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Dispelling The Myths: The Importance Of Flushing Your Plants Before Harvest

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Dispelling The Myths: The Importance Of Flushing Your Plants Before Harvest

plant flushing

The following blog on plant flushing is a guest post from Advanced Nutrients. The views, thoughts, and opinions expressed in the text belong solely to the author, and not necessarily to the CannaCon organization, employees or other related individuals.

Within the world of cultivation, there seems to be debate over the topic of plant flushing. Opponents of the technique believe that flushing plants prior to harvest will rob them of vital nutrients — an obviously bad idea. On the other side of the divide, advocates proclaim that flushing frees the plants of excess nutrients and contaminants and leads to an overall higher-quality product.

In this article, we’ll explore the truth about flushing: Precisely what it is, why it’s so important for growers to flush their plants, and the best way to go about flushing for maximum benefit.


What Is Flushing And Who Should Do It?

Before we get into the reasons why flushing your plants is so important, we need to understand exactly what it is. Flushing involves watering your plants without any added nutrients for a period of time — anywhere from a day or two to a week or more, depending on your growing medium — prior to harvesting. The purpose of this is to allow the plants time to use up the nutrients that have already built up within them, thereby lessening the overall nutrient and contaminant load of the final product.

We recommend flushing for growers of all types, whether hydro, coco coir or soil — though the time period for flushing will vary, depending on the medium.


The Importance Of Flushing

Though some in the industry have argued otherwise, the importance of flushing your plants has been affirmed by the vast majority of serious growers. Most experienced cultivators have tried not flushing before harvest, which has caused them to experience first-hand the glaring difference in quality of the yield.You see, during the growing cycle, your plants store excess amounts of nutrients, salts and other compounds. If you don’t allow the plants a chance to dispose of these surplus compounds by flushing them before harvest, your final product will be much harsher and more bitter tasting. Failing to flush can also cause your product to suffer from other negative side effects, such as black ash and an unpleasant chemical taste and smell.

The truth is, not flushing nutrients before harvest can seriously compromise the quality of your high-value crops.


To Flush Or Not To Flush: Examining The Arguments For And Against

Despite the overwhelming majority of growers who understand the importance of flushing and have verified its benefits through their own practice, there are some who argue against it.

The anti-flushers make a few bold claims, including:

  1. Robbing plants of nutrients at any stage of the grow cycle is counterproductive and does not benefit growth in any way.
  2. Once nutrients are absorbed into the plant tissues, they are there permanently. The plant cannot expel them or use them up simply by denying it more nutrients.
  3. If flushing was in fact a beneficial practice, then plants grown in hydro would always taste better than plants grown in soil because soil cannot be effectively flushed.
  4. Withholding nutrients causes stress to the plants, which impedes growth rather than encouraging it.
  5. Flushing plants is “pseudoscience” that has not been supported or backed by any legitimate scientific studies.

Let’s address these anti-flushing arguments one by one.

  1. Flushing your plants does not involve robbing them off nutrients. On the contrary, it allows your plants the chance to use the excess nutrients they have accumulated throughout the grow cycle. When you feed your crops full nutrient loads right up until the time of harvest, they retain an overabundance of compounds that affect the quality of the final product — including its taste, smell and overall smoothness.It’s also important to note that the main purpose behind flushing is not to encourage substantial new growth — although, flushing can cause your crop’s floral blooms to swell, since plants are not expelling all their energy on nutrient uptake.
  2. Any grower who has experienced nutrient burn knows the argument that plants cannot expel excess nutrients holds no weight. Ask any seasoned cultivator how to fix nutrient burn and they will tell you: You need to flush your plants and allow them time to use up the excess nutrients.The same logic applies to pre-harvest flushing. You’re giving your plants just enough time to use up surplus nutrients, salts and other compounds.
  3. The argument that soil can’t be effectively flushed is simply illogical and just plain wrong. Plants grown in soil can be flushed — it just takes a longer period of time than flushing plants grown in hydro or coco.
  4. It’s true that withholding nutrients places stress on plants and causes them to increase defense compounds. However, in certain plants, the primary defense compounds are actually the most desirable constituents, so flushing before harvest can significantly increase the value of the final product.
  5. At Advanced Nutrients, we employ the largest team of Ph.D. botanists, microbiologists, entomologists, hormone specialists and organic chemists in the industry. These scientists are dedicated solely to studying cultivation best practices and are constantly conducting laboratory research. The notion that plant flushing is “pseudoscience” is simply absurd.


The Truth About Flushing

Flushing plants before harvest is indeed a beneficial practice. However, there is a right way and a wrong way to go about it. In truth, the anti-flushers make a valid point when they say that it can rob your plants of nutrients — IF you are flushing with just plain water.The fact is, flushing with plain water can cause your plants to lose some floral growth and resin percentages. This is why it’s critical that you use a quality flushing agent that is designed specifically for the type of plants you grow.

