Flushing debate

[marski420]

Hello farmers I have a question for you. Lately I have been seeing many growers say they don't flush their plants towards the end of harvest and say that flushing is nothing but "bro science".

I personally have always flushed and found great results but a lot of these newer growers are swearing by not flushing and claiming it doesn't do anything to better the taste / final smoke quality. I'm not of this mentality at all but would love to hear what everyone around here thinks.

 

[BigCube]

Well, where to start. I do it because I've always done it and if it works why bother giving nutes to a plant that doesn't need it? By flush I assume you are talking about giving the plant just water no nutrients for the last week or two of the plants life.

I dont know if there is any validity to it, I've just always done it and would probably keep doing it until a decent argument can be made against flushing.

What I do now works, if it is some how better not doing so I would definitely like to know.

 

[Aqua Man]

IMO in hydro you don't need to flush. You want to reduce feeding to the plants needs.

In soil flushing can be beneficial if needed. Unlike hydro you can't just lower the ppm in your soil. But by flushing it allows you to do so.

Big misconceptions: You cannot pull out excess nutrients that the plants have taken up. This is where the bro science reference comes in. It just doesn't work like that. Excessive nutrients taken up can effect the taste.

IMO hydro and soil if fed properly does not need to be flushed.

Soil may benefit from flushing if there are excessive nutrients or salt buildup in the soil. After stretch the plants require slightly different nutrient ratios and generally lower levels as the progress in flower. Flushing can help a soil grower control this but once a plant has taken up excess nutrients you cannot flush it out of the plant.

Just this scrubs opinion.

 

[Migrower]

I’m hearing similar chatter here and there. Also arguments about pk boosters and if they work and if so when. I sure would like to know these answered also considering my first harvest will be in a few weeks.

 

[Migrower]

I believe soil is where it would come into play yes. And to flush out excess salts so they are none that the plant can take up if it wanted to the last week or two. That would make sense as to having to much nitrogen still available to take up and the plant having that alfalfa like taste or smell. But no I do not believe you flush nutrients out of your plant. Just the soil so it cannot be taking up. I’m using a lot of salt based nutes (gh) so I bought a flushing agent. It was recommended since I’m using the salts instead of just water. Infact I heard that flushing with just water is not what flushing is. That that itself is a myth.

 

[Migrower]

I’ll know for sure in a few weeks if one or both are true I’ll leave the koolbloom dry out of one of my plants and not flush another. Although I’m not sure about that. Considering I’d have to not flush a plant I was pk boosting as to see if it really makes a difference. Not flushing the non pk boosted one don’t make so much sense. Ok rethink the situation.

 

[Dirtbag]

Anecdotal.. But I've always fed plain water for the last 10-14 days, every grow for the last 20 years and my pot always turns out clean, burns white ash and tastes great.

The last run I was reading a lot about this too so I decided to taper off near the end, but fed right to the last watering just to see if it really made a difference. My pot came out noticeably harsher, burned dark grey and keeps burning out. Flavour is somewhat masked and it tastes a bit chemmy. I am going back to flushing at the end.

 

[Aqua Man]

Anecdotal.. But I've always fed plain water for the last 10-14 days, every grow for the last 20 years and my pot always turns out clean, burns white ash and tastes great.

The last run I was reading a lot about this too so I decided to taper off near the end, but fed right to the last watering just to see if it really made a difference. My pot came out noticeably harsher, burned dark grey and keeps burning out. Flavour is somewhat masked and it tastes a bit chemmy. I am going back to flushing at the end.

Recently had a discussion and I was corrected on a statement I made. It had to do with dark period before chop and the starches. I'm wondering if it has to do with starving the plant of nutrients results in extremely reduced production of starches etc. That are know to cause some harshness. This is where the claims of 24 he dark period comes into play.

I can't help but be curious if this is linked. And if you are starving them the last week there would be no need or little need for a longer dark period at chop and vice versa if you feed all the way a longer dark period would/could reduce that harshness you are referring to but also allow optimal growth of buds.

 

[MIMedGrower]

Well a couple of years ago i ran 3 sets of known dialed in cuttings 3 times each test to compare all the forum stuff I read.

To note i grow in potting soil and err on the side of underfeeding so it is not usually necessary for me to leach pots to clear out salts often. I believe heavy feeders may benefit from water only last 2 weeks as they have more built up nutrients left in the soil.


As for water only last 2 weeks somewhat reduced yield, less color, smell and ultimately flavor when cured. Does smoke smoothest right after drying. (Faded, deficient plant less chlorophyll) some plants stayed green to the end anyway)

i like to keep them as healthy as possible to harvest but some plants fade regardless. But the purposely starved and faded plants had the worst results except they were not that harsh after drying.

