To flush or not to flush
- Thread starter Alkaprawn
- Start date
Alienwidow
Well-Known Member
Nah, just cut back on nitrogen and calmag at the end of flower.
sunny747
Well-Known Member
May depend on your nutes.. If u use Miracle grow or cheap nutes then probably... If you take the time to use organics then why bother? I say go ahead and flush the soil very well a few days before harvest and make sure you top off with a few gallons of RO water.. It just sort of makes sense to me. Is it necessary? No. It may also depend on when you harvest. I harvest late. It's not making a difference in the weight.
Let's say it depends and is a matter of preference.
Let's say it depends and is a matter of preference.
chuck estevez
Well-Known Member
only if yo use the right products
BDOGKush
Well-Known Member
Extremely informative post from 420mag, please read this if you're wondering if you should flush or not.
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 even suggest reduced yield and quality.
The theory of pre harvest flushing is to remove nutrients from the grow medium/root zone. A lack of nutrients creates a deficiency, forcing the plant to translocate and use up its internal nutrient compounds.
Nutrient fundamentals and uptake:
The nutrient uptake process is explained in this faq.
A good read about plant nutrition can be found here.
Until recently it was common thought that all nutrients are absorbed by plant roots as ions of mineral elements. However in newer studies more and more evidence emerged that additionally plant roots are capable of taking up complex organic molecules like amino acids directly thus bypassing the mineralization process.
The major nutrient uptake processes are:
1) Active transport mechanism into root hairs (the plant has to put energy in it, ATP driven) which is selective to some degree. This is one way the plant (being immobile) can adjust to the environment.
2) Passive transport (diffusion) through symplast to endodermis.
‘chemical’ ferted plants need to be flushed should be taken with a grain of salt. Organic and synthetic ferted plants take up mineral ions alike, probably to a different degree though. Many influences play key roles in the taste and flavor of the final bud, like the nutrition balance and strength throughout the entire life cycle of the plant, the drying and curing process and other environmental conditions.
3) Active transport mechanism of organic molecules into root hairs via endocytosis.
Here is a simplified overview of nutrient functions:
Nitrogen is needed to build chlorophyll, amino acids, and proteins. Phosphorus is necessary for photosynthesis and other growth processes. Potassium is utilized to form sugar and starch and to activate enzymes. Magnesium also plays a role in activating enzymes and is part of chlorophyll. Calcium is used during cell growth and division and is part of the cell wall. Sulfur is part of amino acids and proteins.
Plants also require trace elements, which include boron, chlorine, copper, iron, manganese, sodium, zinc, molybdenum, nickel, cobalt, and silicon.
Copper, iron, and manganese are used in photosynthesis. Molybdenum, nickel, and cobalt are necessary for the movement of nitrogen in the plant. Boron is important for reproduction, while chlorine stimulates root growth and development. Sodium benefits the movement of water within the plant and zinc is neeeded for enzymes and used in auxins (organic plant hormones). Finally, silicon helps to build tough cell walls for better heat and drought tolerance.
You can get an idea from this how closely all the essential elements are involved in the many metabolic processes within the plant, often relying on each other.
Nutrient movement and mobility inside the plant:
Besides endocytosis, there are two major pathways inside the plant, the xylem and the phloem. When water and minerals are absorbed by plant roots, these substances must be transported up to the plant's stems and leaves for photosynthesis and further metabolic processes. This upward transport happens in the xylem. While the xylem is able to transport organic compounds, the phloem is much more adapted to do so.
The organic compounds thus originating in the leaves have to be moved throughout the plant, upwards and downwards, to where they are needed. This transport happens in the phloem. Compounds that are moving through the phloem are mostly:
Sugars as sugary saps, organic nitrogen compounds (amino acids and amides, ureides and legumes), hormones and proteins.
Not all nutrient compounds are moveable within the plant.
1) N, P, K, Mg and S are considered mobile: they can move up and down the plant in both xylem and phloem.
Deficiency appears on old leaves first.
2) Ca, Fe, Zn, Mo, B, Cu, Mn are considered immobile: they only move up the plant in the xylem.
Deficiency appears on new leaves first.
