Jacks 321 elemental breakdown ppm.
I’ve found my coco needs more Ca in veg.
MKP is potent stuff. A lil goes a long way.
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Never used Jack’s, so I can’t do a direct comparison, but regarding value/cost, I’m just gonna’ leave this right here…
tl;dr: I got almost 3 pounds and spent $6.16 (not including Botanicare Cal-Mag)
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Ive never used maxibloom, so i cant really give a solid opinion. I do know of one person who switched to Jacks from GH Maxibloom, and they are having good luck. I also know some who tried Jacks, but liked their other stuff better… ive only used Fox Farms trio and Jacks.
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I do the same… except I’ve been using the Urban Farms Vegetable Fertilizer in veg. Once that gallon is gone I’ll switch to the Jack’s 20-20-20 which I already have on hand.
I usually add 1TBSP per 5 gallons, but have used as much as 1tsp per gallon (1TBSP = 3 tsp). Besides pHdown, the only other thing I add is the same amount of Cal-Mag. I picked up a gallon of Cal-Mag-Iron from Humboldt’s Secret since it was discounted during the last Amazon Deal Days. My plants seem happier now than when I fed them a different Cal-Mag product.
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I have AN micro/grow/bloom to use up but when it’s gone I plan on trying Jack’s 321
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If you’re trying to amend the 321 schedule, I haven’t found much use for potassium nitrate. However, I think there is value in potassium sulfate. Usually I consider adding MKP at the end, when the plant does not need more nitrogen.
Usually what I’m trying to do is just tweak 321 using various other amendments. From experimentation, the “safe” rule of thumb is not to exceed half a gram of “other” amendments. You can also do a full swap in some cases. Some example formulas I have been testing are:
(Veg adjusted)
3g Jacks (Southern Ag 5-11-26)
2g Calcium Nitrate
1g Magnesium Nitrate
(option 0.25 Fertilome 9-58-8)
(Bloom adjusted, first 1-2 weeks)
3g Jacks (Southern Ag 5-11-26)
2g Calcium Nitrate
1g Epsom
0.25-0.5g Fertilome 9-58-8
(Finish adjusted, last 1-2 weeks)
3g Jacks (Southern Ag 5-11-26)
2g Calcium Nitrate
1g Epsom
0.25-0.5g MKP (or possibly split 0.5g 50/50 with potassium sulfate)
A more exotic bloom formulation I’m considering this time is:
3g Jacks (Southern Ag 5-11-26)
2g Fertilome 9-58-8
1g Epsom
0.5g Calcium Nitrate
But it definitely could only be useful for a week or so, due to low Ca. This recipe comes very close to Jacks 10-30-20, but still has some Calcium.
Edit: I should note that these are just the ratios I use, and add water until I hit the specific EC target I’m looking for.
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Have you ever tried matching their EC schedule? I’m quite surprised to see their “bud set” target EC all the way up at 1.9 already. I have always figured that they must be vegging for a very long time, because I’m usually starting plants in flower at like 1.4-1.5 after 3-4 weeks of veg. Also their veg shows 2.4 EC, which can only mean that is the target for fairly mature plants.
It has made me question if their nutrient ratios need to be adjusted for shorter veg times as well. I think most people don’t veg long enough to hit 2.4 in veg.
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That’s what I was looking for. Sorry old and stoned again. Thanks!
Blessings…
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The only thing I don’t like is they put in grams/pounds why not give the measurements in ml like the little spoon/cup they give you with the Jack’s Classic? Got me a bit confused
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I feel like such a dummy 
Just checked the conversion and they are the same I’ll go sit in the corner now…
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Thanks for the link-
Great thread…
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You’re very welcome,and I’m glad you liked it! It just goes to show that you don’t have to spend a lot to get a lot. I used to use House & Garden’s full line of nutes, which costs more for one run that I now pay for years of grows with Greenleaf Nutrients. It might be comparably priced with Jack’s, but I have no reason to change.
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As ALWAYS, Wisdom from On High!!! Keeping all this in mind for the Summer, Thanks. SS/BW…mister 
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I 'preciate ya, got it Bookmarked for future reference, BIG THANKS, Bro!!! SS/BW…mister
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I have only run the Jack’s with Autos, and we keep it simple running 0.3 seedlings for 2 weeks, 1.0-1.4 for the rest of the cycle.
Some heavy feeders may be able to handle the 2.4, but I generally underfeed rather than overfeed. I am growing some C99 right now at home and they need double the nute strength of everything else. It would probably love the 2.4.
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What is this fertilome stuff?
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Im part of jacks camp.
I run 2.4g/1.6g/0.8g per gal. This gets to 1.4EC.
I do their finish for last 2 weeks. At a 5:1 ratio to epsom salt to get to 0.8EC. This is around 1.5g and .3g per gal
Im going to try the bloom mix first two weeks if flowering
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Jacks is great stuff. GLN basically makes their version of jacks for slightly cheaper. I basically make my own nutrients from acid digestions, but I am doing some side by side test of the GLN (same as jacks) to see if there is a noticeable difference (due to cost). In veg I run a 3-1-2, and achieve that by using 2.5mL/Gal pro-teKt, 3.00g/Gal Part A (5-12-26), 3.00g/Gal epsom salt, 1.00mL/Gal Kelp & Fish (1-3-2), and 6.00 g/Gal Cal-Nit. Gives me a ppm of 320N, 45P, & 196K. When you correct the P & K you end up with 103P & 236K, or an NPK of 320-103-236 (you move the decimal, NOT divide by the smallest); therefor ending up with a ratio of 3.2-1.0-2.3. Works out great and also gives a good PPM of Ca + Mg (with a 3:1 for Ca:Mg)
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It’s just MAP and MKP balanced for N/K. Makes a good P supplement because it doesn’t throw off the ratios of the other macros.
There are other companies that supply a 9-58-8 formula. Fertilome is the the brand they sell at my local garden store.
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