Flushing: The Myth that won't Die

[DankDoctor420]

Never mind my last question. After reading more and more pages I found my answer. I will never worry about flushing or giving plain water at the end of my grows anymore. I believe you all and don't think that many people would lie to me. It just sounded really crazy at first cuz it went against everything I had learned and I was like what? But after reading people's testimony that they stopped flushing and notice no difference in the final product if it's dried and cured right feeding to the end. Thanks for breaking my old way of thinking @pop22 and everyone else who shared there experiences. I will convert if I go back to feeding nutes daily but I'm really digging the grow dots so far. I'm @ week 10 into my current 12 plant auto grow. Gonna be harvesting some in the next week or two then the rest 2 weeks later after those dry. From now on if I go back to powder or bottle nutes which I have both laying around I will discontinue the flush or plain water the last two weeks. I wont starve my plants no more

 

[Zaaboot]

The first time I grew many moons ago I Flushed - It was in an NFT tray, by the end the leaves had yellowed etc… I read a lot about the root systems and general plant biology and thought it was bollocks, either way I stopped flushing them and have never looked back.
I cannot for the life of me understand why you’ll starve the bejeezus out of a living thing hoping it makes it better

Z

 

[Son of Hobbes]

Whenever I used synthetic or chelated nutrients I always watered only the last two weeks in soil cuz that is what I was taught on the web. I'm using grow dots now so I can't flush this run as it's water only. No mixing up nutes. Is watering like normal but with no nutes only the last two weeks ok without heavily flushing the soil? Or is it just not gonna matter in the final product if you feed to the finish line and don't water only til the end? There is a lot of mixed reviews in this thread. Should people use water only the last two weeks still or is that not necessary, it's just ok to feed right up til the chop?

"Harvest flushing" is simply cutting all nutrients and only giving the plants water for a specified amount of days. The more appropriate term should (in my humble opinion) be "leeching," as it's the process of moving/removing water soluble nutrients from the medium (not from the plant itself though, which is what the pro-flush camp insists is happening.)

If you're using synthetic nutrients, much of this can be achieved throughout the grow by simply incorporating regular plain waterings into your schedule, and watering until runoff (helps to remove leftover and residual salts from the medium.)

Here's my personal experience; at one of the last farms I worked for, we started out flushing our plants (plain water a week or two) before harvest, then towards the end of that gig, the grow QUIT flushing altogether. What we saw was INCREASED yields, absolutely noticeable gains, from feeding all the way up to chop. And compared to historical data for the same cultivars grown (in rotation) for the same time of year. With absolutely zero negative effect on the quality of the flower.

I calculated our nutrient cost for not giving nutrients that one week to the finishing plants; it saved the grow about $110/week or so. That's not including time and labor costs, just material.

$400+/month could have paid a few hands to defoliate, prune, etc, which arguably could have helped some plants produce more weight as well.

So there is some merit on both sides of the coin I think; it's just that science doesn't really back up the act of flushing out your plants, at least not at the face value that growers, for whatever reason, just blindly took on good faith was true (with nothing to substantiate it other than anecdotal evidence. "I see and I think, therefore it must be true.")

That's probably the biggest elephant in the room; is that there is just little to no credible science that actually supports harvest flushing pot. I've yet to this day, out of all the cannabis educators, researchers, growers, commercial growers, etc, have found ANYONE that can explain to me on a scientific level what flushing cannabis is doing pre-chop. And that's a bit of a red flag when everyone is preaching it, but no one can explain it.

 

[CannabisMingus]

That's probably the biggest elephant in the room; is that there is just little to no credible science that actually supports harvest flushing pot.

 

[pop22]

I can see the commercial application, IF the gain in weight does not outweigh the cost to feed another week. Knowing what many ops feed at, reducing ppm to the 400-500 ppm range would alter that senario possibly enough to make it worth it. I suspect that plants feed less in the final stages to the point that the residuals in the medium and the lower ppm solution would be enough to carry them at least a week. If you gained only 6 grams per plant, thats a pound and a quarter per 100 plants.

"Harvest flushing" is simply cutting all nutrients and only giving the plants water for a specified amount of days. The more appropriate term should (in my humble opinion) be "leeching," as it's the process of moving/removing water soluble nutrients from the medium (not from the plant itself though, which is what the pro-flush camp insists is happening.)