When it comes to a flushing agent, you want to be sure to use one that contains a range of chelates. Chelates are organic compounds that can bind with other chemicals and substances. During the flushing process, these chelates will attach themselves to the excess nutrients, salts and other compounds in your plants and force them out.

At the same time, your plants utilize the stored nutrients they need during these last few days and hours prior to harvest. A high-quality flushing agent will provide your plants the support they need through this process, along with assisting them in purging the excess compounds that you don’t want in your final product.


Timing Is Key: When To Flush Your Plants

Along with using the right flushing agent, you need to ensure you’re flushing at the right time in order to reap the maximum benefits of flushing. Use the following as guidelines for flushing prior to harvest:

  • If you’re growing in soil, begin flushing between one and two weeks before harvest.
  • If you’re growing in coco, flush your plants for up to one week prior to harvest.
  • If you’re growing in hydro, your plants only need to be flushed for one to two days.

Of course, you’ll need to monitor your crops closely during the flushing process to ensure they don’t turn too yellow. Adjust your flushing times as necessary to find the ideal time for your plants.

To learn more about cultivation and nutrients visits


  1. Anthony on December 7, 2018 at 8:32 am

    my northernlights x big bud is going on 11 weeks cloudy trycomes with some clear trycomes new bud tip growth all over bud sites do i need to chop or wait 1 more week this train is 60 day to harvest not sure what to do

    • CB on April 14, 2019 at 8:48 pm

      Ia m having the same deal going on with mine. 11 weeks and still cloudy and clear. So I started taking the top ones in stages and I will choo the lower ones later to see what they do.. I will say the buds are sticky as he’ll that I already chop. They are curing now. If you figure yours out let us all know. I am growing under a 600w hps in ff soil. And ff nutes. With mammoth p.

    • Stewster on April 16, 2019 at 12:37 pm

      If you’re in soil, start your flush. Flushing your plants (Soil) for a week or so will still allow your trichomes to mature.

      • Bee deezle on January 24, 2020 at 9:47 pm

        Flushing is BULLSCHIFF and so is the darkness before harvest nonsense…..I’ve tried experiments with and with pout and my friends actually preferred 5(3 non flushed buds and the darkness before harvest is a load of bologna too

        • Trev on February 11, 2020 at 10:19 am

          Flushing is not bull. If you don’t see better results with flushed plants vs unflushed u ain’t flushing right. I took unflushed buds from a plant, dried and cured then flushed the rest (to under 50ppm run off day 1 of flush) then feed 0ppm water for 1 week(in coco) the flushed buds make a white ash and u can barely feel the smoke on your throat, top shelf. The unflushed burns dark almost black, is rough on the throat and has undesirable taste. If you don’t flush proper your comparison is void. It’s 100% neacessary for quality product

        • Mack on February 14, 2020 at 11:24 pm

          Zero science behind your claim. Zero proof. Just he said she said bro science. It’s people like you that create stupid growers.

          -I flush for 1.5 weeks. I give my plants 48 hours of darkness before chopping.
          -Then I hang my buds for 7 days.
          -Then I cure my buds in Mason jars with a 62% humidty boveda humidity pack and let them sit and cure for 2 months.

          The end result is the smoothest, cleanest high.
          The smoothest smoke with ZERO harshness on your lungs
          And nothing but pure white ash when it burns.

          I’ve had triple A that’s not flushed or cured properly and it tastes like mexican brick weed.

          People smoke my bud and say it’s the cleanest smoke they’ve ever had.

          So your friends are idiots and you just dont know good weed.
          Half fun smoking your fertilizer stud

          • Rob Gee on March 21, 2020 at 9:17 pm

            Sorry, Mack, Flushing doesn’t do anything but let plants finish up most growers truly never complete the entire stage of a plants life. I owned a Hydroponic store and trust me I know I heard every horror how a so-called experienced salt farmer messed up their girls but to tell you the truth most people think growing MJ is easy I sold so ballast, hoods every single nutrient, additives I could 3 months later they would walk back in to sell their equipment back, some just gave them back too. And I could tell a Candy farmer they never asked about anything just walked in grabbed nutrients by the gallon paid and were on their way ( I’m a Candy grower) have grown for 36+ years and hell yeah I would sell the **it out of flushing agents and make every grower believe they had to flush and growing in water culture of any kind I would 100% flush because the use of chemicals nutrients like Advanced Nutrients, the worst of them all, just like G.H I loved G.H until they sold out. Listen NPK you don’t need all those additives, you only need a 2 part or 3 because of your Base, your Grow, and Bloom I do use Blackstrap throughout the grow and 1 tablespoon all the way to my last week, I only water one more time without anything else and always keep a little Epsom salt on hand use it every other week if needed. That’s it. Stop wasting time and money look at the trichomes they will tell you I’m done.

