To Flush, or Not to Flush? That Is The Question!
What Is Flushing?
First, let's start with the basics. If you're not familiar with the concept of "Flushing", in the context of growing your plants indoors, it refers to the process of irrigating the plant(s) with plain purified water (no nutrients or additives!) for a specific period of time prior to harvesting. It involves using a significant amount of water to flush out any accumulated nutrients, salts, and other substances from the plant's root zone.
The point of flushing is to remove excess nutrients and minerals that may have built up in the plant's tissues and root system during the cultivation process. By providing only plain water without any additional nutrients, growers aim to "flush out" or leach away any remaining residues. This practice is particularly important during the final days/week of the plant's life cycle, leading up to harvesting.
The concept is two-fold:
By flushing out nutrients and additives, there will be nothing left in the soil for the plant to uptake in its final days; and
The plant, starving for food, will "use up" said nutrients that exist within its own structure, such as any available compounds within its leaves and stems. This is sort of analogous to the way humans will lose weight by restricting caloric intake to force the body to "use up" the glucose energy stored in the body in the form of fat.
So flushing will concurrently stop the plant for taking in more nutrients, and cause it to deplete any remaining within the plant.
The Great Debate - Myth or Reality?
There's a great debate about flushing. Some folks will tell you that you absolutely MUST flush, and all the benefits thereof. Others will tell you that it makes NO DIFFERENCE AT ALL and that it's all just hogwash.
How confusing, right?!
Ultimately, we suggest you test it yourself and develop your own preference over time - that's the real answer. But let's delve into the pros and cons, and hear our opinions on the matter.
Why To Flush
There are a few reasons why flushing is considered important for indoor cultivation:
Improves taste and aroma: Flushing helps to improve the flavor and aroma profile of the harvested buds. By removing excess nutrients, particularly salts, the plant can produce a cleaner, smoother smoke or a more flavorful and aromatic end product.
Reduces harshness: Excess nutrients left in the plant's tissues can contribute to a harsh smoking experience. Flushing helps to minimize the harshness by eliminating these residual salts and substances. In this author's own experience, I can typically tell when a product has been flushed or not by how harsh it hits in the back of the throat. I swear I can tell a difference in the smoothness of the end result, so I'm in the pro-flush camp.
Promotes a cleaner burn: Accumulated nutrients and minerals can affect the combustion process when smoking cannabis. Flushing helps to create a smoother burn, leading to a more enjoyable smoking experience. Again, I personally can attest to this. Some of the minerals in the soil, that the plant absolutely NEEDS to grow, are phosphorous and magnesium. These are flammable metals used in fire-starter kits and flares because they burn bright. When I light a bowl and it goes "snap, crackle, pop!" like my cereal, I know the bud still has phosphorus or magnesium in it. It's been pretty clear to me that when I flush - no snap, crackle, pop. Now, I don't necessarily always get the snap, crackle and pop with non-flushed bud (sometimes the "effect" of flushing just happens anyway in the natural growth lifecycle of the plant), but I can tell you that any time I DO get the snap, crackle and pop the bud in question was not flushed -- I've seen a direct correlation myself.
Now, those are the reasons for flushing at end-of-life, which is what most of the debate centers around. There are also times mid-grow, that some people might suggest flushing, and these are for very different reasons and are generally NOT debated (i.e. there's consensus for these cases):
Preventing nutrient lockout: In some cases, an excessive accumulation of nutrients can interfere with nutrient uptake in the plant's roots. Flushing can help prevent nutrient lockout, allowing the plant to properly absorb essential elements during the final stages of growth.
Fixing PH problems in the soil: When PH goes out of whack, it can create nutrient lock-out, similar to #1 above. And for the same reason, you can flush the soil to get a "reset" and get PH values back on track.
- Mitigating Over-Feeding: If you over-fed the plant too much Nitrogen or Cal-Mag and the plant is getting burnt, sometimes you need to flush the soil to flush out the abundance of extra nutrients so you don't completely fry the plant. It's another form of "resetting."
Some Final Thoughts About Flushing
It's important to note that flushing practices may vary depending on the specific growing techniques, medium used, the reason for flushing, and individual preferences. Some growers may choose to implement a longer flush period, while others may opt for a shorter duration. Monitoring the plants closely and observing their response can help determine the optimal flushing period for a particular cultivation setup.
Now that all said, this blog is sitting at our website, so while most of the article was a high-level, general overview that could apply to growing in tents, greenhouses, and more, as well as both photoperiod and autoflower seeds, we'd like to close with a few comments specific to growing in either The Armoire or the ATS-42 Grow Tent Kit, both of which use our own "Easy Grow + High Yield" protocol.
First, we have this very specific grow protocol we've created for growing in The Armoire (and extended to our tent kit). All folks growing in The Armoire are coached on our protocol. It can seem very simple and straightforward at first when we GIVE you the answers to the exam, so to speak - "just do this and this." But the more you use it and the more you learn about growing in general, the more you'll start to appreciate all the little nuances focused around it and why we do what we do. For instance, we almost never have to worry about flushing mid-grow because if you followed our protocol you shouldn't have any issues with nutrient over-feeding or soil PH values. Our protocol is designed to circumvent that in the first place! So this is not even mentioned.
And, this is also why we provide THREE options for flushing in our protocol: don't bother; short format; and long format.
The first option (just don't bother) is self explanatory. You may find you're perfectly happy with the result and want to skip the extra few days, and the hassle. You might also, depending upon your specific circumstances, decide the tradeoff is worth taking. For instance, if your physical mobility is severely restricted and you need assistance getting the plant out of The Amoire, you may make the tradeoff of skipping this step to accommodate your personal physical needs/requirements.
Assuming you can flush and want to, we have a short version and a longer version. The longer version was part of our original protocol. It's the most thorough approach, but requires removing the plant from the cabinet TWICE and flushing over several days.
The short form version was created as a "happy medium" for folks who definitely wanted to flush, but had logistical issues with the long form version -- either physically getting the plant in/out of the cabinet ("...I can do it once, but not twice...") or scheduling issues ("...I'm going on vacation and the plant is done. I want it finished by Tuesday, before I leave...") So the short version compresses the effort into a faster time frame, splitting the difference. Not quite as thorough as the full flush, but it's a lot better than none at all.
As noted above, I personally find that I can tell a difference when I flush versus when I don't, but it's a relative difference: "A" grade versus "A+". My philosophy is that I just invested 2 to 3 months growing this plant, so I might as well give it the last few days to cap it off and do it right. So I typically do the full, long format flush. But sometimes, depending upon my travel schedule, etc., I might cut corners and just skip the flush and consider bringing my "A Game" good enough.