If you're using synthetic nutrients, much of this can be achieved throughout the grow by simply incorporating regular plain waterings into your schedule, and watering until runoff (helps to remove leftover and residual salts from the medium.)

Here's my personal experience; at one of the last farms I worked for, we started out flushing our plants (plain water a week or two) before harvest, then towards the end of that gig, the grow QUIT flushing altogether. What we saw was INCREASED yields, absolutely noticeable gains, from feeding all the way up to chop. And compared to historical data for the same cultivars grown (in rotation) for the same time of year. With absolutely zero negative effect on the quality of the flower.

I calculated our nutrient cost for not giving nutrients that one week to the finishing plants; it saved the grow about $110/week or so. That's not including time and labor costs, just material.

$400+/month could have paid a few hands to defoliate, prune, etc, which arguably could have helped some plants produce more weight as well.

So there is some merit on both sides of the coin I think; it's just that science doesn't really back up the act of flushing out your plants, at least not at the face value that growers, for whatever reason, just blindly took on good faith was true (with nothing to substantiate it other than anecdotal evidence. "I see and I think, therefore it must be true.")

That's probably the biggest elephant in the room; is that there is just little to no credible science that actually supports harvest flushing pot. I've yet to this day, out of all the cannabis educators, researchers, growers, commercial growers, etc, have found ANYONE that can explain to me on a scientific level what flushing cannabis is doing pre-chop. And that's a bit of a red flag when everyone is preaching it, but no one can explain it.

 

[Egg]

"Harvest flushing" is simply cutting all nutrients and only giving the plants water for a specified amount of days. The more appropriate term should (in my humble opinion) be "leeching," as it's the process of moving/removing water soluble nutrients from the medium (not from the plant itself though, which is what the pro-flush camp insists is happening.)

If you're using synthetic nutrients, much of this can be achieved throughout the grow by simply incorporating regular plain waterings into your schedule, and watering until runoff (helps to remove leftover and residual salts from the medium.)

Here's my personal experience; at one of the last farms I worked for, we started out flushing our plants (plain water a week or two) before harvest, then towards the end of that gig, the grow QUIT flushing altogether. What we saw was INCREASED yields, absolutely noticeable gains, from feeding all the way up to chop. And compared to historical data for the same cultivars grown (in rotation) for the same time of year. With absolutely zero negative effect on the quality of the flower.

I calculated our nutrient cost for not giving nutrients that one week to the finishing plants; it saved the grow about $110/week or so. That's not including time and labor costs, just material.

$400+/month could have paid a few hands to defoliate, prune, etc, which arguably could have helped some plants produce more weight as well.

So there is some merit on both sides of the coin I think; it's just that science doesn't really back up the act of flushing out your plants, at least not at the face value that growers, for whatever reason, just blindly took on good faith was true (with nothing to substantiate it other than anecdotal evidence. "I see and I think, therefore it must be true.")

That's probably the biggest elephant in the room; is that there is just little to no credible science that actually supports harvest flushing pot. I've yet to this day, out of all the cannabis educators, researchers, growers, commercial growers, etc, have found ANYONE that can explain to me on a scientific level what flushing cannabis is doing pre-chop. And that's a bit of a red flag when everyone is preaching it, but no one can explain it.

I studied plantsmanship back in the mid 90's @ the Royal Botanic Gardens in Edinburgh and spent most of my time in their world famous library looking for books on cannabis, not to mention other ethno-botanical curiosities - and there were some! Unfortunately the legal status of the plant for the past decades has hindered (stopped) any scientific (refrenceable) research into any element of growth, or indeed harvest. If this was a (historically) commercially viable crop there would be untold numbers of papers regarding every stage of growth and also best practice..
That said this site, with a bit of wading, for me at least, seems to be striving for the truth when it comes to cultivation, as well as the collation of data for autos.

 

[JaxsoNL5]

"Harvest flushing" is simply cutting all nutrients and only giving the plants water for a specified amount of days. The more appropriate term should (in my humble opinion) be "leeching," as it's the process of moving/removing water soluble nutrients from the medium (not from the plant itself though, which is what the pro-flush camp insists is happening.)

If you're using synthetic nutrients, much of this can be achieved throughout the grow by simply incorporating regular plain waterings into your schedule, and watering until runoff (helps to remove leftover and residual salts from the medium.)