      • Vwolff on April 15, 2020 at 7:14 pm

        So how many days in that week do you flush your plant?

        • Ifono on May 23, 2020 at 10:07 pm

          Love it

    • Linda Truax on July 13, 2019 at 6:41 am

      I found this information very helpful but could use an update from an experienced grower.

      • Don on June 20, 2020 at 3:42 am

        simple question how do you flush planet earth? my plants are outside in the ground how should i flush them? ding ding ding hope the light goes on. such BS in the name of ripping people off for profit. flushing is a joke.

    • John O on October 23, 2019 at 4:47 pm

      Wait til 20 percent of tricomes are amber and then turn all lights off for 3 days and then chop her down and hang.

  2. Don on December 23, 2018 at 5:52 am

    Please do tell of any other industries that practice this stoner “Art” of “Flushing”? Don’t get me wrong i am a firm believer in nutrient reduction at the end of the plants life cycle.

    • Mark on January 22, 2020 at 5:42 pm

      Exactly Don. Do you see greenhouses doing this? Nope. Do you see tobacco farmers doing this? Nope. This is purely stoner science.

      • TeK-NiKaL on February 7, 2020 at 5:26 am

        I’m an experienced grower. It’s simple… use the Advanced Nutrients flushing agent as directed and enjoy the white ash and smoothest smoke ever. Im not a schill… just a lover of quality buds. I’m very sensitive to harsh smoke. It’s simple for me. I flush with the AN agent, I don’t get a sore throat. I smoke something that hasn’t been flushed with an agent I get a sore throat every time. I’m sorry folks but that black ash is from nutrients left locked up in the plant. A plain water flush will help, but it doesn’t do the complete job. AN is correct… the nutes chemically bind to the plant at a molecular level. Plain water won’t break those bonds. And the reason you don’t see tobacco farmers doing it is because the cig companies add all sorts of other chemicals to the final product anyway. Why worry about nutes when they’re adding arsenic to the tobacco. Please be smart and don’t be lazy. If you want quality product that stands above the rest… you must use a flushing agent. I don’t flush for weeks. I think that will affect your plant growth. I flush my medium with approx 1 gal. Of water each… then use the flushing agent. I let it sit for no longer than 24 hours… then flush my medium again with another gal. I let them sit for a day or two… until my medium is beginning to get dry… then harvest. Easy… and then you must have a proper dry. Don’t rush it! Keep your temp and humidity constant with a gentle suction of air in your drying area. Your dry should take at least 5 days…7 days is optimal. You must allow time for the proper conversion of thc-a to thc. I know it sucks to wait… but the best growers are patient.

        • C on March 22, 2020 at 2:24 pm

          No agent needed. Just flush, water I mean with warm water the first week then cold the next. Ne sure to ph water around 6.5.

      • Bud420 on May 7, 2020 at 1:56 pm

        Farmers do over fertilize with up-to 10 different additives. So NUTE build up in fruits vegetables etc. not the same comparison. Flush. What do you have to lose?

  3. Lansterdam Josh on January 11, 2019 at 9:28 am

    Flushing ONLY makes sense in soil if you have over fertilized. When you pass zero E.C. water through a nutrient rich medium, it dilutes the nutriments in the medium. Any other flushing is, indeed, pseudoscience. Or, rather, it isn’t science at all. It’s folklore and nonsense passed on by growers who have zero grasp of actual plant processes. When you feed your plant plain water, or water with supposed “flushing agents”, you are causing your plant to search frantically for the level of nutrients they have become accustomed to utilizing. They do this by taking up too much water, causing cell rupture due to the increase in osmotic pressure. That’s is science. And ruptured plant cells aren’t in your best interest. If you want quality product, learn to dry and cure properly. That’s where the white ash comes from, along with the smoothness. Don’t believe the hype.

    • Jack Herer on March 16, 2019 at 1:57 am

      You’re commenting on a Advanced Nutrients ad attempting to sell some special tailored magical flushing agents. Capitalism can be much more dangerous than folklore and nonsense, there are proper motives behind it’s manifestations such as this 😉

      • TeK-NiKaL on February 7, 2020 at 6:08 am

        It may be ad ad… but it doesn’t mean it’s wrong. Are you saying everything you use to grow was never advertised? I suppose you just was born with the knowledge of growing products? Don’t fool yourself…. word of mouth from your trusted buddy is three same exact thing as this ad. The one difference… your buddy likely isn’t a Botanist or Organic Chemist whose job it is to study these things. I swear by AN products. I’ve used many others and there is simply no comparison. I do feel that you don’t need to use all the suggested AN products they say to use throughout a grow. It’s simply overkill, but that doesn’t mean they don’t have knowledge about how our coveted plants grow. They are masters at the science. Don’t follow the words of others. Test it for yourself, be honest with yourself, follow the instructions, don’t cut corners and reap the rewards. Or just go back to smoking that sub-par bud that YOU think is the best.

