# Building a cannabis feed by stage: ppm targets per element and how to hit them

> A good mineral cannabis feed runs roughly N 150–200, P 30–60, K 175–250, Ca 150–200, Mg 40–70 and S 60–120 mg/L in veg and flower, plus Fe 1.5–3 and small amounts of Mn, Zn, B, Cu and Mo, at an EC of about 1.2–1.8 mS/cm in veg and 1.6–2.2 in flower. Cannabis research shows no benefit from pushing P or overall strength higher. This article gives the targets, the evidence behind each, and two worked RO-water recipes with a sources table.

- Canonical: https://genetixbay.com/knowledge/nutrients/feed-by-stage.html
- Category: Nutrients · Level: Advanced
- Evidence: Supported · Status: Draft: awaiting expert review (some figures are being checked)
- Stage: Seedling, Veg, Transition, Flower, Ripening · Systems: DWC, RDWC, NFT, Ebb and flow, Drip, Coco, Rockwool, Aeroponics
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Questions and answers

**How many ppm of each nutrient does cannabis need in veg and flower?** In veg, a mineral cannabis feed runs about N 150-200, P 30-50, K 175-240, Ca 150-200, Mg 35-70 and S 60-100 ppm (mg/L). In mid flower it shifts to roughly N 140-190, P 40-60, K 200-280, Ca 150-200, Mg 40-70 and S 60-120 ppm, plus iron at 1.5-3 ppm and traces of manganese, zinc, boron, copper and molybdenum.

**What EC should I run for cannabis in veg and flower?** Cannabis in coco or hydro usually runs about 1.2-1.8 mS/cm in veg and 1.6-2.2 mS/cm through transition and mid flower, easing to 1.2-1.8 mS/cm late in flower. This EC ladder is grower practice. Research in deep-flow hydro found that doubling strength from 2 to 4 mS/cm gave no yield or quality benefit, so higher EC is not better.

**How do I make my own cannabis nutrients from salts?** To make cannabis nutrients from salts, get a water analysis, then weigh single salts such as [calcium nitrate](https://genetixbay.com/knowledge/glossary/calcium-nitrate.md), [potassium nitrate](https://genetixbay.com/knowledge/glossary/potassium-nitrate.md), MKP, [magnesium sulfate](https://genetixbay.com/knowledge/glossary/magnesium-sulfate.md) and [potassium sulfate](https://genetixbay.com/knowledge/glossary/potassium-sulfate.md), plus iron DTPA and micronutrient salts. Keep calcium nitrate and iron in an A stock and everything else in B. Add A, stir, add B, stir, then adjust pH and check EC.

**What is a good N-P-K ratio for flowering cannabis?** Rather than a fixed N-P-K ratio, flowering cannabis does well on about 140-190 mg/L nitrogen, 40-60 mg/L phosphorus and 200-280 mg/L potassium in mid flower. Controlled trials found a flower nitrogen optimum near 194 mg/L, a phosphorus optimum near 59 mg/L in DWC, and no yield gain above about 60 mg/L phosphorus, so heavy high-P bloom ratios add nothing.

**Do I need to change nutrients between veg and flower?** Cannabis needs only modest feed changes between veg and flower, not a switch to a high-phosphorus, low-nitrogen bloom formula. EC rises from about 1.2-1.8 to 1.6-2.2 mS/cm, and potassium and phosphorus increase slightly, but nitrogen should stay near 160-200 mg/L through the stretch. Dropping nitrogen at the flip starves the stretch; taper it only in the final weeks.

**What EC for seedlings and clones?** Cannabis seedlings and clones are usually fed at about 0.6-1.0 mS/cm, a grower practice range. At that strength the solution carries roughly 50-100 mg/L nitrogen, 15-30 mg/L phosphorus, 60-120 mg/L potassium, 80-120 mg/L calcium and 25-40 mg/L magnesium. Measure total solution EC including the water, and raise strength toward the veg range of 1.2-1.8 mS/cm as plants establish.

**Short answer.** A solid mineral feed for cannabis in coco or hydro runs roughly **N 150–200, P 30–60, K 175–250, Ca 150–200, Mg 40–70, S 60–120 mg/L**, plus Fe 1.5–3 mg/L and traces of Mn, Zn, B, Cu and Mo. Run it at about **1.2–1.8 mS/cm in veg and 1.6–2.2 mS/cm in flower**. Cannabis trials show no benefit from pushing P above about 60 mg/L or from doubling overall strength [4][5][6]. Below: the targets, the evidence, and two worked recipes for RO water.