Storage organelles:
Salts and organic metabolites can be stored in storage organelles. The most important storage organelle is the vacuole, which can contribute up to 90% of the cell volume. The majority of compounds found in the vacuole are sugars, polysaccharides, organic acids and proteins though.
Translocation:
Now that the basics are explained, we can take a look at the translocation process. It should be already clear that only mobile elements can be translocated through the phloem. Immobile elements cant be translocated and are not more available to the plant for further metabolic processes and new plant growth.
Since flushing (in theory) induces a nutrient deficiency in the rootzone, the translocation process aids in the plants survival. Translocation is transportation of assimilates through the phloem from source (a net exporter of assimilate) to sink (a net importer of assimilate). Sources are mostly mature fan leaves and sinks are mostly apical meristems, lateral meristem, fruit, seed and developing leaves etc.
You can see this by the yellowing and later dying of the mature fan leaves from the second day on after flushing started. Developing leaves, bud leaves and calyxes don’t serve as sources, they are sinks. Changes in those plant parts are due to the deficient immobile elements which start to indicate on new growth first.
Unfortunately, several metabolic processes are unable to take place anymore since other elements needed are no longer available (the immobile ones). This includes processes where nitrogen and phosphorus, which have likely the most impact on taste, are involved.
For example nitrogen: usually plants use nitrogen to form plant proteins. Enzyme systems rapidly reduce nitrate-N (NO3-) to compounds that are used to build amino-nitrogen which is the basis for amino acids. Amino acids are building blocks for proteins, most of them are plant enzymes responsible for all the chemical changes important for plant growth.
Sulfur and calcium among others have major roles in production and activating of proteins, thereby decreasing nitrate within the plant. Excess nitrate within the plant may result from unbalanced nutrition rather than an excess of nitrogen.
Summary:
Preharvest flushing puts the plant(s) under serious stress. The plant has to deal with nutrient deficiencies in a very important part of its cycle. Strong changes in the amount of dissolved substances in the root-zone stress the roots, possibly to the point of direct physical damage to them. Many immobile elements are no more available for further metabolic processes. We are loosing the fan leaves and damage will show likely on new growth as well.
The grower should react in an educated way to the plant needs. Excessive, deficient or unbalanced levels should be avoided regardless the nutrient source. Nutrient levels should be gradually adjusted to the lesser needs in later flowering. Stress factors should be limited as far as possible. If that is accomplished throughout the entire life cycle, there shouldn’t be any excessive nutrient compounds in the plants tissue. It doesn’t sound likely to the author that you can correct growing errors (significant lower mobile nutrient compound levels) with preharvest flushing.
Drying and curing (when done right) on the other hand have proved (In many studies) to have a major impact on taste and flavour, by breaking down chlorophylls and converting starches into sugars. Most attributes blamed on unflushed buds may be the result of unbalanced nutrition and/or overfert and unproper drying/curing.
http://www.420magazine.com/forums/how-grow-marijuana/71685-critical-look-preharvest-flushing.html
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 even suggest reduced yield and quality.
The theory of pre harvest flushing is to remove nutrients from the grow medium/root zone. A lack of nutrients creates a deficiency, forcing the plant to translocate and use up its internal nutrient compounds.
Nutrient fundamentals and uptake:
The nutrient uptake process is explained in this faq.
A good read about plant nutrition can be found here.
Until recently it was common thought that all nutrients are absorbed by plant roots as ions of mineral elements. However in newer studies more and more evidence emerged that additionally plant roots are capable of taking up complex organic molecules like amino acids directly thus bypassing the mineralization process.
The major nutrient uptake processes are:
1) Active transport mechanism into root hairs (the plant has to put energy in it, ATP driven) which is selective to some degree. This is one way the plant (being immobile) can adjust to the environment.
2) Passive transport (diffusion) through symplast to endodermis.
‘chemical’ ferted plants need to be flushed should be taken with a grain of salt. Organic and synthetic ferted plants take up mineral ions alike, probably to a different degree though. Many influences play key roles in the taste and flavor of the final bud, like the nutrition balance and strength throughout the entire life cycle of the plant, the drying and curing process and other environmental conditions.
3) Active transport mechanism of organic molecules into root hairs via endocytosis.