    • Waylon on June 5, 2019 at 5:53 am

      It’s the nutrients in the stem and main stalk’ when hung upside down it leaches into the bud. Any grower can easily try a flushed plant vs reduced nutrient waters plant and see for themselves wich is better. Nature doesn’t flush the plant, but nature probably didn’t expect us to smoke it either.

      • growclean on January 30, 2020 at 8:57 am

        Nature also does not add nutrients to each watering.

    • Topsrite on November 22, 2019 at 8:13 am

      I been doing this for a long time, longer than a lot in this forum have been a live. You are 100% correct! I’ve tied flushing with plain water, distilled water, additives designed specifically for flushing and NOTHING has made any difference. Flushing in my opinion is a fallacy. When outdoors do you flush a field? Of course not. Please stop this nonsense. When stuff is grown in dirt, organically it does have the nice taste. When stuff is grown hydroponically you have stuff that kicks your ass! I prefer the latter, but enjoy both.

    • John on December 3, 2019 at 10:13 pm

      Bullsh_t. I’ve grown organic. I’ve grown non organic. flushing and not flushing. Temp/humidity controlled harvest and cure. The ONLY time it tastes like sh_t is when I havent flushed. Metallic, stingy, harsh, nasty bunk is what you’re telling everyone your product tastes like. Thanks, but no thanks.

  4. Art V. on February 1, 2019 at 1:06 pm

    Flushing is a myth.
    Anyone who has a basic understanding of biology and chemistry would know this.
    Plants don’t incorporate salts or extra nutrients within the plant matter.
    The roots will only absorb and transport the nutrients it needs.

    • jay on March 22, 2019 at 5:51 am

      are you a scientist? I think people should listen to the experts. but that’s my op

    • zylam on April 16, 2019 at 12:54 pm

      There are a few incorrect statements made here. As a botanist of 30 years, The cell’s vacuole contains water that stores waste products and nutrients. In our analogy, the vacuole is the equivalent of the warehouse. It increases tension in the cell walls by pressing against them, thus making the plant stiff. If the vacuoles don’t have enough tension, the plant wilts. Since vacuoles need water to create the tension, too little water will make your plant wilt.

      Acting as a repository, the vacuole also plays an important part in the plant’s fast responses to changes in water level. Potassium is moved from the vacuole to cell fluid when the stomata quickly closes as a response to too little water.

      The stomata can also have fast responses to light, temperature, and carbon dioxide levels, which means the plant is able to optimize photosynthesis and have self-defense against outside threats. If you see some of the bottom leaves of your marijuana plant start to turn yellow and die, don’t panic. In reality, this is a sign of an important process taking place. Like a factory, waste is produced in the cell processes. This waste is kept in the vacuole. When large amounts of waste need to be disposed of, it is deposited into the vacuoles of a leaf. This leaf is discarded by falling off the plant.

    • TJ on June 15, 2019 at 2:37 pm

      Hmm… does the human body work the same way?? (I don’t think so… ;))

    • Champs17x on June 29, 2019 at 8:39 pm

      Then why does the plant intake enough nutes two do kill itself?

      Serious question!! I’ve grown outdoors for 25+ years. Ready to harvest my first indoor crop!! Excited, really wanna get it right.

    • Scott T on July 31, 2019 at 4:34 am

      How do you explain nute burn if they only uptake what they need?

    • B woke on October 9, 2019 at 9:48 am

      If a plant only uptook the nutrients it needed, then you wouldn’t have nute burn.

    • growclean on January 30, 2020 at 9:48 am

      here is your scientific proof

      Most fruit- or yield-producing plants have a vascular system. The vascular system of the plant is what takes the nutrients and water around the plants via the roots (considered the start of the vascular system) and feeds the entire plant, including the leaves, to fuel the photosynthesis process. This, in turn, helps the fruits to develop along with the overall growth of the plant. The vascular system also transports starches, sugars, and nutrients absorbed by the plant around the whole structure, including the fruits.

      As the plant’s vascular system transports these vital sugar and nutrients around the plant, helping it to grow strong and healthy, it deposits the reserves it doesn’t need in certain parts of the plant. The main reserves are held within the stem and root ball. In a normal plant under normal conditions, these deposits are made up of natural, low-level chemical elements that are released when the plant needs them over the different stages of its lifecycle. In hydroponics, a controlled environment means there is an abundance of nutrients and chemicals being fed to the plant, so the buildup of these chemicals that are naturally stored in the plants tissues is not needed. It is vital to remove these chemicals before harvest. Not flushing the plants of these chemicals can leave your harvest unfit for human consumption.

