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Flushing Cannabis P...
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Flushing Cannabis Plants

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The Term flushing ALWAYS starts a disagreement in the Cannabis space, its more of a personal preference then anything. The definition of it seems to change based on the grower. HERE is what I think of when I hear "Flushing"

1) Pre-Harvest Flush

Pre-harvest flushing is typically used when growing with Synthetics, this style will force plants to use up the nutrients stored within themselves and limit the uptake of new nutrients. This should be done between a week and 10 days before harvest, if you start flushing earlier you can be doing more harm then good as the final 3 weeks of Flower are important for Potency, Terp profiles and overall Resin contents. Some growers believe this will eliminate "black ash, or harsh smoke" (White ash DOES NOT mean Quality Cannabis, Higher resinous strains will appear black over white).

2) Repair Flush (Lockout)

This style of "flushing" is used when you are needing to fix a plant issue! A deficiency in plants is not always due to a lack of nutrients but can be because of a single nutrient causing its system to become unbalanced. Overfeeding a plant seems to be a huge issue with first time growers, the plant will absorb what is needed to sustain a healthy life but as the access nutrients sit in the soil you will need to "flush" those out before it leads to a build-up of unnecessary nutrients. 

A good rule of thumb when dealing with a serious nutrient lockout issue, is to flush the plants and add fresh ph'ed water at half strength of nutrients. 

3) Transitional Flush

Cannabis has different nutrient requirements depending on what growing stage it is in. flushing out the veg nutrients is a good way to reset soil while a plant is transitioning into the flower stage. This is considered more of a preventative flush. It's not required, but can be a benefit from to start fresh between stages.


What doesn't happen, 

Feeding ONLY Water for weeks before Harvest DOES NOT and WILL NOT remove the nutrients already in the plants system. You are ONLY removing the excess in the Media to prevent further uptake. If you have a problems with overfeeding in the final stages of flower and notice your plant is becoming locked out. This means your media is hitting high EC values, and it is definitely smart to use a "Repair Flush (Lockout)" to prevent any further uptake. 

Flushing Outdoor plants that are directly planted in the Earth,

Your plants root system is SO deep into the earth adding Water isn't gonna 100% limit the nutrient uptake. The plant has the full earth to keep stretching those roots! 

Flushing Potted Organics, 

IMO you are just killing your soil and should only be done in the final few days IF you are wanting to reuse your soil. It is best to start off a grow with a lower EC media. The more popular ways of growing Organic cannabis is using slow releasing nutrients.. So even if you are trying to "flush" you are essentially just overfeeding. 

Products that help with breaking down Nutrients,

Magnesium (Epsom Salts)
Humic / Fulvic Acid
From my understanding the only way to Truly removed all Nutrients in the Media is to Flush 5-10 times the amount of water compared to Pot Size (depending on media). (5 Gallons, roughly 25-50 Gallons)

?Cannabis Live Grow :

Posted : 02/04/2022 11:25 am