## Targets by stage

All values mg/L (= ppm by mass of the element) in the solution going to the roots, including what your water supplies. EC values are total solution EC at 25 °C.

| Element | Seedling / clone | Veg | Transition (flower wk 1–3) | Mid flower (wk 4–7) | Late flower / ripen | Evidence |
|---|---|---|---|---|---|---|
| EC (mS/cm) | 0.6–1.0 | 1.2–1.8 | 1.6–2.2 | 1.6–2.2 | 1.2–1.8 | *Grower practice*; 4 vs 2 mS/cm gave no gain [6] |
| N | 50–100 | 150–200 | 160–200 | 140–190 | 100–150, tapering towards 0 at the finish (see note) | Veg optimum ~160 [1]; flower optimum ~194 [2]; taper is *Grower practice* |
| NH₄ share of N | ≤10% | ≤10–20% | ≤10–20% | ≤10–20% | ≤10% | >30% harmful [8] |
| P | 15–30 | 30–50 | 40–60 | 40–60 | 30–50 | No gain above ~25–60 [4][5][6]; optimum ~59 in DWC [2] |
| K | 60–120 | 175–240 | 180–250 | 200–280 | 180–250 | Veg 175–240 [3]; no flower response 60–340 [2] |
| Ca | 80–120 | 150–200 | 150–200 | 150–200 | 130–180 | Standard solutions [9][10]; *Supported* |
| Mg | 25–40 | 35–70 | 40–70 | 40–70 | 40–60 | Veg 35–70 [7] |
| S | 30–60 | 60–100 | 60–120 | 60–120 | 60–100 | *Supported* (standard solutions) |
| Fe | 1.0–2.0 | 1.5–3.0 | 1.5–3.0 | 1.5–3.0 | 1.5–2.5 | Greenhouse standards [9] |
| Mn | 0.2–0.5 | 0.3–0.8 | 0.3–0.8 | 0.3–0.8 | 0.3–0.6 | [9] |
| Zn | 0.1–0.3 | 0.1–0.5 | 0.1–0.5 | 0.1–0.5 | 0.1–0.4 | [9] |
| B | 0.2–0.4 | 0.2–0.5 | 0.2–0.5 | 0.2–0.5 | 0.2–0.5 | [9]; toxicity at ~5 mg/L [10] |
| Cu | 0.03–0.05 | 0.03–0.1 | 0.03–0.1 | 0.03–0.1 | 0.03–0.08 | [9] |
| Mo | 0.01–0.05 | 0.01–0.05 | 0.01–0.05 | 0.01–0.05 | 0.01–0.05 | [9] |
| Na, Cl | As low as possible; Na <50, Cl <50–70 | | | | | See [sodium](https://genetixbay.com/knowledge/nutrients/sodium.md) |

Notes:
- Per-stage splits within veg and flower are *grower practice*; the research gives single optima per phase, mostly from one or two cultivars per study.
- Organic liquid feeds need higher N on paper (one coir trial put the flowering optimum at 212–261 mg/L N) because organic N is less available [see [organic vs mineral](https://genetixbay.com/knowledge/nutrients/organic-vs-mineral.md)].
- Soil growers: these are solution numbers; soil supplies and buffers its own nutrients.
- **Feed through to harvest.** The late flower / ripen column is a real feed, not a wind-down. Don't flush before harvest: pre-harvest flushing is a *Myth* that starves the plant while it packs on its final weight, trichomes and resin, so it costs you yield and resin [see [the flush debate](https://genetixbay.com/knowledge/harvest-cure/flush-debate.md)]. The only valid flush is a [root-zone flush](https://genetixbay.com/knowledge/glossary/root-zone-flush.md) to clear salt build-up, at any stage, when runoff EC says you need one (see [runoff testing](https://genetixbay.com/knowledge/ph-ec/runoff-testing.md)).
- **N and potency are a trade-off.** Lower N in flower can raise cannabinoid and terpene percentage while lowering total yield; yield rose with N up to ~160 mg/L in one controlled trial (Saloner & Bernstein 2021, Industrial Crops and Products 167:113516, https://doi.org/10.1016/j.indcrop.2021.113516). Pick your late-flower N deliberately within the table range; it isn't a reason to flush (see [nitrogen](https://genetixbay.com/knowledge/nutrients/nitrogen.md)).
- **Taper N, don't flush.** From about 3 weeks out, ramp N down: ~75 % of late-flower N at week −3, ~50 % at −2, ~25 % at −1, 0–20 mg/L in the final days, with P, K, Ca, Mg, S and micros unchanged (*Grower practice*). That needs single salts with an N-free Ca source (see [hydroponic salts](https://genetixbay.com/knowledge/nutrients/hydroponic-salts.md)) or [per-element dosing](https://genetixbay.com/knowledge/glossary/per-element-dosing.md); diluting a 2-part cuts everything.

