Jack Bloom Booster - What Ratio?


I currently use Jacks 321 + Silica. Formula from this forum. My girl has recently begun to flower. Plant doing well.

I know I can use Jacks 321 all the way through to the end. But, I am considering Jacks Bloom Booster.

Question — Do you recommend Bloom Booster? If so, what formula do you use? Do you use it in place of or “with” the Jacks 321? How long do I use the booster?

  • Seed: Do-si-dos, Photo, from ILGM
  • Vessel: Coco + Perlite, 5 gal fabric pot
  • Nutrition: Jacks 321 + Silica
  • PH of Water: 62 (I do not test runoff or ppm)
  • Environment: Outdoor
  • Location: Southern US, hot and humid
  • Temps: Upper 80s
  • Humidity; It’s the South

I use booster in place of 321 follow directions listed for usage

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You can experiment from there as you might be able to go a good bit hotter growing in coco

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Here’s how I handle Jacks. I don’t use their Bloom product, but do use a monopotassium phosphorus (MKP) based fertilizer during the transition from veg to flower. Feeding ratios adapted from the honorable @Nicky

Jack’s 321 standard mix & used for veg= 3.6/2.4/1.2

Booster mix= Jacks Part A/ Cal nitrate (Part B) / Epsom salts / MKP


Flower mix= 3.8/2.2/1.2.

If calcium issues try 3.7/2.5/1.1


The schedule is online


You can adjust your feed. @Graysin’s recipe is wonderful. I also incorporate Fox Farm Dry Boosters (Open Sesame, Beastie Bloomz, and Cha Ching) at about ½ strength. My PPM’S, with Silica Blast added first, fall at almost exactly 1,150 and pH falls just around 6.35 (starts at 7.7 from tap). With Jack’s 321, if you can get the ratios right, there isn’t a whole lot of need for boosters. Mad trich production. Steady, healthy growth. I’ve seen some even go double strength and still not burn up a plant. Sorry if none of this answered your question.


Hello and thanks for taking the time to provide the info.

I “think” that since I am a one plant at a time grower, I’ll stick with just jacks 321 through harvest.

As i get more into this hobby, I may get more detailed with my fertilizer.

Funny when I think about it….I started this hobby by thinking I’d just plant a seed and see what it does. Since then I’ve learned about soil (and coco) and nutrients and PH, photo vs auto and so much more. My head is spinning trying to add in more when I’m just a single plant grower….for now. (Not in a friendly state)

Appreciate the guidance. I’ll go slow for now.


That’s how it starts lol. It is a very fun, interesting and super relaxing when you really start getting into it. I’m not in a friendly state either.


@Graysin what week do you start this booster from flip or start of week 2 thru week 4?


I start right when I move them to 12/12 and do it for 2-3 weeks, depending on how long it takes them to stop stretching and show me nice hedgehogs.