To flush, or not to flush.. That is the question.

[GrumpAzz]

I asked this in my thread sometime back but I thought I would post it up for all to chime in.

Do you flush your hydroponic grow before harvest? Why or why not?

Nearly everything on the great Google says to flush but I know several of you do not. Explain to me your reasoning so I can at least debate the subject with a friend of mine who used to grow in soil. I know @smoke does not but I've never smoked smoke's smoke. I believe @Rootsruler also said he doesn't flush. Someone else mentioned something along the lines of no other plants of importance are starved of nutrients in their final stages of life. Was that @Stoneyluv? Or maybe it was @GoodShit97..

Either way.. I'm open to opinions and would love to see what everyone else has to say.

 

[GoodShit97]

I asked this in my thread sometime back but I thought I would post it up for all to chime in.

Do you flush your hydroponic grow before harvest? Why or why not?

Nearly everything on the great Google says to flush but I know several of you do not. Explain to me your reasoning so I can at least drbate the subject with a friend of mine who used to grow in soil. I know @smoke does not but I've never smoked smoke's smoke. I believe @Rootsruler also said he doesn't smoke. Someone else mentioned something along the lines of no other plants of importance are starved of nutrients in their final stages of life. Was that @Stoneyluv? Or maybe it was @GoodShit97..

Either way.. I'm open to opinions and would love to see what everyone else has to say.

I dont flush because ive never heard of any crop getting flushed before harvest. Plus it just doesnt sound right.
In hydro id imagine you would just lower ppms to like 250-300 and run it to the end? Idk tho ive never done hydro.

Ive flushed and not flushed, and i actually prefer the unflushed product as it seemed to be extra flavorful and more potent.

 

[Moshmen]

No flush here either minor cut backs in weeks prior to harvest but button to serious

 

[Rootsruler]

I think it's more semantics than anything else. I don't "flush" so much as I taper down the inputs so that the plant can use up whatever food remains in its leaves and in the soil. Instead of flushing I would call it starving.

 

[GrumpAzz]

I think it's more semantics than anything else. I don't "flush" so much as I taper down the inputs so that the plant can use up whatever food remains in its leaves and in the soil. Instead of flushing I would call it starving.

So I've tapered this round of nutes down to 400ppms from 650 a couple weeks ago. Would you consider this a sufficient "flush"?

 

[GrumpAzz]

Hey @Pipecarver, I think you replied to the wrong thread

We've seen people add ice to cool the roots prior to harvest. Bro Science? I was wondering about using my chiller as a way to do the same thing. I'm not sure how low I can set it but would there be any benefit or cause more harm by not letting the roots uptake anything?

 

[Pipecarver]

Hey @Pipecarver, I think you replied to the wrong thread

To many tabs open to keep track I guess......2 is more than I can handle at once or faux pas happen

 

[Max]

So I've tapered this round of nutes down to 400ppms from 650 a couple weeks ago. Would you consider this a sufficient "flush"?

Abit more.go to 300. in all honesty,you can’t flush out what a plants taken up..there’s been tests on plants flushed and not and there wasn’t any difference.you only really have to flush if you was feeding with a high ppm.

 

[Max]

I’ve pulled at 4-500 and my mate couldn’t tell the difference..I use him as a Guinea pig …what you don’t know dont hurt you haha..

 

[smoke]

I don't flush, i only feed them what they eat daily , nothing much to flush

@Pipecarver ive never tried lowering the water temperature, i have lowered the air temperature to bring out some color.

Did a bro trial on my 4 plants, for the last 3 weeks using the fan from the split ac unit, i directed the fan from ac at plant #4 and it did appear to have more color than the other 3 plants

 

[Pipecarver]

I’ve pulled at 4-500 and my mate couldn’t tell the difference..I use him as a Guinea pig …what you don’t know dont hurt you haha..

DR. Bruce Bugby did a piece on that and he said there was little if any evidence that flushing did anything and quoted blind tests done that showed the opposite and unflushed was given a higher rating than flushed for flavor, burn ability and a few other categories I can't remember. I've ( in soil ) water/ feed/ water / feed and try to finish after a water cycle but that doesn't always work out. Now in my Auto pots I'm just reducing nutes as they flower past week 9. Last night I fed 5/5/10ml into 3 gallons. my ppm is just over 400 10 weeks into flower.

 

[Max]

yeah that’s all I do too.sometimes I check the tricks a day later and I’m like ..it’s gotta go and don’t get to reduce the feed a little lower.but I’m always at low ppms around 400 odd when they are just about done..

 

[GrumpAzz]

DR. Bruce Bugby did a piece on that and he said there was little if any evidence that flushing did anything and quoted blind tests done that showed the opposite and unflushed was given a higher rating than flushed for flavor, burn ability and a few other categories I can't remember. I've ( in soil ) water/ feed/ water / feed and try to finish after a water cycle but that doesn't always work out. Now in my Auto pots I'm just reducing nutes as they flower past week 9. Last night I fed 5/5/10ml into 3 gallons. my ppm is just over 400 10 weeks into flower.

