Liquid flush?

[Charmanderrr]

So I was wondering if it’s worth buying the liquid flushes that some companies sell or if it’s a scam product. Is it really necessary to add something to flush the plant? If I’m using liquid ferts can’t I just stop the feeding a few in advance to harvest? Lately I’ve heard controversies over whether or not flushing is even necessary, similar to the dispute over dark time before harvest. Let me hear your feedback, it would be appreciated. By me.

 

[Phytoplankton]

A before harvest flush has been scientifically shown to be largely ineffective. A flush because of nute lock or nute toxicity has valid value. As far as dark time, it does seem to increase terpine production, and 48-72 hours of dark prior to harvest also forces the plant to use up any stored sugars or carbohydrates. Sugars/carbs tend to make the smoke harsher. IMHO

 

[Regrowth]

I think the premise is that the liquid could help dislodge the salts with less water having to be ran through the medium. I can't confirm but I think I read that some are just h2o2 based so might not even be worth the purchase. And if you're running h2o2 through your soil it usually has an impact on beneficial microbes so if you could just run more water through to flush it's preferable. Also agree with the note above about only flushing to fix lockouts or to reset

 

[bluter]

I think the premise is that the liquid could help dislodge the salts with less water having to be ran through the medium. I can't confirm but I think I read that some are just h2o2 based so might not even be worth the purchase. And if you're running h2o2 through your soil it usually has an impact on beneficial microbes so if you could just run more water through to flush it's preferable. Also agree with the note above about only flushing to fix lockouts or to reset

you can run h2o2 constant at a low level all through the grow with salt based nutes on hydro rules. the microbes don't do well on any salt chelated nute anyway.

if you're dwc or rdwc you can run it constant sterile. ofc it'll mess up a live res, but so will a lot of live cleaners. that's the job.

i do passive hydro and only use it if i need to fix an issue with a flush now.

i have a different nute, but when i ran AN bottled nutes a regular flush with h2o2 was part of the program a minimum three times through the grow. two in veg and one part way through flower. kept stuff good, clean, and in order. go without ... ph and lockout shit ensued. a lot of that is up to AN, but there's piles of nutes go the same.

i ran a fffw sched with amendments on the water side if i did any. everything always religiously ph'd. worked a beaut. the water side is important. but a periodic flush with h2o2 always launched a surge.

it only applies to salt based bottled nutes. there are others out there.

 

[Charmanderrr]

Thank you guys! Answers a lot of questions but also raises more. What extent are flushes unecessary? I always assumed fertilizing without flushing lead to trace minerals being left behind that’ll snap crackle and pop when you put a flame to it. Is that true? I guess I’m wondering what the lab study was and what it’s analysis was to it.

 

[Regrowth]

@InTheShed is a good person to ask. Hope he doesn't mind me tagging him.

 

[InTheShed]

@InTheShed is a good person to ask. Hope he doesn't mind me tagging him.

Thanks for the tag Regrowth! I'm pretty much in agreement with Phyto below ↓

A before harvest flush has been scientifically shown to be largely ineffective. A flush because of nute lock or nute toxicity has valid value.

Feeding plain water for the last x days before harvest produces no changes in the nutrient levels in the flowers at harvest according to the scientific studies done (top links in my sig). Flowers are nutrient sinks, not sources. The plant doesn't go to the buds to find needed elements when it can't get them from the roots.

I do wonder about this though:

As far as dark time, it does seem to increase terpine production

If you lock your plants in a dark area for 48 hours it's going to smell much more dank than if you open the door to check on them every 12 hours, so I wonder how that variable plays into it. Same is true with smelly bathrooms.

 

[Braddah Waiheesohai]

The liquid flush products have compounds in them that bond to the built up salts in your soil and help remove more built up salts than just water alone.

Make sure and read the label, some of them may contain some nutes as well.

The majority on this site are strongly against doing a 'flush' before harvest. Without getting into that debate, most nute companies push the pre harvest flush because there isn't enough benefit feeding the last week to outweigh the cost of continuing to feed a plant you're about to chop down.

