Heavy 16 and Bloom
Heavy 16 on the left, Bloom on the right, matched on the job each bottle does. Your Veg and Bud base and Prime stay. Here’s where Bloom’s stage bottles sit in.
Last checked 5 November 2026 · Public information only
This Fit Report is a summary of publicly available information about Heavy 16 and its products, taken from their own website, labels and published material as of 5 November 2026. We’ve linked each source so you can check it yourself. Rates are as printed on each company’s own pages; we don’t show prices. It isn’t affiliated with, endorsed by or approved by Heavy 16, and product names belong to their owners. Products, rates and claims change, so please confirm current details with the manufacturer before making any decision. Spotted something out of date? Email nathan@bloomyellowbottles.com and we’ll correct it.
Fewer bottles on their side, one per stage on ours.
Heavy 16’s About page talks about more science, fewer bottles, and Prime puts kelp, humic and fulvic, carbs, potassium silicate and trace minerals in one. Bloom goes the other way, with a bottle timed to each stage. Their list has no veg-shape, flip, bulking or late flower additive, so that’s where Bloom fits cleanest.
- Stays as is: Veg A & B, Bud A & B and their nutrient calculator.
- Both have one: a tonic, a root additive, a bloom PK, a foliar and a finisher. Run one, or test them side by side.
- Not on their list: Pre, Ultra, Phat, Ooze, a separate cal-mag or silica, fish, and pest control.
Their line, Bloom’s fit at a glance
Matched on job, not NPK. Heavy 16 doses in mL per gallon through its calculator; Bloom prints ml per litre on a weekly feed chart. Tap a tag to filter.
Keep your base. Bloom’s additives sit on top of it.
Prime puts these inputs in one bottle; Bloom sells them one job at a time. Pick one, or plan the stack.
Both are root additives. Heavy Roots also lists drip cleaning. Pick one.
Both are P and K. Fire runs the whole bloom; Bloom PK is an as-needed bottle at peak bloom.
All three are foliar sprays in the same window. Plan the spray days before running both.
Both sit at the very end. Plan the last fortnight before running both.
One-stage additives that go on top of Veg, Bud and Prime.
Stage-timed flower additives on top of Bud A & B and Fire.
Their FAQ says calcium comes through Veg, Bud and Foliar. Add it only if your water calls for it (our read).
Prime lists potassium silicate inside it. A separate bottle sets silica on its own (our read).
Tuna and kelp, tapering at the flush.
Insecticide and miticide, OMRI Listed per its product page.
Put it side by side
Where both ranges have a product for the same job, the fair answer is a test in your own room. Here’s what to watch and how to keep it fair.
Keeping it fair
- Same plants. Clones off the same mother, same cultivar, same age.
- Same room. Same light, climate, media, pot size and watering.
- Same base. Keep the base feed and EC the same on both sides.
- One change. Change only the product being tested, and write down what you see each week.
Why each one fits
What the Bloom product does, the research behind that kind of input, and where it sits in a program that already runs.
Pre in veg, Ultra at the flip
What it does. Pre runs mid veg (weeks 2–3) and Ultra flower weeks 1–2, both at 1 ml/L weekly. These are timing tools, so there’s no study cited for them here.
How it stacks. Their calculator repeats Veg week 2 for longer veg. Pre and Ultra slot into those same weeks without changing the base mL/gal (our read: check runoff when you add anything).
Phat, then Ooze into the flush
What it does. Phat at 2.5 ml/L weekly in flower weeks 3 and 4. Ooze at 2.5 ml/L weekly from week 5 right through the final flush, with Final at 1 ml/L weekly for the last two weeks alongside it. Ooze lists plant extracts, fulvic acid, vitamins and amino acids.
How it stacks. Bud A & B and Fire carry the bloom base and P and K. Phat and Ooze sit on top by stage. Heavy Finish is their flush, so plan the last fortnight before running Final with it (our read).
Silica on its own
What it does. Potassium silicate at 0.33 ml/L weekly, added first, veg through early flower, tapering in late bloom.
An editorial on silicon research says it helps plants with some stresses, but there’s no conclusive evidence on how, and most work is on grasses.
Deshmukh, Ma and Belanger (2017), Frontiers in Plant Science (editorial)
How it stacks. Prime’s page says growers can vary its rate by environment and phase. A separate silica holds steady while Prime moves (our read).
Tuna and kelp
What it does. Seafuel is tuna and kelp at 1 ml/L weekly, clone through late flower, tapering at the flush.
Work on protein hydrolysates, the group fish inputs sit in, links them to nutrient uptake and stress responses. It’s a newer field and doesn’t test this bottle.
How it stacks. Prime already brings kelp. Count that before adding Seafuel’s kelp on top (our read).
Where the programs complement each other
Phat and Ooze on top of Bud and Fire
Their bloom side is the Bud base plus Fire’s P and K ramp, with no bulking or late flower bottle on the list. Phat runs weeks 3–4 and Ooze week 5 through the flush, both at 2.5 ml/L weekly.
Pre and Ultra in the weeks they already run
Their calculator repeats Veg week 2 for longer veg and starts Fire late in veg. Pre and Ultra are one-stage bottles for exactly those weeks, at 1 ml/L weekly.
OrganiShield for pest control
Their foliar page says Heavy Foliar can be mixed with pesticides, but their range doesn’t list a pest product. OrganiShield is an insecticide and miticide; check both labels before any tank mix (our read).