I'll have to check into that video. It'd be easier to just send him a link than try to argue something I'm clueless about. He just says he could definitely tell a difference when he didn't flush in soil. Maybe he never did a side-by-side and was judging one run against another which could obviously yield different results.

 

[GrumpAzz]

I'll have to check into that video. It'd be easier to just send him a link than try to argue something I'm clueless about. He just says he could definitely tell a difference when he didn't flush in soil. Maybe he never did a side-by-side and was judging one run against another which could obviously yield different results.

Right around 41 minutes he talks about flushing. Is this in your Bugby thread @Observer?

 

[Pipecarver]

Right around 41 minutes he talks about flushing. Is this in your Bugby thread @Observer?

That's not the video I saw him talk about it similar info but he quoted a study a university did and in blind tastes tests the un flushed was preferred to the flushed....I wasn't there so I have to take his word for it.

 

[Pipecarver]

I don't flush, i only feed them what they eat daily , nothing much to flush

@Pipecarver ive never tried lowering the water temperature, i have lowered the air temperature to bring out some color.

Did a bro trial on my 4 plants, for the last 3 weeks using the fan from the split ac unit, i directed the fan from ac at plant #4 and it did appear to have more color than the other 3 plants

Oh I'm 100% sure cool nights bring out the color. My winter grows with a 64f basement and cooler in the corner always gives me color I've a purple Gorilla somewhere in my pics and this jam/gsc

 

[TomH]

I think I need to study in his ag courses! Great information.

 

[Bandit420]

I believe flushing was only required when growing in rockwool slabs with recirculating irrigation to prevent salt build up causing lockout or toxicity issues. This is also where leaching trays come into play and help with that. Now there's salt thinners people can use so they don't have to run so many gallons of water flushing the medium out.

I don't consider just water at the end a flush because it's just watering and flushing takes a lot of water to get a medium back down to 0ppm.
I have seen DWC raise ppm with a zero ppm flush though. Some believe roots can kick nutes back out but I'm not sure if it's really that or just salt build up on the roots & plastics that takes a zero ppm up several hundred points

 

[Observer]

Right around 41 minutes he talks about flushing. Is this in your Bugby thread @Observer?

I think I got that one in there I'll check

 

[Observer]

Oh I'm 100% sure cool nights bring out the color. My winter grows with a 64f basement and cooler in the corner always gives me color I've a purple Gorilla somewhere in my pics and this jam/gscView attachment 21087View attachment 21088

Colder weather/lower temperature plays a role in anthocyanins, so yes colder temps can affect color changing.

Ever stick a male outside during winter season?
I've seen the seed or pollen sacs change darker purple.

 

[Observer]

Gonna post this here too


There's

Flushing - flushing excess salts out of the media, wether trying to flush out organics that's too hot,
Or flushing out synthetic salts.

Flushing - "in an attempt to "flush" out the plant and any excess salts/nutrients in the plant to make for a smoother smoke ------ this is not going to happen, whatever the plant as uptaken or already absorbed isnt coming out.

Flushing - reset the media, similar to first point.

All different context.

 

[Dirtbag]

I use plain water with a clearing agent containing magnesium sulphate for a few days at the end. Having tried all the different ways to finish the crop, it gives me the cleanest, best burning product.

 

[SweetLeafGrow]

In hydro, I've learned to let my plants and the water itself tell me what they want at the end of their cycle (and the beginning for that matter, in reverse). Going my first run using this new way of doing things right now with the Apples and Bananas in the 5x5. In hydro, PPMs staying the same and ph dropping signifies the plant wants less nutrients, the res is too hot nutrient wise. I had this scenario coming through week 6 flower and the ph started to dive while ppms remained static, this after being super stable since flip. Instead of just fixing that with pH adjusters like I had done in the past, I lowered the ppms gradually by topping off with plain RO water over the course of a few days and brought it from around 530 to where it is now to 290 with about a week left til chop. My RO water is 7.0-7.1 so I hardly had to use any pH adjusters at all during this process. I topped off today at that 290 ppm with late flower ratios as she finally stabilized a couple of days ago and she's still stable at that 290 number for now.

I would not call this a flush at all. It's just giving the plants what they want. I did notice I am not getting much of a colorful fade doing it this way. I'm guessing they don't need to pull that nutirent supply from the fans when they have everything they need in the water? The flowers themselves are very colorful and starting to really look beautiful.

 

[GrumpAzz]

In hydro, I've learned to let my plants and the water itself tell me what they want at the end of their cycle (and the beginning for that matter, in reverse). Going my first run using this new way of doing things right now with the Apples and Bananas in the 5x5. In hydro, PPMs staying the same and ph dropping signifies the plant wants less nutrients, the res is too hot nutrient wise. I had this scenario coming through week 6 flower and the ph started to dive while ppms remained static, this after being super stable since flip. Instead of just fixing that with pH adjusters like I had done in the past, I lowered the ppms gradually by topping off with plain RO water over the course of a few days and brought it from around 530 to where it is now to 290 with about a week left til chop. My RO water is 7.0-7.1 so I hardly had to use any pH adjusters at all during this process. I topped off today at that 290 ppm with late flower ratios as she finally stabilized a couple of days ago and she's still stable at that 290 number for now.

