-internet book, with the pages on flushing procedure...

it was one of the uk guys i believe
I have an old book that i'm waiting on return from my friend. i haven't even looked through it yet but it's got hundreds of pages / small print and a crazy amount of info. your comment made me remember to message my buddy to get his ass in gear and return it lol.

now that it won't seem like greek to me i'm excited to have a read through. also wondering how old it is.
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
i see in one of the grow journals a member posted a pic of a pre-internet book, with the pages on flushing procedure...

it was one of the uk guys i believe
Is that the same old book that stated growers could get a really high ratio of female plants by feeding them a solution containing birth control pills?
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
I forget whether the author was Mel Frank, Jorge what'shisname, or that other guy who wrote cannabis cultivation books in the '70s, but a few minutes spent doing a web search would bring up copies of most of the books. There was some... entertaining misinformation in a lot of them (along with the usual basic common sense "how to grow plants" stuff, of course).

Some of the things, well... If it's not actively harmful, the grower manages to grow plants to harvest from the general information, so grower adds two plus two and comes up with a grilled cheese sandwich (so to speak), and that's how fanciful stuff ends up getting passed along from grower to grower until it's assumed to be true / useful / worth more than a bean burrito fart, lol. A guy swore up and down that I needed to put my wife's BCPs into my nutrient solution in the late 1990s :19:. He was open to suggestions, mind you - as long as they mirrored what he'd been told decades earlier by someone who heard it from... someone ;).

Last I heard from him, he'd started buying all his smoke from the West coast. Said there was something in the environment here that wouldn't let people grow decent cannabis. . . .
 

Remystemple

Well-Known Member
I forget whether the author was Mel Frank, Jorge what'shisname, or that other guy who wrote cannabis cultivation books in the '70s, but a few minutes spent doing a web search would bring up copies of most of the books. There was some... entertaining misinformation in a lot of them (along with the usual basic common sense "how to grow plants" stuff, of course).

Some of the things, well... If it's not actively harmful, the grower manages to grow plants to harvest from the general information, so grower adds two plus two and comes up with a grilled cheese sandwich (so to speak), and that's how fanciful stuff ends up getting passed along from grower to grower until it's assumed to be true / useful / worth more than a bean burrito fart, lol. A guy swore up and down that I needed to put my wife's BCPs into my nutrient solution in the late 1990s :19:. He was open to suggestions, mind you - as long as they mirrored what he'd been told decades earlier by someone who heard it from... someone ;).

Last I heard from him, he'd started buying all his smoke from the West coast. Said there was something in the environment here that wouldn't let people grow decent cannabis. . . .
that's funny. kinda like my buddy who messed up his 5 gallon bucket dwc grow because " she got rootbound". i'm not a hydro grower but that just sounded off to me.
 

bluter

Well-Known Member
a couple months ago i mentioned i knew folk in the commercial growing world. i wanted to follow up on their growing practices related to this topic and a couple other things. this is what i learned.

to begin : they do not comment. it's simply not in their interest. it isn't about trade secrets, it's more about managing their time. there are plenty of other information sources. then he answered my questions anyway lol.

tours : they do not allow general public tours of the facilities. even media (the reporting kind lol ) has to jump through a pile of hoops to get in. it's more about gov't rules than company policy.

media : they are using a promix type "soilless soil". same as over 90% of the growers here. this means they are on hydro principles and use salt based fertilizers. they bring media components in and mix them in house. essentially just inert soil and perlite. nothing fancy.

organics : they are exploring different media on a cost benefit basis. there was a plan to try an organic approach, with composting of waste plant material being part of the proposal. turns out this is outright illegal. any unused organic material has to be cataloged, weighed, and destroyed (incinerated). other organics are perfectly fine, but it is very difficult to do a closed loop organic grow with the current rules. they are exploring outdoor growing as it becomes legal, even that won't be 100% organic.

nutrients : salt based. everything is brought in and nutes are compiled in house. they do not purchase or use any pre-made nutrients. essentially they make their own mega crop. they use RO water. not sure how it is ph'd.


flushing : definitely. described as standard industry practice.

everything grows on a set schedule. there are set days when they flush. once between seedling and veg stages, once between veg and flower stages, and at harvest. harvest flush is described again as standard industry practice.

how they flush : the exact same way we would water. there is no pouring of water 3 or four times the bucket capacity to wash the media. it's more a withdrawal of nutes for a few days. they don't call it flushing. they have no term for it. the plants are just "on water". harvest flush is the exact same as between plant stages.

@TheMadDabber described why they harvest flush to a T.

it is both a cost saving function, and critical to the way it is cured.



harvest trim and cure : at harvest the plants are watered only for a few days and left standing. this starts the harvest/cure process. the plants are left standing until the media has begun to dry after the final water ( note water, not flush ). then they are cut and the buds loosely trimmed. the buds are immediately fed to a mechanical trimmer for final trim, and from there go on to drying racks for final dry and cure.

the final dry and cure takes place in a very controlled environment. it sounds like they only cure them a couple wks. after a dry, the buds are vacuum bagged for longer term storage, and i assume they may cure a bit in the bag. RH percentages are super important at this time. bagging at the wrong rh will promote mold etc, destroying the harvest. if one bag tests positive, all have to be destroyed.


important to note this is an industrial process. i wouldn't grow tomatoes the same as a commercial greenhouse. home practices generally result in better produce. this is merely how the industry approaches it.
 
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Remystemple

Well-Known Member
I find it hard to believe that as money hungry as corporate cannabis is that any of them flush.

i don't find that hard to believe. think about the savings over the course of a year in not giving nutes for the last few days of a massive operation. I'd say that the savings far outweigh any benefit of feeding right until the end.

but i would also imagine that is probably the only reason they do it. lets face it, whether you flush or don't flush at the end we still end up with nice buds and a great harvest. wouldn't be surprised to hear they dial back the lights for the last week also.
 

Elvin

Well-Known Member
I understand the concept of "flushing" in regards to inert growing mediums but how does one flush the nutrients away from the root zone when using soil that contains nutrients?
 

bluter

Well-Known Member
I find it hard to believe that as money hungry as corporate cannabis is that any of them flush.

every feed costs them a few thousand dollars, at just this one facility. there are several places they grow across the country.


i was more shocked to learn they can not compost left over organic material. stems, leaves, roots, etc all have to be documented and destroyed.


it is important to note they have botanists (horticulturists ?) and mineralogists on staff who advised on the growing methods. there is a well-known agriculture college in the province where they hire most of their growing professionals from.
 
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bluter

Well-Known Member
I understand the concept of "flushing" in regards to inert growing mediums but how does one flush the nutrients away from the root zone when using soil that contains nutrients?
apples and oranges.

flushing is not used in that context. nothing commercial is grown in that manner.
 

Elvin

Well-Known Member
apples and oranges.

flushing is not used in that context. nothing commercial is grown in that manner.
Sorry; I read the title not the thread.
If the discussion is on commercial operations the obvious answer is if the two methods produce a product that sells equally as well in your market, then the method that produces more quantity is the logical choice.
In any business, you provide what sells and then you try to reduce expenses while increasing output.
If your market wants it flushed and you will realize a higher return selling that product, then do it.
Market capitalism really is not hard.
 
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