Where each bottle sits in the cycle
Heavy 16’s timing in grey, Bloom’s in yellow, across shared stages of the grow.
| Stage | Root | Veg | Flip | 3–4 | 5+ | Last 2 | Flush |
|---|---|---|---|---|---|---|---|
| Heavy 16, per their pages | |||||||
| Heavy Veg A & B | |||||||
| Heavy Bud A & B | |||||||
| Heavy Prime | |||||||
| Heavy Roots (Heavy 16) | |||||||
| Heavy Fire | |||||||
| Heavy Foliar (every 3 days) | |||||||
| Heavy Finish | |||||||
| Bloom, per Bloom’s weekly feed charts | |||||||
| Roots | |||||||
| Pre | |||||||
| Ultra | |||||||
| Phat (weeks 3 and 4) | |||||||
| Ooze (wk 5 to flush) | |||||||
| Final (with Ooze) | |||||||
| Seafuel | |||||||
| Seaweed · Humate · Sea Minerals | |||||||
| SWTNR | |||||||
| Cal-Mag | |||||||
| Groigen (foliar, as needed) | |||||||
| Florigen (foliar, as needed) | |||||||
| PK (as needed) | |||||||
| Silica | |||||||
Timing comes from each Heavy 16 product page and the nutrient calculator page. Their week-by-week rates sit in the calculator output, so where Bud A & B stops and Finish starts is our read. Fire starts in the last 1–2 weeks of veg, so veg is pale. Heavy Roots runs to the last week before harvest. Bloom’s bars follow its weekly feed charts; pale Bloom bars are as-needed bottles or tapers.
Already covered
- Base feed. Veg A & B then Bud A & B.
- Whole-cycle tonic. Prime lists kelp, humic and fulvic, carbs, silicate and trace minerals.
- Roots. Heavy Roots from clones to the last week.
- Bloom P and K. Fire ramps through bloom.
- Foliar and finish. Foliar to flower week 4, Finish for the final flush.
Stays exactly as is
- Veg A & B and Bud A & B. Your base. Bloom’s additives sit on top.
- Prime’s pH role. Their FAQ says Prime regulates pH. Bloom has no pH product.
- Heavy Finish. Bloom has no flush or clearing solution.
- Prime, Roots, Fire, Foliar. If they’re working in your room, keep them, or test Bloom’s next to them.
Background, science and sources
Who Heavy 16 are
Heavy 16 is a California nutrient brand started by Bryce Patterson, who studied ag and horticulture science at Cal Poly San Luis Obispo. It began as custom batches for local growers before going nationwide. The listed address is Signal Hill, CA, and the site says the brand is powered by Hydrofarm.
The range is a two-part Veg and Bud base plus five additives: Prime, Roots, Fire, Foliar and Finish. Rates come from an online nutrient calculator in mL per gallon. It’s sold through retail stores, with a retailer finder and a retailer sign-up.
What each company brings
Heavy 16: A two-part Veg and Bud base, an all-cycle tonic (Prime), a root additive, a P/K bloom booster, a calcium and magnesium foliar spray and a fulvic finisher, with an online nutrient calculator.
Bloom: one additive for each stage of the crop, seaweed, humic and sea mineral inputs, foliar sprays, and weekly feed charts for soil, coco and hydro. Rates and timing are on every product page.
Cropping Solutions, the other brand under Agricultural Organics, isn’t part of this report.
Dose basis: how each side counts
Heavy 16 doses in mL per gallon rather than ppm, and its FAQ says some ingredients don’t show on EC meters. Most rates sit in the calculator, not on product pages. The one rate printed on a product page is Heavy Roots at 1 mL per gallon of reservoir, about 0.26 ml/L.
Bloom prints ml per litre on a weekly feed chart. So the same number on each side isn’t the same weekly amount, and the analyses differ too.
Mix calculator
Rates as printed on each company’s page (1 US gallon is 3.785 L). Bloom’s rates are per litre of nutrient solution, dosed weekly per its feed charts. Pick a product and your tank size.
Humic and fulvic acidsWell supported
Canellas and colleagues (2015) review humic and fulvic substances in horticulture and link them to more lateral root growth and to root changes tied to nutrient uptake.
Why it matters here: Prime lists humic and fulvic acids and Finish is a fulvic fraction. Bloom’s Humate is humic acid too, so plan one humic source per feed (our read). The review doesn’t test either brand.
Potassium in bloom and under stressWell supported
Hasanuzzaman and colleagues (2018) review potassium’s roles in photosynthesis, stomata and carbohydrate metabolism, and in tolerance to drought, salt and heat.
Why it matters here: Fire and Bloom PK are both P and K, and Prime lists several potassium forms. Add up potassium across the stack before running both (our read).
Sources, all viewed 5 November 2026
Heavy 16: Home · About Us · Products · Heavy Veg A & B · Heavy Bud A & B · Heavy Prime · Heavy Roots · Heavy Fire · Heavy Foliar · Heavy Finish · Nutrient calculator · Knowledge and FAQ · Foliar directions
Bloom: Roots · Pre · Ultra · Phat · Ooze · Final · Seafuel · Seaweed · SWTNR · Humate · Cal-Mag · Groigen · Florigen · Sea Minerals · PK · Euro · Grow · Flower · Silica · OrganiShield
Last checked 5 November 2026. Public information only. Not affiliated with, endorsed by or approved by Heavy 16; product names belong to their owners. Please confirm current details with the manufacturer. Corrections: nathan@bloomyellowbottles.com. All Fit Reports