I reduce feeding at the end my grows as part of an attempt to signal to my plants that their time is ending and they need to get busy producing resin and terpenes to protect themselves and try and reproduce, but many on here will strongly argue against that as well.

Flushing should be done in cases of nute lockout to clear the medium of built up salts. Most feeding plans include a just water feed (i.e. feed, water, feed, water) to help prevent this from becoming an issue in the first place.

The whole flushing at the end to remove nutrients from the plants is mis-understood information that has been proliferated online and gotten even sillier since about 2001 when medical and rec really started taking off and kooks started rushing into the business looking for a quick buck.

 

[Braddah Waiheesohai]

Thanks for the tag Regrowth! I'm pretty much in agreement with Phyto below ↓

Feeding plain water for the last x days before harvest produces no changes in the nutrient levels in the flowers at harvest according to the scientific studies done (top links in my sig). Flowers are nutrient sinks, not sources. The plant doesn't go to the buds to find needed elements when it can't get them from the roots.

I do wonder about this though:

If you lock your plants in a dark area for 48 hours it's going to smell much more dank than if you open the door to check on them every 12 hours, so I wonder how that variable plays into it. Same is true with smelly bathrooms.

Dark period alters the terpene profile (i.e. changes the ratio of terpenes present), I'll try and find the studies again, but only increases production in about 20% of plants.

 

[InTheShed]

I'll try and find the studies again

Looking forward to it! Interesting that it only works on 20% of the varieties. I wonder what the determining factor is...dominant terpene profile?

 

[Charmanderrr]

Looking forward to it! Interesting that it only works on 20% of the varieties. I wonder what the determining factor is...dominant terpene profile?

I wonder if it’s actually particular environmental conditions that act as the trigger.

 

[Braddah Waiheesohai]

If I remember right it was more like 20% of plants, so it was pheno specific as well as strain specific. All the plants in the study were grown in the same environment so in this case, the trigger wasn't necessarily environmental (aside from the darkness).

 

[Braddah Waiheesohai]

Still sifting through all the garbage trying to find the study again. I know it wasn't the infamous Stichting Institute of Medical marijuana (SIMM) study, though that is an interesting read.

Really though all the current info says that up to about 48 hours of darkness won't hurt your harvest, and may help increase terpenes, and THC, but likely won't effect CBD levels. So it's just a question of whether or not you have the time / inclination to give it a try.

As it seems to be pheno specific (which would account for all the mixed reports in forums etc about its efficacy) it may be worth testing/noting when doing a pheno hunt for your future grows.


*Unrelated science that may be of interest:

Geeking out on trichomes:

Error - Cookies Turned Off

onlinelibrary.wiley.com

sub canopy lighting increasing yields by 19-24%:

Improving Cannabis Bud Quality and Yield with Subcanopy Lighting

The influence of light spectral quality on cannabis (Cannabis sativa L.) development is not well defined. It stands to reason that tailoring light quality to the specific needs of cannabis may increase bud quality, consistency, and yield. In this study, C. sativa L. ‘WP:Med (Wappa)’ plants were...

journals.ashs.org

deep dive on drying practices:

https://dalspace.library.dal.ca/bitstream/handle/10222/80480/Challa-Saikiran-MSc-Agri-March-2020.pdf?sequence=1&isAllowed=y

 

[InTheShed]

Still sifting through all the garbage trying to find the study again. I know it wasn't the infamous Stichting Institute of Medical marijuana (SIMM) study, though that is an interesting read.

Really though all the current info says that up to about 48 hours of darkness won't hurt your harvest, and may help increase terpenes, and THC, but likely won't effect CBD levels. So it's just a question of whether or not you have the time / inclination to give it a try.

As it seems to be pheno specific (which would account for all the mixed reports in forums etc about its efficacy) it may be worth testing/noting when doing a pheno hunt for your future grows.


