Final Flush: Myth Or Fact?

[Drivejunky95]

Have you noticed a difference in taste of smoke having tried buds from final flushed / unflushed plants? (Same strain pref)

If not much of a difference... could there be health reasons for flushing synthetic nutrients out vs organic?

 

[Blew Hiller]

Check out @InTheShed threads...they discuss flushing there.

 

[InTheShed]

Thanks Blew!

@Drivejunky95, I have a link in my signature to a scientific analysis on preharvest flushing.
Here it is:

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...

www.420magazine.com

Flowers do not uptake nutrients from the soil, whether synthetic or organic. The plant takes up the nutrients and converts them into sugars to build the buds.

It's the dry and the cure that preserves the flower smell and taste and rids the buds of harshness.

Huge arguments have gone on over this, but more and more growers are coming to the conclusion that flushing is bro-science.

Keep in mind that you should do whatever you feel good about, but I feel there is no reason to starve a plant just when you want it to power its way to the finish line.

Note: this does not apply to flushing to correct soil imbalances! Just the alleged "cleaning the nutes from the buds before chop" flushing .

 

[Drivejunky95]

Oh.. no way.. I've read the 'do we need to ph our nutrient solutions' thread and do believe it's all about the CEC... looking forward to reading.. glad I asked!

 

[InTheShed]

Some folks have started jumping on that thread recently...they are very upset that I post that link and they feel the need to refute it. Read it all with a critical eye.

 

[Conradino23]

“Bro science”

Yep that’s exactly what it is! If you find me one scientific peer reviewed study of flushing in cannabis cultivation then I’m gonna sponsor your weed consumption till the end of your life

 

[Chris Scorpio]

I don't flush

Done and done

 

[MrFortwenty]

Total stoner science. But beware, you're going to get some in here that say science doesn't matter and their own "experiments" show otherwise lol

Irrigation Management Strategies for Medical Cannabis in Controlled Environments

The effects of flushing were also investigated to determine whether it had the intended effect of reducing nutrient concentrations within the dried bud. Through the use of psychrometers, water status (cWP) thresholds were correlated with humidity (cVPD) thresholds and reduced irrigation frequency resulting in water use reductions up to 45.7% which had negligible impacts on yield and cannabinoid profile. Flushing was found to be ineffective in removing any significant amount of nutrient from the bud.

Section 6.2

The practice of flushing is a current common industry practice but there is no evidence in published literature of its effectiveness in reducing nutrient concentrations within the bud or even whether or not this is a desirable result. After testing the nutrient concentrations from each treatment from three separate experiments, there were no significant differences in nutrient levels between any treatments within each experiment. This result showed that the intended purpose of flushing to reduce nutrient concentrations within the bud has no effect. These data show that for the last two weeks of the flower cycle for cannabis, it was possible to use no fertilizer water for irrigation with no significant impact on yield while saving input costs on fertilizer.

 

[Drivejunky95]

Nice! It sounds like you are potentially cutting yourself short on total bud weight too even.

No concrete evidence... larger buds... hmmmm.

 

[MrFortwenty]

Nice! It sounds like you are potentially cutting yourself short on total bud weight too even.

No concrete evidence... larger buds... hmmmm.

Umm...not quite

"for the last two weeks of the flower cycle for cannabis, it was possible to use no fertilizer water for irrigation with no significant impact on yield while saving input costs on fertilizer. "

 

[Drivejunky95]

Umm...not quite

"for the last two weeks of the flower cycle for cannabis, it was possible to use no fertilizer water for irrigation with no significant impact on yield while saving input costs on fertilizer. "

True, but in contrast, flushing, which stresses the plant and leaves only mobile nutrients available slowing development processes, I'd think you'd want some fertilizer.

The medium probably has enough to supplement during the final weeks. But flushing everything out... nah.

Says it didnt negatively impact yields, doesnt say continuing to feed will positively effect them

 

[MrFortwenty]

True, but in contrast, flushing, which stresses the plant and leaves only mobile nutrients available slowing development processes, I'd think you'd want some fertilizer.

The medium probably has enough to supplement during the final weeks. But flushing everything out... nah.

