Jack's 321 discrepancy

Hi everyone,

I’m setting up my next grow to use jacks 321 nutes. I ordered a 7lb kit because I couldn’t find the 2lb A&B parts…

Anyways… I have 2 schedules I downloaded but noticed today that they don’t show the same values. The weights are different. Anyone else run into this?

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This is what I ordered except mine was the 7lb kit. I see these bags appear different than the 25lb bags on Amazon. Are these old? Is that why there’s 2 different schedules?


Typo in the advertisement I think… the labels are right cal N is 15 0 0 and micro is the 5 12 26 and epsom is Epsom


I bought part A and part B off of Amazon about 2 months ago. I’ve also bought straight from Jacks website.
Like @fano_man said, might be mis print.
Use the schedule with Epson salt @ 1.00 grams.
Good luck! :v::+1:t2::sunglasses:


It’s 3.6 part a then 1.2 Epsom and 2.4 part b per gallon of water should come out to around 900 ppms never had a problem with the jacks so far love it easy to use.


Neither of those are grow schedules. Says right there: these are for adjustments to your schedule.

3.6, 2.4, 1.2 per gallon puts you at around 1,000 ppm

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Thanks for the clarification. I figured as much but didn’t know which was correct

@Myfriendis410 im not sure what you mean. Im thinking those are definitely schedules but they can be tweaked if necessary. I actually can’t find the word adjustment lol, but I could be wrong

This is my 2nd grow, 1st with jack’s so if I sound stupid I apologize

I planned on using those measurements/weights as indicated throughout the growing process. I have no base other than my soil. I was going to wait until happy frog was under 1000ppm at runoff or in slurry before I begin with jack’s

I have the grow schedule for Jack’s (no idea where I found it) and it is a different callout than those. Read what it says on both of them. That’s why I said they’re for tweaking your mix.

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Naw those are just ratios…schedules are more of a when

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Use 3.6 grams Part A, 2.4 grams Part B and 1.2 grams Epsom per gallon. THAT’s Jack’s 3-2-1 and is what most of us are doing with it. Really; you’re just making it hard on yourself lol.

Mix Part A and let it dissolve thoroughly (it may take 1/2 hour) then mix Part B and Epsom. I do those two together as the amounts for a 5 gallon Homer is 18 grams A, 12 grams B and 6 grams Epsom.

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Think you mistyped. Part B is the cal nitrate. You don’t want to mix the cal nitrate with the magnesium sulfate. Those are the two that react and bond to each other.


Right from the Jack’s website:

I do cheat and dump Epsom in after weighing Part B then in it goes together. Mixes fine. The only issues I had mixing were with silica but ironed that out.

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I got 950ppm… good call

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can you post your schedule?

This isn’t the Jack’s schedule but the one I’m using (along with others here)

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I was looking at the check marks in the columns under each grow cycle. So for flowering I add A and B and epson each time I water through flower stage except at the very end I would use jack’s finish and epsom. For Bud set, I would just use jacks 10 30 20 bloom and epson salt

That’s how I thought it worked

Jack’s 3-2-1 ratio all the way through grows gucci plants. You don’t need all of the other supplements. If you want, you can modify the schedule the first 3 weeks of flower and do a 2-2-2-1.2: Part A, Part B, Epsom and MKP (monopotassium phosphate) as a bloom boost then return to 3-2-1 formula.

You’re making it too hard on yourself by over-thinking it. I also add silica about the time I flip when I SCROG and discontinue about week 5 or 6.

Print that schedule and read the whole thing, then follow it.

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Ok, thanks. I’ll print that out have a hard look. But you’re saying I only need to use the 321 and not all the other stuff except for silica and MKP (how much). Do you use recharge or molasses?

To clarify your modification that’s 2.2g A 2g B 1.2g epsom

Thanks for all your help my friend

And silica if you want it. Be sure to mix silica first.

Just to be crystal clear: 3.6 grams of Part A is 3 times the Epsom. Part B is 2 times the Epsom. You could mix 3 grams of Part A, 2 grams of Part B and 1 gram of Epsom. The numbers I quoted though give you a decent solution concentration.

If you want to geek out and learn about this stuff, watch this video:

Professor of Plant Science at Utah State and been growing hemp (cannabis) for 30 years: he knows a thing or two.

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