*Unrelated science that may be of interest:

Geeking out on trichomes:

Error - Cookies Turned Off

onlinelibrary.wiley.com

sub canopy lighting increasing yields by 19-24%:

Improving Cannabis Bud Quality and Yield with Subcanopy Lighting

The influence of light spectral quality on cannabis (Cannabis sativa L.) development is not well defined. It stands to reason that tailoring light quality to the specific needs of cannabis may increase bud quality, consistency, and yield. In this study, C. sativa L. ‘WP:Med (Wappa)’ plants were...

journals.ashs.org

deep dive on drying practices:

https://dalspace.library.dal.ca/bitstream/handle/10222/80480/Challa-Saikiran-MSc-Agri-March-2020.pdf?sequence=1&isAllowed=y

First link was over my head and the last one didn't resolve, but the underlighting one was interesting because it seems like they boosted the total PPFD without burning the tops by splitting the light sources. Did I read that right?

 

[bluter]

The liquid flush products have compounds in them that bond to the built up salts in your soil and help remove more built up salts than just water alone.

that's just marketing. the majority of the flushing agents out there are just throwing overpriced h2o2 under another name at your plants. sometimes they'll huck other crap in there to try make you feel better.

The majority on this site are strongly against doing a 'flush' before harvest. Without getting into that debate, most nute companies push the pre harvest flush because there isn't enough benefit feeding the last week to outweigh the cost of continuing to feed a plant you're about to chop down.

and they get to sell you overpriced unneeded "flushing agents" to do an unneeded job.

I reduce feeding at the end my grows as part of an attempt to signal to my plants that their time is ending and they need to get busy producing resin and terpenes to protect themselves and try and reproduce, but many on here will strongly argue against that as well.

they would be mostly correct.

Flushing should be done in cases of nute lockout to clear the medium of built up salts. Most feeding plans include a just water feed (i.e. feed, water, feed, water) to help prevent this from becoming an issue in the first place.

that's more like it

The whole flushing at the end to remove nutrients from the plants is mis-understood information that has been proliferated online and gotten even sillier since about 2001 when medical and rec really started taking off and kooks started rushing into the business looking for a quick buck.

it started in hydro and got out of control. it all began in the 80's when hydro shops started popping up all over. the nutes where different back then. there was greater salt build up. it was standard practice to teach the shop clerks to recommend it.

i first ran in to it when i worked at the hydro shop in 82. the nute guys were looking for a way to sell more product.

 

[InTheShed]

that's more like it

 

[Braddah Waiheesohai]

that's just marketing. the majority of the flushing agents out there are just throwing overpriced h2o2 under another name at your plants. sometimes they'll huck other crap in there to try make you feel better.






and they get to sell you overpriced unneeded "flushing agents" to do an unneeded job.







they would be mostly correct.



that's more like it






it started in hydro and got out of control. it all began in the 80's when hydro shops started popping up all over. the nutes where different back then. there was greater salt build up. it was standard practice to teach the shop clerks to recommend it.

i first ran in to it when i worked at the hydro shop in 82. the nute guys were looking for a way to sell more product.

Everyone's an expert and no-one agrees . Read up and make up your own mind.

If someone told me 30 years ago when I had a few thousand square feet of plants indoors and many acres outdoors we'd be arguing about 'flushing' on the internet I prolly would have fallen out of my chair laughing.

 

[bluter]

If someone told me 30 years ago when I had a few thousand square feet of plants indoors and many acres outdoors we'd be arguing about 'flushing' on the internet I prolly would have fallen out of my chair laughing.

need one big hose for that outdoor flush ..

 

[Braddah Waiheesohai]

Can you imagine feeding acres of outdoor in a guerilla environment with bottle nutes ? That's one of my fav weedforum reductio ad absurdums.

 

[bluter]

Can you imagine feeding acres of outdoor in a guerilla environment with bottle nutes ? That's one of my fav weedforum reductio ad absurdums.

yeah but if you got a nickel deposit on each bottle you'd be worth millions man ..