Here's my personal experience; at one of the last farms I worked for, we started out flushing our plants (plain water a week or two) before harvest, then towards the end of that gig, the grow QUIT flushing altogether. What we saw was INCREASED yields, absolutely noticeable gains, from feeding all the way up to chop. And compared to historical data for the same cultivars grown (in rotation) for the same time of year. With absolutely zero negative effect on the quality of the flower.

I calculated our nutrient cost for not giving nutrients that one week to the finishing plants; it saved the grow about $110/week or so. That's not including time and labor costs, just material.

$400+/month could have paid a few hands to defoliate, prune, etc, which arguably could have helped some plants produce more weight as well.

So there is some merit on both sides of the coin I think; it's just that science doesn't really back up the act of flushing out your plants, at least not at the face value that growers, for whatever reason, just blindly took on good faith was true (with nothing to substantiate it other than anecdotal evidence. "I see and I think, therefore it must be true.")

That's probably the biggest elephant in the room; is that there is just little to no credible science that actually supports harvest flushing pot. I've yet to this day, out of all the cannabis educators, researchers, growers, commercial growers, etc, have found ANYONE that can explain to me on a scientific level what flushing cannabis is doing pre-chop. And that's a bit of a red flag when everyone is preaching it, but no one can explain it.

I believe on a scientific level (and no, I’m not a plant biologist so this is a hypothesis) what happens is the plant will switch from mostly anabolic to catabolic pathways of metabolism. When nutrients are plentiful the plant will use those as precursors to synthesize larger complex molecules for growth and repair (anabolism), and require less breakdown of stored molecules for energy (catabolism)…even though catabolism and anabolism work simultaneously, if nutrients are plentiful then anabolic pathways would be favored with baseline catabolism to generate ATP and other “energy” molecules that are required for the anabolic pathways to proceed.

When you “harvest flush” and begin depleting nutrients from the medium the plant will begin to catabolize it’s nutrient storages. In this case, in flowering plants, this usually signals plant senescence which is tied to chlorophyll breakdown.

The whole logic from what I gathered, especially with synthetic nutes, was doing a flush would remove excess stored nutes and remove a synthetic “metallic” taste in the cured buds. But plants don’t store nutes in the form we apply to the medium. I think there was a blind study recently that did a “taste” test, so not the most scientific approach to the issue, but without the participants knowing what was what the “non-flushed” cannabis was preferred.

 

[GreenBean]

I've only ever "flushed" the last week or so to save on the nutrients. I have not noticed a huge difference in yield by feeding until the very end personally. But I have no objections to trying it again. I haven't noticed any quality, or taste, difference in feeding till the end, or "flushing" either. Like I said, I only do it to save on the nutes.

 

[JaxsoNL5]

I've only ever "flushed" the last week or so to save on the nutrients. I have not noticed a huge difference in yield by feeding until the very end personally. But I have no objections to trying it again. I haven't noticed any quality, or taste, difference in feeding till the end, or "flushing" either. Like I said, I only do it to save on the nutes.

RX Technologies did the blind flush trial, the non-flushed cannabis was preferred overall (this was a subjective taste test though) and there was no statistically significant difference in biomass or potency when flushing was used.

Flushing Trial - RX Technologies
(just Google those words if you want to read it but don’t like clicking links )

I cut nutes too early my last grow and went water only, plant took a week longer to finish (and still needed more) and without the nutes present my girl was looking rough towards the end. Would’ve preferred giving nutes longer and cutting only the last week (if that) like you @GreenBean.

 

[GreenBean]

RX Technologies did the blind flush trial, the non-flushed cannabis was preferred overall (this was a subjective taste test though) and there was no statistically significant difference in biomass or potency when flushing was used.

Flushing Trial - RX Technologies
(just Google those words if you want to read it but don’t like clicking links )

I cut nutes too early my last grow and went water only, plant took a week longer to finish (and still needed more) and without the nutes present my girl was looking rough towards the end. Would’ve preferred giving nutes longer and cutting only the last week (if that) like you @GreenBean.

I believe I read that study awhile back.

I’ve tried a number of things. But normally I can see that they’re a week out and just cut off the nutes. I figure I push them pretty hard. They’re probably thinking- thank god. This MF gonna let me die in peace!

once I cut off nutes and water for like 10 days. Just a Let’s see what happens! Thing. I have a friend who still talks about that weed to this day. He was in love with it.

I’ll keep the current Mendel going till the end and see if she plumps even more.