      Within a plant’s vascular system are two main paths. The first path is the xylem, which is composed of four different cell structures. It is this path that transports water and dissolved nutrients from the roots throughout the plant and its organs. It also stores substances such as dissolved nutrients and water for later use. An easy way to remember it is to note that the xylem transports liquid for the plant to drink.

      The second path is called the phloem. The phloem is made from four different types of cell structures that transport the sugars made in the leaves throughout the plant and its organs. The plant can turn any of these unused sugars into starch and store them for later use. An easy way to remember this is to note that the phloem transports food for the plant to eat.

      The Flush Factor

      The first part of the flush process is to stop any further intake of nutrient elements via what the plant is drinking, through the xylem, and replace it with plain water. The second part is to flush out as many active chemical elements as possible that are already present in the plant’s vascular system. This is where the term ‘flushing’ comes from. The faster the plant is flushed of all active chemical elements, the faster it can move on to the next stage of the process. This is the key to the process.
      Water performs this process naturally in the wild over a much longer period of time. Hydroponics differs greatly as it uses constructed systems to get the most out of the plant in the shortest amount of time possible and to the best of its potential. So yes, while water works for this part of the process to a certain degree, a flushing agent will work faster. How? Well, it’s designed that way.

      While the whole process is complicated, the principle is simple. Think of water as a shape. For argument’s sake, let’s say water is an L shape. When this shape (the water molecule) is sent around the vascular system, it dilutes the active elements by picking off the chemical molecules. While the shape of the water molecule may seem ideal at first glance, it is not the best or the most effective shape.

      In comparison, let’s say that the flushing agent’s shape is an X. As you can see, this shape will be more effective. It’s basically four Ls back-to-back, so therefore should be four times as effective as the L shape. As this molecule moves around the plant’s vascular system, it will attract more chemical molecules than the L, thus diluting and flushing the active chemical elements out of the plant faster. As soon as the vascular system is not providing the plant with the nutrients it needs, it will start to release and use up the reserves it has stored previously. This is the next stage of the flushing process. Getting the plant to use its reserves faster will not only clean the plant of unwanted chemicals faster, it will also mature the produce faster.

  5. Don Chievesalot on February 1, 2019 at 3:25 pm

    Force feeding is the issue.. Let em take what the want make what they want and stay as long as they please. They will reward u in the end.

  6. Mr g on March 8, 2019 at 7:27 pm

    I’ve been flushing with water fr years and always had the same taste off different stranes! So i know there must b more to flushing, so i read up on its do’s and dnts, it was then i came across the final solution! Now we’re talking!

  7. Scrogzilla on March 14, 2019 at 5:27 pm

    I have smoked both flushed and non flushed product that I have been involved with, several times over the last 15 years,(trying different methods with different strains) and all the bud smoked s that was flushed was a lot more smoother than the buds that had not been flushed..
    Patients even noticed the difference and said that “this batch was smoother” or “this batch was harsher”..
    Im not a botanist but imo.. Flushed tastes better in the long run.. And the more fresh water that goes through the medium the better.. I have yet to find a grower that states that they over water at harvest and some put up to 80 litres through each of the plants over a week/two weeks.. And that includes soil growers.. At thw end of the day you can see the affect flushing has on the plant amd when the plant realised there are no hight levels of nutrient to imbibe we see the dark green leaves start to turn yellow and die off as the plant uses up the nitrogen left in them.. Buds swell.. Trichomes increase.. Buds dense up and start to try to save themselves and try to develop seeds.. As long as you dont let them go to far and chop before the plant has a chance to seed thwn yiu will find that flushing gives a better overall product.. Regardless of curing time..!!.. Whether you are able to cure for six months or only a couple of weeks..!!.. If your turn around is swift then you need to ensure you flush with a high amount of fresh water.. If you have six months to cure then you dont have to flush as hard.. But imo either way the more you flush.. The less chemical shit is left in the buds..
    However.. Organic feed is different..
    Ever had that weed that is dank and has like a slight/strong smell of either duck/chicken poop.. Or has that baby sick smell to it?? Yet it still smokes smooth and is nice.. Well there you have an organic product that may or may not have been flushed long enough coz obvs they are using soil mix mediums and haven’t flushed long enough.. But it still tastes nice.. The shitty chemicals we buy from the grow shops.. NEED TO BE FLUSHED…
    Otherwise it will taste like shit…. Thats my experience anyway.. Blessed are all those who enjoy and are enthusiastic about this plant.. X

  8. bryan occoner on March 16, 2019 at 4:31 pm

    flushing with water for at least 7 days in soil. you will notice a cleaner smoke . no blah ash clogged bong . no popping sounds. clean taste .
    what do you have to lose ? last 7 days there no longer growing there are always extra nutrients stored in the plants to use up.
    if you think flushing is a myth then flush a single plant and not the flush the other label them. and you will know what is what.
    for the flush solution that is another story. will say i wont waste my money and leave it at that. keep it green .