Fed steady to last week and then water only to harvest left some plants harsh even after curing and some had reduced potency and even frost. The non harsh flowers were fine but still not my best work.

Plants fed as needed and tapered down in strength as they ripen (chosen method) and fed to the end if needed but at a low strength or water if plenty green and healthy consistantly gave more yield, bud structure, flavor, and smell. And most important potency. However this can extend the flowering time as the flowers go into “overdrive” and have late growth spurts that result in more yield as well as more layers of trichomes obviously visible in the side by sides.

Sorry i dont have pics. Some of this is in the 315 lec thread on riu. We did cmh vs super hps vs hortilux blue too.

And we have chosen to use grow ratio complete nutes to the end but tapered off and have ditched bloom pl heavy formulas all together. In fact they shorten flowering and yellow plants prematurely in my experience.

We did have patients blind test flowers through the process. As well as mrs. Mmg and me.

:-)

 

[Dirtbag]

Recently had a discussion and I was corrected on a statement I made. It had to do with dark period before chop and the starches. I'm wondering if it has to do with starving the plant of nutrients results in extremely reduced production of starches etc. That are know to cause some harshness. This is where the claims of 24 he dark period comes into play.

I can't help but be curious if this is linked. And if you are starving them the last week there would be no need or little need for a longer dark period at chop and vice versa if you feed all the way a longer dark period would/could reduce that harshness you are referring to but also allow optimal growth of buds.

I dont know.. I usually do 36 hrs of dark before I chop and I did it on the last one too, and it still came out harsh. I was of the understanding that the dark period is because the plant shunts sugars and waste products out of the plant and into the media in the dark, and also THC and terpene production and content is at its peak at the end of the dark cycle, while some is volitalized with the lights on.

 

[MIMedGrower]

Recently had a discussion and I was corrected on a statement I made. It had to do with dark period before chop and the starches. I'm wondering if it has to do with starving the plant of nutrients results in extremely reduced production of starches etc. That are know to cause some harshness. This is where the claims of 24 he dark period comes into play.

I can't help but be curious if this is linked. And if you are starving them the last week there would be no need or little need for a longer dark period at chop and vice versa if you feed all the way a longer dark period would/could reduce that harshness you are referring to but also allow optimal growth of buds.

We have chosen to pull plants ready to harvest before the grow lights come on after noticing that plants harvested that were left a while under lights were harsher tasting longer. The starches do eventually cure out in the jars.

 

[Dirtbag]

Well a couple of years ago i ran 3 sets of known dialed in cuttings 3 times each test to compare all the forum stuff I read.

To note i grow in potting soil and err on the side of underfeeding so it is not usually necessary for me to leach pots to clear out salts often. I believe heavy feeders may benefit from water only last 2 weeks as they have more built up nutrients left in the soil.


As for water only last 2 weeks somewhat reduced yield, less color, smell and ultimately flavor when cured. Does smoke smoothest right after drying. (Faded, deficient plant less chlorophyll) some plants stayed green to the end anyway)

i like to keep them as healthy as possible to harvest but some plants fade regardless. But the purposely starved and faded plants had the worst results except they were not that harsh after drying.

Fed steady to last week and then water only to harvest left some plants harsh even after curing and some had reduced potency and even frost. The non harsh flowers were fine but still not my best work.

Plants fed as needed and tapered down in strength as they ripen (chosen method) and fed to the end if needed but at a low strength or water if plenty green and healthy consistantly gave more yield, bud structure, flavor, and smell. And most important potency. However this can extend the flowering time as the flowers go into “overdrive” and have late growth spurts that result in more yield as well as more layers of trichomes obviously visible in the side by sides.

Sorry i dont have pics. Some of this is in the 315 lec thread on riu. We did cmh vs super hps vs hortilux blue too.

And we have chosen to use grow ratio complete nutes to the end but tapered off and have ditched bloom pl heavy formulas all together. In fact they shorten flowering and yellow plants prematurely in my experience.

We did have patients blind test flowers through the process. As well as mrs. Mmg and me.

:-)

I'm curious if you were using pure blend pro for these experiments? I have a pet theory that pbp being organic has much less of a detrimental effect feeding up to the end compared to feeding a standard mineral based nutrient. In fact it might even require it.
I will say, feeding floranova right to the end was no bueno.

 

[Beachwalker]

Taper, not flush. In soil some plants receive some nutrients right up to harvest, most plants receive nothing but plain water for 3 - 10 days or more, depends on what they want & need ?

