Green gene does in fact use 4g part a, with 2g part b, no epsom. HIS theory is that there is magnesium sulfate in small amount in part a, so by increasing to 4 g a gallon is adequate enough, because HE never has magnesium issues. My thing is that jr peters does sell the epsom, they know every1 is buying it for cheap at a Walgreens, walmart etc, but they still recommend it at .99 grams per gallon. People love to tweak these recipes to think there way is the best way. Imo it is best to follow the standard 3.79, 2.5, .99 gram per gallon. Its tried and true. Green gene def knows his stuff but bc he says its not needed, does not mean it is 100% not needed. To each there own.
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Using 4/2/0 during flowering looks interesting to me. I did some math and calculated the NPK for all the different blends Iāve seen. All of them are actually very close. I need to look at the micros in part A more, but 4/2 is one Iām likely to try.
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Lol. I posted about 4/2 right below you and had only read about halfway through the thread to OGās post I replied to.
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That is something worth sharing. I have screenshots from a Greengenes video but do not know how to calculate them myself.
Also, I found this in an article in Cannabisbusinesstimes
What Are the Optimal Rates for Magnesium in Cannabis?
A recent study determined a range that optimizes plant growth and flower production.
Magnesium Fertility Rates
Given the results of our research, we believe that the optimal fertilization range of Mg for cannabis is between 50 and 75 ppm Mg provided throughout the production cycle, which is slightly higher than most other crops, which average between 25 and 50 ppm Mg. At these rates, plants were significantly larger in total plant above-ground dry weights when compared to the plants grown at 0 ppm Mg. Researchers controlled for Mg from other sources, including irrigation water. The leaf tissue concentration had an increased accumulation for all rates, with the highest rate resulting in the highest concentration of Mg (100 ppm Mg). Magnesium also has a large impact on the flower production of cannabis, meaning growers experiencing Mg deficiency could see a large negative impact on profits. However, providing Mg at the recommended rates and above resulted in similar cannabinoid concentrations. Therefore, based on our research, there is not any benefit of providing more than 75 ppm Mg to the plant.
This is one of the screen shots.
I believe the 2nd column must be the 4/2 formula you are referring to
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Not sure how accurate that is. GH Lucas 8/16 is closer to 1000ppm I believe 
@Outlaw Take a look at this.
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Thatās absolutely awesome. Thanks for bringing it to my attention. Me, my notebook and calculator thank you very much.
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I have that same screen saved. Good to know that kind of stuff. Someone can correct me if my math is wrong. I got these reduced as much as possible.
3.6/2.4/1.2 = 1.25-1-2.16
3.79/2.52/0.99 = 1.25-1-2.16
2/2.7/2/1.2 = 1-1.69-1.82
4/2/0 = 1.04-1-2.08
3.8/2.2/1.2 = 1.14-1-2.17
I had a new topic written and never posted it. I thought it was generally accepted that you needed something like 3-1-1 for veg, early and mid bloom 1-3-2 and maybe 0-3-3 late in flowering. Numbers there are debatable but point is I thought you needed very different NPK for each stage. With these blends of Jackās theyāre all pretty close.
*I basically did weighted percents with the NPKs for part A, B and MKP. Also noteworthy that Epsom salt is 0-0-0 so no matter how much of it you use it doesnāt change the NPK of your nutrient solution.
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I came across a conversation about using nutrients at a lower level and building up to flower what was being said made sense as long as itās being done rite. Thereās alot of good growers that use a reduced nutrient schedule that increases in the different plant stages and have success. Iām the first one to admit I donāt know shizz about nutrients and the numbers but Iām not afraid to experiment as long as it makes sense to me. What is rite what is wrong as long as itās being done rite thatās the fun of growing for me.
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Thanks for the explanation. Iāve wondered why people do that since Jacks is designed to use full strength start to finish. Thatās one of the attractions of the product.
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I agree! Iāve alwayys used jacks full strength
With great results. After thinking about the reduced nutrient program it interferes with bloom im not going to go down that road so i decided to go 80% mix then use bloom at full strength and finish 321 at full strength.
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The only thing I do different is the first shot of Jacks when the plant is big enough, I do it at 50% just to make sure I am not overfeeding if the soil itself is still giving a lot to the plant. Then, every feeding thereafter full strength.
This may be overkill but what I do.
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Last 4 grows ive feed full strength once ppms reach 800/1000. Full strength till harvest.
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I use jacks and I love it. I have a perpetual harvest so I can use the same mix for my veg tent and flower tent so canāt beat that. I add only silica and epson salt. I also use general hydro kool bloom liquid and powder to ripen the last two weeks. I believe that works well for a bloom booster. I am considering giving ruby fulvic and winter frost a go when Iām out of kool bloom. Canāt go wrong with jacks.
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yes they do! Well done Brother 
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Your colas are totally engorged! 
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You would be better off to give the plants a jolt of this early in flower so that P and K are on board the plant for itās use. Running the last two weeks likely wonāt benefit you.
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I use the liquid kool bloom from the start of flowering and then switch to the powder formula which gh labela says to use on the last week or two of flowering to promote trichome production and ripening. This is per gh instructions. Would you still recommend I switch it up?
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So long as youāre providing P and K early in flower thereās no reason to not follow GH grow schedule.
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