Here is a simplified overview of nutrient functions:
Nitrogen is needed to build chlorophyll, amino acids, and proteins. Phosphorus is necessary for photosynthesis and other growth processes. Potassium is utilized to form sugar and starch and to activate enzymes. Magnesium also plays a role in activating enzymes and is part of chlorophyll. Calcium is used during cell growth and division and is part of the cell wall. Sulfur is part of amino acids and proteins.
Plants also require trace elements, which include boron, chlorine, copper, iron, manganese, sodium, zinc, molybdenum, nickel, cobalt, and silicon.
Copper, iron, and manganese are used in photosynthesis. Molybdenum, nickel, and cobalt are necessary for the movement of nitrogen in the plant. Boron is important for reproduction, while chlorine stimulates root growth and development. Sodium benefits the movement of water within the plant and zinc is neeeded for enzymes and used in auxins (organic plant hormones). Finally, silicon helps to build tough cell walls for better heat and drought tolerance.
You can get an idea from this how closely all the essential elements are involved in the many metabolic processes within the plant, often relying on each other.
Nutrient movement and mobility inside the plant:
Besides endocytosis, there are two major pathways inside the plant, the xylem and the phloem. When water and minerals are absorbed by plant roots, these substances must be transported up to the plant's stems and leaves for photosynthesis and further metabolic processes. This upward transport happens in the xylem. While the xylem is able to transport organic compounds, the phloem is much more adapted to do so.
The organic compounds thus originating in the leaves have to be moved throughout the plant, upwards and downwards, to where they are needed. This transport happens in the phloem. Compounds that are moving through the phloem are mostly:
Sugars as sugary saps, organic nitrogen compounds (amino acids and amides, ureides and legumes), hormones and proteins.
Not all nutrient compounds are moveable within the plant.
1) N, P, K, Mg and S are considered mobile: they can move up and down the plant in both xylem and phloem.
Deficiency appears on old leaves first.
2) Ca, Fe, Zn, Mo, B, Cu, Mn are considered immobile: they only move up the plant in the xylem.
Deficiency appears on new leaves first.
Storage organelles:
Salts and organic metabolites can be stored in storage organelles. The most important storage organelle is the vacuole, which can contribute up to 90% of the cell volume. The majority of compounds found in the vacuole are sugars, polysaccharides, organic acids and proteins though.
Translocation:
Now that the basics are explained, we can take a look at the translocation process. It should be already clear that only mobile elements can be translocated through the phloem. Immobile elements cant be translocated and are not more available to the plant for further metabolic processes and new plant growth.
Since flushing (in theory) induces a nutrient deficiency in the rootzone, the translocation process aids in the plants survival. Translocation is transportation of assimilates through the phloem from source (a net exporter of assimilate) to sink (a net importer of assimilate). Sources are mostly mature fan leaves and sinks are mostly apical meristems, lateral meristem, fruit, seed and developing leaves etc.
You can see this by the yellowing and later dying of the mature fan leaves from the second day on after flushing started. Developing leaves, bud leaves and calyxes don’t serve as sources, they are sinks. Changes in those plant parts are due to the deficient immobile elements which start to indicate on new growth first.
Unfortunately, several metabolic processes are unable to take place anymore since other elements needed are no longer available (the immobile ones). This includes processes where nitrogen and phosphorus, which have likely the most impact on taste, are involved.
For example nitrogen: usually plants use nitrogen to form plant proteins. Enzyme systems rapidly reduce nitrate-N (NO3-) to compounds that are used to build amino-nitrogen which is the basis for amino acids. Amino acids are building blocks for proteins, most of them are plant enzymes responsible for all the chemical changes important for plant growth.
Sulfur and calcium among others have major roles in production and activating of proteins, thereby decreasing nitrate within the plant. Excess nitrate within the plant may result from unbalanced nutrition rather than an excess of nitrogen.
Summary:
Preharvest flushing puts the plant(s) under serious stress. The plant has to deal with nutrient deficiencies in a very important part of its cycle. Strong changes in the amount of dissolved substances in the root-zone stress the roots, possibly to the point of direct physical damage to them. Many immobile elements are no more available for further metabolic processes. We are loosing the fan leaves and damage will show likely on new growth as well.
