I was wanting to switch to Jack’s for my vegging plants because I’m having trouble keeping young plants happy as they veg for 60 days. The organic amendments I use are great in bigger pots but not as good in Solo cups. I grow in Roots Organic soil in 5 gallon pots and I wanted to try something simple and effective like Jack’s.
Which NPK number fertilizer they make is the one people use the 321 system with? Is it the 5-12-26 or the bloom at 20-30-20 or both? I’m thinking I need both but I really don’t know. Thanks for any help you can offer.
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I use the pro 20-20-20 at 1\2 tsp. per gallon tap water every watering.
Sunshine mix#4 and absolutely nothing else.
Comes out around 3-3-3 with zero problems and healthy plants till harvest.
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321 is
3.8g/g 5-12-26
2.5g/g Cal nit
1g/g Epsom
Mix cal nit LAST.
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Thanks for the help! I’d love to have just a one part fertilizer. Does that have enough micronutrients to avoid adding epsom salt for extra Magnesium? I seem to get Magnesium deficiencies in veg a lot and just use .8 grams of Epsom salt to keep them plants happy. Thanks again for the response.
Edit: Sorry that was in response to Arb. Forgot to hit reply.
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Greenleaf Mega crop makes a good one part. 
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I’ve seen a several grows that run Mega Crop and do well with it. Does that have everything you need for veg and flower or do you need micro nutes like Calcium and Magnesium? A simple one part would be so great as I’m disabled and mixing nutes is hard sometimes. Thanks for the suggestion.
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It does have everything you need. If using LED’s you might need a cal mag supplement from time to time. 
a lot of peeps use this one its hidden gem and cheap
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Thanks, yeah they’re going to be under 700 watt Spider Farmer LEDs and I frequently see Magnesium deficiencies if I’m not adding epsom salt every watering. I really appreciate the help, I’ve used a bunch of stuff over the years but mainly the GH trio.
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Give it go man, just start low and baby it up. tag me if you need some help brother. 
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It has everything the plants need don’t add anything to the pro 20-20-20.
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For the 321 you use 5-12-26 with the 15-0-0
There’s a thread on here about this also.
The 20-20-20 does great also and is easy.
If you wanted an easy micro supplement, this one’s excellent according to everyone who uses it:
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why do LEDs affect cal/mag needs? That trips me out
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Others can answer this better than me. It has something to do with temperature and LED not putting off as much heat as HPS
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If you’re converting to jacks 321 kootmed.com has some great feed charts with some tested additives. It was pretty handy when I started using it a few years ago.
https://kootmed.com/.downloads/FEED/JACKS-3-2-1.pdf
Green gene also has an awesome video https://youtu.be/6rfHEUwhXsM
I’ve used it for years under full spectrum led’s and I find that some strains want more magnesium others don’t. It’s more about listening to your plant than anything and that just comes with experience and making mistakes. I found I made less mistakes when I started with a good guide and then figured it out from there.
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I gotta research more but I like the theory put forward by Tony from Dutch Passion, that chlorophyll is formed using magnesium and that plants struggle to make enough to photosynthesize effectively under high-intensity LEDs especially without the IR benefits of leaf surface temps being raised and thus transpiration. Raising temps and supplementing magnesium realigns the nutritional needs back to health. It makes sense to me.
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Thanks for the guide, it should be a huge help if I still go with Jack’s. I have to say the simplicity and ease of use with the Megacrop one part sounds really good to me. My hands shake pretty bad some days from nerve problems in my lower spine so the less I have to mix and try to be really precise the better.
I like Dr Earth dry amendments for once they get to the final pot, the ease of use and cost is hard to beat. So many of my strains would start getting the interveinal chlorosis that you see as the first sign of a Magnesium deficiency that I just started giving them all the same Epsom salt with watering. It pretty much eliminated it and the rare cultivar that doesn’t like it usually starts to show a Calcium deficiency from the extra Magnesium. Thanks for the guide again, having a starting point like you said is a big help.
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I do find my plants like it above 80 with the led lighting. When they run colder I start having much more issues with feed strength and watering. My leaf surface temperature is only about 2.5-3 degrees above ambient due to the hight I run my light and the lack of IR.
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Sounds like you’ve got your mag issues handled, I also find my plants are happy under LEDs at or above 80 degrees. If you’re limited in your motion and stamina, maybe something like Osmocote would be a good answer for you, @OldUncleBen is the guy to talk to about that, and he’s definitely familiar with it vs Peters or Jack’s commercial dry nutes.
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I also run jacks 321 and have not looked back ever since.
Great product.
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