  9. jay on March 22, 2019 at 5:53 am

    can anyone say nutrient lockout, I can and it took a while before I could feed again. just saying

  10. Raymond Charles Buschow on March 22, 2019 at 1:15 pm

    I like Don’s Philosophy. I simply don’t feed them the last week of flower.

  11. Archaic on March 25, 2019 at 2:22 pm

    Explain to me how a plant “uses up” phosphorus and potassium? I’m really curious as to how marijuana growers can violate the law of conservation of mass but tomato and corn growers have never been able to. Please take a damned botany class before you spout out this fiction next time.

    • TeK-NiKaL on February 7, 2020 at 6:23 am

      Please stop comparing marijuana to food we eat. I know they say tomatoes grow like marijuana but there is one major difference. We’re aren’t smoking tomatoes!! The lung tissue is a completely different biological system than our intestines. The lungs can be scarred and burned by smoking harsh chemicals. How do you know what those leftover chemicals in the foods we eat are doing to your insides? On the other hand when you smoke harsh buds you can feel that. The difference in opinion comes from the simple fact that we are all slightly different when it comes to sensitivities in our bodies. Those with young lungs or genetics may not mind or notice a harsh smoke. The next guy with sensitive lungs or 25 years of smoking under their belt may feel the difference. Flushing with an agent is a proven thing believe it or not . In the end you’ll do what you want… but growers who will settle for nothing but the best know the truth.

  12. Kevin on April 7, 2019 at 10:37 am

    I can’t help feeling skeptical about this article, as it sort of claims to know the science behind what they’re claiming yet doesn’t even provide any proof that it works besides the “fact” that “most experienced cultivators” use this technique. Careful of this website as much of the information is correct but there are some “facts” interspersed throughout that have little science if at all backing it up, and if there is the science out there they don’t provide it. Flushing may very well be valid but we don’t really know for sure, and there are plenty of people out there claiming it is not necessary. The truth is usually more complicated than that unfortunately.

  13. Vincent on April 9, 2019 at 5:34 pm

    The vast majority of “scientists” once thought the earth was the center of the universe, that arsenic was good medicine, and that disease was caused by an imbalance of humors.
    Show me an actual controlled experiment. Someone.

  14. Huff on May 27, 2019 at 11:36 am

    If you only wayer when the soil is dry you wont need to flush period. Do I believe you should stops nutes around 2 weeks before harvest? Yes. I dont allow my soil or plants to build up extra nutes. Ive done both ways and I like only watering when soil is dry. Before I water each time and dig down about 3 inches into the soil. If its damp I leave it alone

    • Ben on September 28, 2019 at 9:11 am

      Exactly, IDK where these people get off calling flushing pseudoscience..there is proven science & many proven studies about flushing & letting the plant use up what nutrients are stored in it. You can taste the chemicals in a plant that was fed bottle nutes & never flushed, not to mention the harsh taste in your throat that makes you cough & the black ash that doesn’t burn smooth at all. Drying & curing can help fix it but it is still very noticeable to someone like me who is a weed snob lol

  15. Curt Richardson on June 2, 2019 at 11:16 am

    The flat Earth and anti-vaccine people are the ones who don’t rinse the medium. People will always reject good advice. Nothing will change their minds.

    • Tbone on June 24, 2019 at 7:00 am


    • Big Al Stockton CA Delta on October 1, 2019 at 2:05 am

      One word organic. If you are not than you are a dumbass you’re poisoning the entire world. Same as if you eat meat or dairy you destroy the environment and the air we breath. ORGANIC NON GMO PLANT POWER is the only way. No flush pure and natural the way it is supposed to be

  16. Prometheus on June 12, 2019 at 1:21 pm

    Educate yourself on plant biology. The idea of flushing only came about because of closet weed growers who think they have a grasp on anything that grows without any actual knowledge. Until you can properly explain what nutrients the plants takes up, how they do it, why they do it and when (without googling it) then you have no idea what’s going on. Farmers don’t flush their corn crops, strawberries etc the last few weeks. There to this day is still absolutely zero proof flushing the plant helps with harvest, taste, yields whatsoever. Unless you have scientific reports to supply, like the rest of the know it all potheads, sit down and listen to experts. You are a follower not a leader

    • B Woke on October 9, 2019 at 9:58 am

      You say this when I, as well as countless other growers, professional and personal have actually taken the time and done a side-by-side study.