 

[Aqua Man]

I dont know.. I usually do 36 hrs of dark before I chop and I did it on the last one too, and it still came out harsh. I was of the understanding that the dark period is because the plant shunts sugars and waste products out of the plant and into the media in the dark, and also THC and terpene production and content is at its peak at the end of the dark cycle, while some is volitalized with the lights on.

Yeah you have to excuse me. I'm pretty dam high since I got home so in probably not making much sense. What I mean is by starving them that are not able to produce sugars and waste so less need for the dark period. I was kinda thinking aloud wondering if they are related. Basically wondering if you starve them they won't produce as much and if you fed longer and used a longer dark period would the result be the same.

Sorry baked af

 

[Aqua Man]

Taper, not flush. In soil some plants receive some nutrients right up to harvest, most plants receive nothing but plain water for 3 - 10 days or more, depends on what they want & need ?

I agree... Flush doesn't actually reduce the nutrients to nothing. It lowers the overall feed. This is why I feel flushing in hydro is not at all needed.

 

[Dirtbag]

I agree... Flush doesn't actually reduce the nutrients to nothing. It lowers the overall feed. This is why I feel flushing in hydro is not at all needed.

Again I'm not so sure.. My buddies that run drip hydro in a big LP kept getting customer complaints about their pot not burning properly and black ash etc, and that was with 3 days of straight water at the end.
They ended up having to go with 5 days of plain water at the end to get a product that didnt draw complaints.

And they cure their buds carefully in a climate controlled curing chamber. Buds still burned black.

This is one of those interesting subjects that has Avid proponents on both sides but little real science behind it. All I can do is grow based on personal experiences. And on that I feel i get the best product by feeding (not flushing) plain water for the last 2-3 waterings.

 

[Aqua Man]

Again I'm not so sure.. My buddies that run drip hydro in a big LP kept getting customer complaints about their pot not burning properly and black ash etc, and that was with 3 days of straight water at the end.
They ended up having to go with 5 days of plain water at the end to get a product that didnt draw complaints.

And they cure their buds carefully in a climate controlled curing chamber. Buds still burned black.

This is one of those interesting subjects that has Avid proponents on both sides but little real science behind it. All I can do is grow based on personal experiences. And on that I feel i get the best product by feeding (not flushing) plain water for the last 2-3 waterings.

Yeah if they had been overfed nothing will pull it out. I feel the key is feeding just enough. But there are so many variables it's not easy to pinpoint one because they all effect each other. Personally I don't mind seeing some very minor deficiencies mid to late flower. Although I try to keep the nutrients just enough so as not to see them I would rather feed a tad to little than to much. In a big facility with a variety of strains, sizes of individual plants etc. That's not so easily accomplished. So flushing might be beneficial? The way I see it is even if you flush in soil they are still getting some nutrients.

 

[Aqua Man]

There are so many variables that can affect the flavor this is a tough subject to tackle. I can say definitively that flushing does not pull excess nutrients out of the plants.

I can't explain why flushing would benefit other than to reduce the amount of feed available for uptake. Which leaves me stuck on the idea that limiting the food supply would limit the production of starches, sugars etc. that are transported to the roots during the dark period that can lead to a harsh taste. And the possibility of increasing the need to extend the dark period when not starving the plants.

I wish there was more scientific research on this.

 

[Dirtbag]

Yeah if they had been overfed nothing will pull it out. I feel the key is feeding just enough. But there are so many variables it's not easy to pinpoint one because they all effect each other. Personally I don't mind seeing some very minor deficiencies mid to late flower. Although I try to keep the nutrients just enough so as not to see them I would rather feed a tad to little than to much. In a big facility with a variety of strains, sizes of individual plants etc. That's not so easily accomplished. So flushing might be beneficial? The way I see it is even if you flush in soil they are still getting some nutrients.

For sure, my input 2 weeks out from harvest is 1.5ec, runoff will be 1.6-1.8 ec.

For my last 3 water only feedings the runoff will drop to like 1.2- 1.0 - 0.8.. So there is absolutely still nutrients in the soil. There has to be residual nutes in any media which has a CEC unless you use a flushing agent. I never actually flush all the nutrients out.

 

[MIMedGrower]

I'm curious if you were using pure blend pro for these experiments? I have a pet theory that pbp being organic has much less of a detrimental effect feeding up to the end compared to feeding a standard mineral based nutrient. In fact it might even require it.
I will say, feeding floranova right to the end was no bueno.

Thats another test. Lol. But for the above we used botanicare kind. I wanted more immediate control than the natural based stuff would have.

But for pk leaning nutes same results with kind and pure blend pro. Veg only kept plants healthier.