I would not call this a flush at all. It's just giving the plants what they want. I did notice I am not getting much of a colorful fade doing it this way. I'm guessing they don't need to pull that nutirent supply from the fans when they have everything they need in the water? The flowers themselves are very colorful and starting to really look beautiful.

Perfect. Thats exactly what I'd been seeing these last couple days and was wanting tonassume the same thing. My pH had been pretty stable for the last week and, although we top-off a bit differently, my ppms kind of stalled out around 400 while the pH started to take a dive. She's still drinking 5+ quarts a day so that led me to assume she was done eating. Thanks for the example, bro. I think it was 2 days ago when I adjusted the pH for the first time in a week or more. I'll quit that and just pull out a gallon or so and refill with RO. Mine comes out around 5.8-6.

This place is a wealth of knowledge. Thanks to all for commenting and sharing your experiences.

 

[MysticEpipedon]

You can flush media. Flushing plants doesn't work, as many growers who live in illegal states have found out. Plumbing just doesn't carry those stalks too well, especially when LEO is at the door.

For flushing to work, the membranes in root cells and tissues would have to break down and stop working, which doesn't happen in living plants. Water and nutrients enter the roots, the water ends up released as vapor by the leaves. There is no way for the substances carried by that water to escape the plant.

If plants do taste better when starved at the end, it's not from washing out substances.

 

[ZombieRider]

You can flush media. Flushing plants doesn't work, as many growers who live in illegal states have found out. Plumbing just doesn't carry those stalks too well, especially when LEO is at the door.

For flushing to work, the membranes in root cells and tissues would have to break down and stop working, which doesn't happen in living plants. Water and nutrients enter the roots, the water ends up released as vapor by the leaves. There is no way for the substances carried by that water to escape the plant.

If plants do taste better when starved at the end, it's not from washing out substances.

I've flushed and not flushed throughout my runs last couple years. Honestly...I feel like flushing at least a day or two before harvest makes my ash whiter vs not flushed? Maybe it's been a coincidence, but wouldn't the plant be up taking nutrients actively b4 harvest and so adding to the amount of nutrients in the plant before harvesting? If its just drinking RO in its final days, it's at least not adding to the total amount of nutes in the buds. To truly test this I guess I'd just need 2 clones and flush one and not the other...smoke em and see.

 

[LJFarming]

As always I will never think one way is better than another! Do what works for you!

That said in Coco DTW and possibly any hydro grow technique this is how it was explained to me many moons ago:

Does an athlete only drink water for X# of days before the competition? As well as The lady’s are potentially like a woman ready to give birth? In hydro the grower is playing god in a sense. Definitely do not take all their tacos away and expect them to be their best for the last X# of days! Perhaps they only want 2/3 tacos at the end instead of being force fed 10-20 tacos per day? But IMO guaranteed the athlete or woman still needs to eat???? Long story short feed them until the end in hydro the amount/PPM needs to be determined by the grower and grow.

I was taught by an ole head a long time ago to dwindle over the last week from 1.5 EC to somewhere around .5 EC. But definitely do not starve the trophy you have spent the last 12+ weeks creating.

That’s how I roll! Right, Wrong, or Indifferent it works for me!

Peace

 

[MysticEpipedon]

I've flushed and not flushed throughout my runs last couple years. Honestly...I feel like flushing at least a day or two before harvest makes my ash whiter vs not flushed? Maybe it's been a coincidence, but wouldn't the plant be up taking nutrients actively b4 harvest and so adding to the amount of nutrients in the plant before harvesting? If its just drinking RO in its final days, it's at least not adding to the total amount of nutes in the buds. To truly test this I guess I'd just need 2 clones and flush one and not the other...smoke em and see.

If you've got two identical plants, it's worth experimenting.

I cut back on nutrients toward the end, because I don't think the plants need them. But since I grow in organic soil, there are always nutrients available to them, just not much in the way of N.

 

[Pipecarver]

As always I will never think one way is better than another! Do what works for you!

That said in Coco DTW and possibly any hydro grow technique this is how it was explained to me many moons ago:

Does an athlete only drink water for X# of days before the competition? As well as The lady’s are potentially like a woman ready to give birth? In hydro the grower is playing god in a sense. Definitely do not take all their tacos away and expect them to be their best for the last X# of days! Perhaps they only want 2/3 tacos at the end instead of being force fed 10-20 tacos per day? But IMO guaranteed the athlete or woman still needs to eat???? Long story short feed them until the end in hydro the amount/PPM needs to be determined by the grower and grow.

I was taught by an ole head a long time ago to dwindle over the last week from 1.5 EC to somewhere around .5 EC. But definitely do not starve the trophy you have spent the last 12+ weeks creating.

That’s how I roll! Right, Wrong, or Indifferent it works for me!

Peace

I use the words, taper off. not cut off to describe my feeding at the end of their cycle. In soil with only weekly feeds that's more difficult but in my auto pot reservoir I can make daily adjustment down to 1/1/1 if need be

 

[ninjadip]

Either way it's damn near the same. I believe tapering off is the best practice.

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