Flushing outdoor organic soil prior to harvest

I’m growing outdoors in fabric pots using amended soil and then top dressed with various meals and amendments throughout veg and bloom. Is it necessary or even possible to flush these nutes prior to harvest? Some of the meals like fish bone and feather meal have non water soluble components, which are slow release, so how is it even possible to flush these out?


Was having this EXACT discussion yesterday. Will bring in the vets. :joy::rofl:

@Hogmaster @Countryboyjvd1971 care to elaborate? @1BigFella @Willd are outside gurus as well.

But as i understood. They feed hard entire grow. (Believe one uses bottles nutes tho) And towards the end of the grow. Instead of flushing they use pure pH’d water a couple of weeks. To allow the plant to burn up all the available nutes herself.

Sorry if i got it confused. Thats why i tagged for confirmation or any other info. :+1:t5:

U gotta pic of the girls @Mmarg

That’s right the plant will start eating all the leafs And use that energy to put into the flowers no need to waste extra nutrients when you got everything you need already there week or so before harvest


That pretty much what i do as well
As we discussed ill fed full streaght once a week or more if needed
Once plantnis old enough to feed
Ill stopp feeding two to three weeks before I harvest allowing plant to use nutrients in soil
And just ph water that whole time as needed

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Thanks fellas. I ready waaaaay to often on this site n would rather he get his info straight from the horses mouth so to speak. :pray:t5:


If you wish to flush the pot just run 5 x water to pot size so five gallon pot youd want to flush 25 gallons of ph water through the pot about a week before harvest
I personally don’t flush

Use a product containing Saponin to flush. You can wait till 2 weeks before harvest to use it.

Saponin? Oooo new lit! Do tell

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Fox Farms makes a thing called Sledgehammer… main ingredient is Saponin.

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All these techniques work. I use pure coco so my flush is just to water for a couple of weeks with pHed water. That washes out any nutes very well, and you can see the plant consuming the fans immediately. By the time I harvest, I hardly have any fan leaves left.

I grow directly in the ground & use minimal fertilizer.

Dirt in a 24” wide hole is enough to buffer any variance in pH, IMO

I lay off my bloom nutes 7-10 days prior to harvest & withhold H2O.

I grew for a couple of seasons not using Cal mag supplements and I honestly don’t see any difference. Same with the silica.
But if you’ve been feeding with metal based nutes, you definitely want to flush before withholding water at the very end.

Almost everything my plants need trace mineral wise, is directly provided by the soil my yard is made of.

The 5-1-1 fish based veg nutes weekly & 0-10-10 fish based bloom nutes + KoolBloom every 2-3 weeks has worked well in the past.

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Fish based bloom!!! That i need to look into! I thought alaska was all vegging nutes :joy::joy: my girls love them btw. I need a ppm meter…

I’m using a hybrid of fabric pots with a sizable hole in the bottom that allows the tap root to grow into the underlying soil. I’ve used an amended coco based “soil” and am top dressing the nutes(for 120 gallons total:

4.5 c kelp meal

Veg: 2c feather meal 2c high nitro bat guano 1c fish bone meal, 2c langbeinite

Flower: 4c fish bone meal 4c seabird guano 1c feather meal 1c high nitro bat guano, 2c langbeinite

Gypsum 6 c)

so I’m not really sure what percentage of the roots are within the pot to absorb what I’m giving them. and what percentage has grown below. The plants are 5-8 feet tall so I assume that tap root goes pretty far down. Any metals in what I’m feeding?

Nope. Doesn’t look like it. I didn’t see the part about fish, bone, and blood meal. not sure how to “flush” those components since as you mention have non water soluble properties.

Alaska makes one called Morebloom

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