The grower should react in an educated way to the plant needs. Excessive, deficient or unbalanced levels should be avoided regardless the nutrient source. Nutrient levels should be gradually adjusted to the lesser needs in later flowering. Stress factors should be limited as far as possible. If that is accomplished throughout the entire life cycle, there shouldn’t be any excessive nutrient compounds in the plants tissue. It doesn’t sound likely to the author that you can correct growing errors (significant lower mobile nutrient compound levels) with preharvest flushing.
Drying and curing (when done right) on the other hand have proved (In many studies) to have a major impact on taste and flavour, by breaking down chlorophylls and converting starches into sugars. Most attributes blamed on unflushed buds may be the result of unbalanced nutrition and/or overfert and unproper drying/curing.
http://www.420magazine.com/forums/how-grow-marijuana/71685-critical-look-preharvest-flushing.html
Gary Goodson
Well-Known Member
@chuck estevez I've been using the flushy flush for years bruh bruh and my shitz is some FIRE niggs!
Peep it
Nigga whaaaaaaaaaaaaaa
Peep it
Nigga whaaaaaaaaaaaaaa
vitamin_green_inc
Well-Known Member
Good info, but it seems like the shock is there, which means the plant realizes it's life span is over correct?
So a pre harvest flush of say, less than a week before chopping, would be a signal to the plant to attempt to carry on its genetics by putting its all into the flowers for one last gasp?
Much the same as fall coming and rain/cold setting in thereby inhibiting nutrient uptake in a normal fashion? School me with more good info @BDOGKush lol
So a pre harvest flush of say, less than a week before chopping, would be a signal to the plant to attempt to carry on its genetics by putting its all into the flowers for one last gasp?
Much the same as fall coming and rain/cold setting in thereby inhibiting nutrient uptake in a normal fashion? School me with more good info @BDOGKush lol
But, are those beneficial experiences to the plant? Or, are we improving upon nature by maintaining stable temps, constant humidity, just enough darkness to maintain flowering (not going into winter and shorter "days")?
Feeding to the end would just be another improvement on nature?
I think the only deciding factors about whether to flush are 1) if someone is a typical overfeeder, and 2) whether they are in soil and whether they use a fair amount of organic nutes.
For example, if someone overfeeds, if they struggle with salt buildup (glossy, brittle leaves) and they flush between veg and flower as a matter of routine (i.e., many cannabis growers who use boutique "lineups"), they should probably flush at the end, or feed weaker nutrients the last 2-3 feedings. We can rationalize it as "the plant suffers in nature too." But, it's really about how it suffered the whole time with too much nutes.
Or, if someone uses synthetic nutes in soil (like, GH Flora 3-part), I'd flush that (or feed less).
I urge everyone to try it with and without flush, mild end feeding and no change. You never know until you try it yourself. I think that's important because there are so many factors that might make it useful for one person and not another.
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panhead
Well-Known Member
Ive been growing dope since the 70's , the whole concept of flushing was unheard of until nute manufacturers strated making products to help us flush , pfffft .
The only thing you need to flush is your toilet , start cutting back the N after week 4 & your good to go , feed them bitches till the day you chop .
The more you " READ " about growing the more shit people think they need to do .
The only thing you need to flush is your toilet , start cutting back the N after week 4 & your good to go , feed them bitches till the day you chop .
The more you " READ " about growing the more shit people think they need to do .
vitamin_green_inc
Well-Known Member
Exactly, there are many factors and so each grower will have what is optimal for them. Especially true about the 1.amount of Nutes over the lifespan of the plant and 2. Whether they are chemical, direct feed to the root system or organic and feeding the soil.
BDOGKush
Well-Known Member
I agree that feeding to the end is the way to go. The color change we see in nature during Autumn is caused by there not being enough light and water for the plant to photosynthesis, so the plant stops producing chlorophyll. Its not that the earth ran out of enough nutrients to support plant life.
A question I'd pose is that plants do not store nutrients in their flowers, so what are you really flushing at preharvest? I'd say just your soil and not the plant itself.
I'm a soil grower using GH Floranova and used to flush. I tried not flushing and came to my own conclusion that flushing to avoid a "chemical" taste to your flowers was a false teaching. I still get compliments about how well my flowers were flushed, I just smile and nod.