Jack's Nutrients Feeding Schedule

About Jack’s Nutrients

Jack’s is a water-soluble powder, and it is what a lot of commercial growers move to once they get tired of paying to ship water. The classic program is three parts — 5-12-26 Part A, calcium nitrate Part B, and Epsom salt — and it produces a complete, fully controllable feed for a fraction of what an equivalent bottled line costs.

The trade-off is that you mix it yourself and you need a scale. If you are running more than a couple of lights, that trade is usually worth it. It also stores forever, which matters when you buy by the pallet.

The feed chart

These are Jack’s own published figures, set out so you can read them on your phone in the grow room instead of pinching around a PDF. Jack’s prints its schedules as a target EC/ppm range per stage plus a per-product dosing reference marked with checkmarks showing which stage(s) each salt is used in — we have laid those checkmarks out as stage columns below so you can read straight across a row. Four schedules are covered: the standard 321 one-gallon program, the 321 and 0-12-26 program scaled for a 100-gallon batch tank (or a 1:100 injector), the A+B Fast Track program, and the single-bottle 15-5-20 Base program.

Jack’s 321 Schedule (1 Gallon)

Jack’s 321 Schedule (1 Gallon) — All amounts per 1 U.S. gallon
Feed	Propagation	Veg	Bud Set	Flower	Late Flower	Flush
Growth stage	Propagation (seedlings, clones, young plants)	Vegetative	Bud Set (start of 12-hour photoperiod; use 10-30-20 for 1 week)	Flower	Late Flower (use 7-15-30 Finish for 1 week)	4-7 Day Flush (clear water)
Target EC (mS/cm)	1.1	2.4	1.9	2.4	2.1	—
Target ppm (500 scale)	550	1200	950	1200	1050	—
Target ppm (700 scale)	770	1680	1330	1680	1470	—
Jack’s 15-6-17 Clone (g/gal)	3.15	—	—	—	—	—
Jack’s 5-12-26 Part A (g/gal)	—	3.79	—	3.79	—	—
Jack’s 15-0-0 Part B (g/gal)	—	2.52	—	2.52	—	—
Jack’s 10-30-20 Bloom (g/gal)	—	—	5.68	—	—	—
Jack’s 7-15-30 Finish (g/gal)	—	—	—	—	5.41	—
Epsom salt (g/gal)	—	0.99	0.99	0.99	0.99	—

Jack’s 321 and 0-12-26 Schedule (100 Gallon)

Jack’s 321 and 0-12-26 Schedule (100 Gallon) — All amounts per 100 U.S. gallons of water, or per gallon of stock concentrate for injectors set at 1:100
Feed	Clone	Veg	Bud Set	Flower	Late Flower	Flush
Growth stage	Clone	Vegetative	Bud Set (1-2 weeks)	Flower	Late Flower (1-2 weeks)	Harvest
Target EC (mS/cm)	1.0-1.2	1.8-2.4	1.8-2.1	1.8-2.4	2.2-2.6	—
Target ppm (500 scale)	500-600	900-1200	900-1050	900-1200	1100-1300	—
Jack’s 15-6-17 Clone (g/100 gal)	315.45	—	—	—	—	—
Jack’s 5-12-26 Part A (g/100 gal)	—	378.54	—	378.54	—	—
Jack’s 15-0-0 Part B (g/100 gal)	—	252.36	—	252.36	252.36	—
Jack’s 10-30-20 Bloom (g/100 gal)	—	—	567.81	—	—	—
Jack’s 0-12-26 Part A (g/100 gal)	—	—	—	—	378.54	—
Epsom salt (g/100 gal)	—	98.94	98.94	98.94	98.94	—

Jack’s A+B Fast Track Schedule (1 Gallon)

Jack’s A+B Fast Track Schedule (1 Gallon) — All amounts per 1 U.S. gallon
Feed	Clone	Veg	Flower
Growth stage	Clone	Veg	Flower
Target EC (mS/cm)	1.1	2.2	2.8
Target ppm (500 scale)	550	1100	1400
Jack’s 15-6-17 Clone (g/gal)	3.15	—	—
Jack’s 5-12-26 Part A (g/gal)	—	3.80	5.68
Jack’s 15-0-0 Part B (g/gal)	—	2.50	2.50

The source PDF lists Jack’s 5-12-26 Part A as two separate dose lines (50 ppm N / 3.80 g in Veg, 75 ppm N / 5.68 g in Flower). Merged into one row here since it is the same product at two rates.

Jack’s 15-5-20 Base Schedule (1 Gallon)

Jack’s 15-5-20 Base Schedule (1 Gallon) — All amounts per 1 U.S. gallon
Feed	Propagation	Veg	Bud Set	Flower	Late Flower	Flush
Growth stage	Propagation (seedlings, clones, young plants)	Vegetative	Bud Set (start of 12-hour photoperiod; use 10-30-20 for 1 week)	Flower	Late Flower (use 7-15-30 Finish for 1 week)	4-7 Day Flush (clear water)
Target EC (mS/cm)	1.1	2.1	1.9	2.1	2.1	—
Target ppm (500 scale)	550	1050	950	1050	1050	—
Target ppm (700 scale)	770	1470	1330	1470	1470	—
Jack’s 15-6-17 Clone (g/gal)	3.15	—	—	—	—	—
Jack’s 15-5-20 (g/gal)	—	5.05	—	5.05	—	—
Jack’s 10-30-20 Bloom (g/gal)	—	—	5.68	—	—	—
Jack’s 7-15-30 Finish (g/gal)	—	—	—	—	5.41	—
Epsom salt (g/gal)	—	0.99	0.99	0.99	0.99	—

A dash means Jack’s own chart prints no target for that stage — the Flush/Harvest column is plain water, no nutrients added.

Each product row shows the same per-gallon (or per-100-gallon) dose in every stage column Jack’s checks it for; a blank cell means that product is not used in that stage. The source PDFs also list Dry Oz. equivalents throughout, and Lbs. for the 100-gallon program, for growers who prefer those units over grams.

Figures as published by Jack’s Nutrients / JR Peters (documents 3230c0_15ef9a140f114133bb1be94c8e6ad079, 3230c0_bba5b5304abf454ea4acc6ee042abbd5, 3230c0_2c6597e4cf9349dbafb03283e8db4a2d and 3230c0_f40abdbc1fe64a29bf97e9f53cb2bb8f). Feeding charts are recommendations only. Adjustments may be needed based on environmental conditions, your grow structure, and any additional products you run. Actual results vary.

Download the original charts

All four are Jack’s own files, hosted here so the links do not rot:

What we stock

The 25 lb bags and the smaller sizes, plus pallet pricing for facilities.

Shop Jack's Nutrients

Everything on this schedule, stocked at Milford and Webster.

View all 24 Jack's Nutrients products →