Says it didnt negatively impact yields, doesnt say continuing to feed will positively effect them

You're not "flushing" as in running a ton of water through the plant like you would for a toxicity issue. You're just watering with no nutes. Read the study lol

 

[Drivejunky95]

You're not "flushing" as in running a ton of water through the plant like you would for a toxicity issue. You're just watering with no nutes. Read the study lol

Soil would be different than coco, I think. Unless you dont water for 2 weeks...

 

[Conradino23]

Total stoner science. But beware, you're going to get some in here that say science doesn't matter and their own "experiments" show otherwise lol

Irrigation Management Strategies for Medical Cannabis in Controlled Environments

The effects of flushing were also investigated to determine whether it had the intended effect of reducing nutrient concentrations within the dried bud. Through the use of psychrometers, water status (cWP) thresholds were correlated with humidity (cVPD) thresholds and reduced irrigation frequency resulting in water use reductions up to 45.7% which had negligible impacts on yield and cannabinoid profile. Flushing was found to be ineffective in removing any significant amount of nutrient from the bud.

Section 6.2

The practice of flushing is a current common industry practice but there is no evidence in published literature of its effectiveness in reducing nutrient concentrations within the bud or even whether or not this is a desirable result. After testing the nutrient concentrations from each treatment from three separate experiments, there were no significant differences in nutrient levels between any treatments within each experiment. This result showed that the intended purpose of flushing to reduce nutrient concentrations within the bud has no effect. These data show that for the last two weeks of the flower cycle for cannabis, it was possible to use no fertilizer water for irrigation with no significant impact on yield while saving input costs on fertilizer.

Thx for that, man.

I mean it’d be absurd to find otherwise. The stoner belief, which I call magic belief, cause that’s what it is... and I don’t have anything against magic, cause if used properly it will help for sure , but growth of a plant is based on biology and interaction with the environment and we get into certain rules such as there’s no reverse osmosis in cannabis, so there just CAN’T BE giving back nutrients to the soil or whatever they call it... I also found shitloads of different interpretations. Some guys were claiming that the plunt flushes herself or something like that or that she consumes the leftovers... here I always come with a question, why does she even have leftovers? WTF does it even mean? So the logic is to pump her to an OD and then bring her back? How crazy is that?

 

[Conradino23]

Soil would be different than coco, I think. Unless you dont water for 2 weeks...

Yes it would be and we have a parameters for that, which are called CEC and AEC. The higher the 1st one the more difficult it becomes to flush out most of the cations, but if you just wanna get rid of nitrogen it can be done? But then why would you do it if buds are composed mostly of nitrogen?

 

[Carcass]

I've never flushed anything but the toilet.
I don't do it because I don't think it does anything beneficial.
My plants,my science.

Flushing is fine for those who do it,I'm just one that doesn't.
They're your plants,so do what you think is required for a good harvest.

 

[Drivejunky95]

Yes it would be and we have a parameters for that, which are called CEC and AEC. The higher the 1st one the more difficult it becomes to flush out most of the cations, but if you just wanna get rid of nitrogen it can be done? But then why would you do it if buds are composed mostly of nitrogen?

Think everything's that's been said is correct.

In coco running plain water (RO) would move the nutrients down to the bottom, which would have a flushing effect.

After 2 weeks of that may as well be flushing, haha.

But in soil for final 2 weeks plain RO water would work, I think.

Either case, it's probably to the plants' benefit to keep pumping it with nutes to the very end. Feeding unfertilized water doesnt sound like it negatively effects yields, but continuing to feed the plant crosses the finish line with flying colors... I'd think.

 

[HigherTheHigh]

If you use synthetic nutes i would flush for at least 2 weeks no matter what the medium, iv been growing in coco for nearly 3 years and tasting unflushed bud is the worst taste in the world, anyone that thinks different must not be human.

Im now in soil and im in the last 2 weeks using just water and molasses, like i would in coco.

 

[MrFortwenty]

If you use synthetic nutes i would flush for at least 2 weeks no matter what the medium, iv been growing in coco for nearly 3 years and tasting unflushed bud is the worst taste in the world, anyone that thinks different must not be human.

Im now in soil and im in the last 2 weeks using just water and molasses, like i would in coco.

So...ignore the actual science that says you're flushing nothing from your buds?

 

[HigherTheHigh]

Iv learnt by not flushing when using synthetic nutes leaves a disgusting taste and bud that doesnt burn.