      This is what I did. Same mother plant with 6 clones in outdoor soil. Indica dominate hybrid. 3 flushed 2 weeks prior to harvest, 3 given nutes until 3 days prior to harvest.

      After harvest, dried 7 days, cured 6 weeks. Flushed plants slightly denser, smoother taste, better smell….just all around better product.

      No myth, hype or bull.

    • John on December 3, 2019 at 10:24 pm

      We don’t smoke corn or strawberries, we eat them. Different topic altogether.
      “There to this day is still absolutely zero proof flushing the plant helps with harvest, taste, yields whatsoever.” Hahahaha….. Zero proof….. that’s really kinda like saying there’s zero proof vitamin C does anything good for our bodies. I really feel sorry for the people who take grow or harvest advice from you.

    • Canuckgrowz on December 27, 2019 at 2:59 pm

      @Prometheus. They sure do The seasonal grow cycle of corn is dependent on rain to grow and to be flushed in the early fall.

    • TeK-NiKaL on February 7, 2020 at 6:41 am

      And you are simply wrong bro. All this hating on flushing has wrecked the industry. There are so many poor quality buds on the market now because people are lazy and don’t flush and believe the naysayers. And make sure you’re using RO water. So called purified water isn’t that pure. If you want the best use the best.

      • C on March 22, 2020 at 2:51 pm

        Flushing yes purified water no. Straight tap left out 24 hours then ph to 6.5-7. You just had to take it a little too far with the purified. Ever drink rain water? There is nothing pure about it.

  17. Linda Truax on July 13, 2019 at 6:49 am

    Loop Would like to know as much as possible about flushing vs non-flushing. And when you should begin …..and does hanging them upside down really help….and what about growing inside vs outside in northern state during the warmer weather.

    • C on March 22, 2020 at 2:57 pm

      No need to hang upside down, makes better sense to cut each branch at main stem and just hang them, or like me I have dry racks and I just throw branch with buds in those and get to full manicure asap before it dries too much, then just let clean buds dry on racks proper length 7-14 days, at proper temp and humidity 65-75 degrees 30-50%. Cure as long as possible but that’s rarely a option.

  18. Matt Hutchins on July 17, 2019 at 11:37 am

    More perpetuation of unscientific myths and outright lies. You should be ashamed. Vitriole like this is why cannabis growers are mocked in the horticulture world. NO serious grower flushes for 2 weeks. Only those who still believe in old wives tales like hanging your plants allows the resin to run down to the buds, and splitting stems increases potency.

    The ONLY thing you can “flush” out of your plant is the old, nasty tasting water which can be replaced with fresh clean water. THAT’S ALL. This can be accomplished in just a few days AFTER plants are already ready to be harvested.

    The most important factor influencing taste and burn quality(aside from a proper cure) are RESIDUAL SUGARS. Sugars burn harsh, black, and taste terrible like a burnt marshmallow. Again a few days without food is enough to allow the plant to burn it’s sugar reserves. You really want to ruin you crop? Bombard it with bloom boosters, carboloaders, and commercial flushing agents full of sugar.

    If your plants arent green and healthy when you harvest, then YOU’RE DOING IT WRONG. PERIOD. I’ve judged multiple Cannabis Cups over the last 30 years and the best tasting cannabis I’ve ever had was grown by BushyOlderGrower. His plants are dark green and 100% healthy at harvest. His flower disappears into white ash when burned.

    ” ‘Nuff said.”

  19. Jim on August 6, 2019 at 5:51 am

    I just want some hard scientific facts. You know evidence. The human mind can tell itself anything and believe it. Anecdotal is not the kind of eveidence science relies on. Why dont you get your team of science minors to do a study and prove it? You could test everything and stop the actual debate.

  20. Big Buds on September 7, 2019 at 7:36 pm

    Sorry I have the best plants and I grow outside and only use water no chemicals. I don’t care who or what said it. Once you use chemicals on your plants. It is absorbed into the entire plant. It is now in that plant. You can’t flush it out. The chemical are in there till harvest. Then people smoke the chemical. It truly can’t be good for you. So my point being is for a healthy smoke and safe smoke. Don’t use chemical. They will grow wonderful with just water. I am proof of that. People mass produce weed and go for quantity not quality and healthy weed.

