How To Properly Flush Cannabis Plants
How To Properly Flush Cannabis Plants
How To Properly Flush Cannabis Plants
Professor DeBacco
Thesis
Stemeroff, J. (2017). Irrigation management strategies for medical cannabis in controlled environments (Doctoral dissertation).
https://atrium.lib.uoguelph.ca/xmlui/bitstream/handle/10214/12125/Stemeroff_Jonathan_201712_Msc_with_erratum.pdf?sequence=8&isAllowed=y
https://atrium.lib.uoguelph.ca/xmlui/handle/10214/12125
Flushing in General
Typically at the end of the flowering cycle prior to harvest the root zone of cannabis plants will be watered with plain water that does not contain any additives such as fertilizer.
Fertigated water is water that contains nutrients.
Depending on the substrate the plant is being grown in will dictate the duration of the flushing period.
Flushing Specifics in Study
Flushing occurred over the last two weeks of production when the nutrient solution was replaced with clear water during routine irrigation events.
Another flushing method was to apply an additional 10L of water without any fertilizer to the plant over two irrigation events at the start of the two-week period of clear water irrigation.
Study Treatments
1)Control Treatment with 10L initial flush completed twice and non-fertigated water until harvest
2)Control Treatment without 10L initial flush and non-fertigated water until harvest
3)Mild-Stress Treatment with non-fertigated water until harvest
4)Mild-Stress Treatment with fertigated water until harvest
5)Moderate-Stress Treatment with non-fertigated water until harvest
6)Moderate-Stress Treatment with fertigated water until harvest
Bud Dry Yield for Flower
Note that there was determined to be no significant difference in the following…
Whole Plant Dry Yield for Flower Cycle 1
Bud Dry Yield for Flower Cycle 3
THC Percent by Mass for Flower
Note that there was determined to be no significant difference in the following…
THC Percent by Mass for Flower Cycle 2
THC Percentage by Mass for Flower Cycle 3
Elemental Analysis of Buds for Three Flowering Cycles
Flower cycle 1 elemental analysis of bud after flushing. Shows the percent concentration by mass of the nutrients within the dried bud. Error bars represent the standard error (+/-SE). There are no significant differences between any of the treatments analyzed using ANOVA at significance of p less than 0.05.
Water Reduction from Treatments
Moderate-stress treatment was able to reduce water use by over 45%
Mild-stress treatment was able to reduce use by 25%.
Removing the 10L initial flush was able to reduce water use by 22.9%.
General Summary
By reducing the irrigation frequency there were large reductions in water use with little impact on overall yield and THC concentrations.
Removing the two-time 10L flush reduced water use in the same treatment without the two-time 10L flush by 22.9% with the non-significant impacts on final dry yield and THC concentrations
Another option for reducing water use is to examine flushing practices.
A significant reduction in water use for irrigation will lead to a significant reduction in humidity with which the air handling system must contend.
Flushing Nutrients from Substrate
The practice of flushing is a current common industry practice but there is no evidence in published literature of its effectiveness in reducing nutrient concentrations within the bud or even whether or not this is a desirable result.
This result showed that the intended purpose of flushing to reduce nutrient concentrations within the bud has no effect.
This data shows that for the last two weeks of the flower cycle for cannabis, it was possible to use no fertilizer water for irrigation with no significant impact on yield while saving input costs on fertilizer
Applies to Both Indoor and Outdoor Growing
While there are differences for each growing environment, the same general concept applies.
Specifics for each are provided in other videos, if you want to know some more details to best fit your growing conditions.
Link to Lecture Slides: https://drive.google.com/file/d/1GVVLegxE67t4fn2eevnYX95mmX0corpV/view?usp=sharing
420 Magazine Source Content by Slide Title:
Flushing Specifics in Study
https://www.420magazine.com/community/gallery/flush-feed-all-in-one-go-step-4.1748734/
Applies to Both Indoor and Outdoor Growing
https://www.420magazine.com/community/gallery/20190713_094022-clearing-the-ions-jpg.1695699/
https://www.420magazine.com/community/gallery/20210620_185218-jpg.1831763/
*Due to the description character limit the full work cited for “How To Properly Flush Cannabis Plants” can be viewed at… https://drive.google.com/file/d/10N43BSrf0-MgwG4nNTLhq6FpyqaC-g_h/view?usp=sharing
One of the conclusions of the study is that flushing produces no effect on the bud. I am curious, however, if it is still beneficial to the soil/plant itself in veg when you have nutrient buildup/pH issues. I’d appreciate any feedback.
So amazing work, my friend, it’s so professional!!
This is the most educational series on canabas anywhere. I am a new grower and using hydroponics 5 gal. Bucket system. When i flush should i just run pure water thru my system for a couple of days or run 2 runs of plain water back to back.
Most Excellent! Another well put together presentation with actual data to back up. I’ve been using Dr. Wedryk et al. from RXGreen and a few other papers for people to read over, but hey, who reads anymore? Now there is another 1st pick for me, as some might watch a video over reading dissertations and data summaries haha. Another great job bud. With slide links and lecture resource citations too! That deserves a Bill and Ted Air Guitar "Excellent!!!!" haha.
Most interesting would be the pot size?! 😀
Why not Just change the PH of Soil so the Plant cant absorbe any nutrians?
i seen it was you and thumbs up instantly, on top of the fact the title is what i exactly searched up
good demonstrations btw gracias
Love your videos dude
So according to this, there it really no benefit to flushing the plant?
I’ve had some weed be hardship and black ash. Do you think I should let it cure longer?
Doesn’t that just water down taste and smell? That it shouldn’t need the flush unless your providing too much nutrients. Look at berries and apples of what happens with wet years. Like this year bumper crops and not as good of taste. Where the drier years yield smaller fruits with better taste. These can be seen in the brix. Does flushing dilute taste and smell along with brix levels? When is the best time to harvest for peak terps not peak thc?
I’ve always been told buds from flushed plants will burn more cleanly than non-flushed plants, i.e. less left over residue, more white ash. Truth/myth? Is this even desirable if so?
Thought this was all bro science😂.
This video isn’t exactly HOW to flush but rather a boring class lecture in flushing.
This is very great information.
Do u have a hydro flush
So glad i watch all these videos. I learn so much
amazing!
Question: Does un-flushed cure stronger than flushed?
Flashing always sounded like some bullshit. Just don’t overfeed and your plants will be fine
Excellent, great information,im impatiently waiting threw my flushes
So while flushing may have no effect on THC levels and concentrations but IT WILL AFFECT TASTE GREATLY!
Good to see some actual scientific evidence with data points to back this up. Always thought that flushing didn’t make much sense
Great!!
Thx!
When flushing should you used pH water? if so, why?
Stoner science – no need to flush plants before harvest – waste of water.
Finally
When flushing or just switching to plain water at the end of flower cycle what is the best ph to have your water? 6.7? 7.0?
I’m close to harvest and very confused 🤦♂️is this a new cannabis doctrine or is just the simple truth? I mean we all know flush is better and all of sudden this info was like a heavy face slap 🤔need help very very confused
Important new info, results are not what I expected but it’s good news.