  21. afdas on September 9, 2019 at 10:55 am

    and not one person has done a side by side or offered any evidence other than a bunch of stoner talk

  22. Archaic on September 15, 2019 at 10:56 am

    This is one of the most misleading pile of poo articles I’ve ever read. Flushing is a myth that is unsupported by any modern horticultural science. Here, have some real science:

    • Zen on May 4, 2020 at 10:35 pm

      @Archaic. Finally someone provided some real evidence. Flushing is just a bs waste of time and some people who did try to see the difference themselves were just more lenient with the fact that they thought just because they “flushed” it actually did something. Flushing is bs don’t waste your time

  23. Ryan on September 23, 2019 at 1:09 pm

    What if your using fox farm potting soil not coco? How long should i flush for?

  24. Cookiecat on September 30, 2019 at 7:51 am

    Flush to remove nitrogen – with- pk boost… then dry and cure to oxidise remaining potassium and phosphorus…. just my 2p…

  25. Jsmoke on October 2, 2019 at 4:20 am

    Farmers don’t fertilize up till harvest.

    • C on March 22, 2020 at 3:06 pm

      Thats because farmers use time release fertilizers and manure.

  26. Jim on October 2, 2019 at 2:04 pm

    So a little truth and a whole lot of crap and speculation. The harsh taste and black ash is almost always a nitrogen issue. Nitrogen is water soluble and will leech out of mediums like soil with plain water where elements like phosphorus do not, but this is a huge topic in itself. Too much bad info on this, people grow a certain way and notice what produces a better product under specific circumstances then come up with an unscientific reason for why this occurs then another tries the same practice under a different set of circumstances and has a negative effect. N is an element that can translocate within the plant and pot normally goes N deficient towards the end of its life cycle hence the yellowing leaves starting from the bottom. To make this short most soil growers would probably benefit from flushing to allow the denitrification process while hydro clay ball growers can just reduce N towards the end and end up just fine. Ill also mention that because plants don’t suck in nutrients its pushed in via osmosis they certainly don’t just take in what they need but again that’s another huge topic.

    • C on March 22, 2020 at 3:11 pm

      Fox farm recommends stopping N at week 6 on a 8-9 week strain so less or no watering only near end is needed. One doesn’t need to flush P or K out because that naturally processes itself during dry. I still water only last week so maybe two or three water only feeds at end.

  27. warren on October 24, 2019 at 10:54 am

    after 2 weeks of flushing can plants be harvbested while soil is still wet or damp

    • C on March 22, 2020 at 3:13 pm

      Not bone dry not wet, somewhere in between.

  28. Shortbritches on October 25, 2019 at 10:36 am

    I agree with me Prometheus ,I have grown for 52 years almost 95% of the time organically in soil ,I have tried flushing on numerous occasions and I can not tell the difference .maybe if you grow using chemical fertilizers??? But if grown really organically in dirt I do not see a reason to flush it is just a waste of time and $$ if using a flushing agent.,

    • C on March 22, 2020 at 3:16 pm

      Look at supersoils. They feed til end, no flushing, mostly or all organic. So I agree with you. Only use of full or hybrid synthetic nutes should require any flushing.

  29. Farrah Kellington on November 30, 2019 at 8:37 am

    Ever tried smoking an I flush plant… smoulders and doesn’t burn!! That’s all the proof you need!

  30. Keith on December 5, 2019 at 5:49 am

    Flushing is a hoax. No commercial grower of foods does this.
    Also, the removal of toxins and nutrients idea is bogus. If there is a build up of potassium in your plant, somehow, how does flushing remove this? Potassium is a solid. Where does it go? Does it jump off the leaves? Trav back down the root system, into the soil? Evaporate? No. No. No. No.
    Flushing is a myth. Don’t waste your time.

    • C on March 22, 2020 at 3:19 pm

      Nitrogen is really the only one that should be flushed out, but that can be obtained by not feeding heavy N few weeks before cut. Maybe a water only feed or two. P and K are naturally released and transformed when drying.

  31. Bill on February 19, 2020 at 7:56 pm

    I don’t flush, did a test with some of snobby friends. Told them they were getting 2 different plants, one flushed, one not. It was the same bud from a non flushed plant. They said the “flushed” plant was smoother than the non flushed :).

    The plant will do whatever it can to keep the nutrients in the bud. Unless you let the flower wilt, it will have the same amounts of nutrients feed or not.

    Be honest, do this experiment yourself, you won’t be disappointed.

  32. Kingkong4293 on April 4, 2020 at 9:04 am

    I’m a new grower and I started my plants off on the 12 12 cycle right off the back is that ok or am I robbing them of nutrients? I have 4 plants 3 are about 11 weeks old and one is about 8 they are all flowering good but the seeds I have I’ve collected over the years so there are both regular and hydro seeds I have but cant tell the difference in them so I’m kinda winging it which is bad but im using mushroom dirt with full spectrum lights and I’m trying to find out when is the best time to harvest because I dont have any tools to look at the tricone color I can only really see the pistils some are white and reddish orange any advice?

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