## Sources table: which salt to use for each element

| Element | Main sources | Secondary sources |
|---|---|---|
| N (nitrate) | Calcium nitrate, potassium nitrate | [Magnesium nitrate](https://genetixbay.com/knowledge/glossary/magnesium-nitrate.md), nitric acid |
| N (ammonium) | Already in calcium nitrate (~1.1% NH₄-N) | MAP, [ammonium nitrate](https://genetixbay.com/knowledge/glossary/ammonium-nitrate.md) (small amounts) |
| P | MKP | MAP, phosphoric acid |
| K | Potassium nitrate, potassium sulfate | MKP, [potassium silicate](https://genetixbay.com/knowledge/glossary/potassium-silicate.md), KOH |
| Ca | Calcium nitrate | [Calcium chloride](https://genetixbay.com/knowledge/glossary/calcium-chloride.md) (small amounts) |
| Mg | Magnesium sulfate | Magnesium nitrate |
| S | Magnesium sulfate, potassium sulfate | Sulfuric acid |
| Fe | Fe-DTPA (hydro, coco), Fe-EDDHA (alkaline) | Fe-EDTA (pH < 6.5) |
| Mn, Zn, Cu | Sulfate salts or EDTA chelates | |
| B | Boric acid | Sodium borate |
| Mo | [Sodium molybdate](https://genetixbay.com/knowledge/glossary/sodium-molybdate.md) | Ammonium molybdate |

Salt percentages are in [hydroponic salts explained](https://genetixbay.com/knowledge/nutrients/hydroponic-salts.md).

## Worked recipe 1: veg, RO water

Per 1,000 L (divide by 10 for 100 L). Assumes RO water with EC < 0.05 mS/cm.

| Salt | g per 1,000 L | Supplies (mg/L) |
|---|---|---|
| Calcium nitrate (15.5% N, 19% Ca) | 840 | N 130, Ca 160 (NH₄-N ≈ 9) |
| Potassium nitrate | 380 | N 53, K 147 |
| MKP | 175 | P 40, K 50 |
| Magnesium sulfate heptahydrate | 500 | Mg 49, S 65 |
| Potassium sulfate (44.9% K) | 50 | K 22, S 9 |
| **Totals** | | **N 183, P 40, K 220, Ca 160, Mg 49, S 74** |

## Worked recipe 2: flower, RO water

| Salt | g per 1,000 L | Supplies (mg/L) |
|---|---|---|
| Calcium nitrate | 790 | N 123, Ca 150 (NH₄-N ≈ 9) |
| Potassium nitrate | 200 | N 28, K 77 |
| MKP | 220 | P 50, K 63 |
| Magnesium sulfate heptahydrate | 560 | Mg 55, S 73 |
| Potassium sulfate | 240 | K 108, S 44 |
| **Totals** | | **N 150, P 50, K 248, Ca 150, Mg 55, S 117** |

## Micronutrients for both

| Salt | g per 1,000 L | Supplies (mg/L) |
|---|---|---|
| Fe-DTPA (11% Fe) | 23 | Fe 2.5 |
| [Manganese sulfate](https://genetixbay.com/knowledge/glossary/manganese-sulfate.md) monohydrate | 1.6 | Mn 0.5 |
| Zinc sulfate heptahydrate | 1.3 | Zn 0.3 |
| Boric acid | 2.3 | B 0.4 |
| Copper sulfate pentahydrate | 0.3 | Cu 0.08 |
| Sodium molybdate dihydrate | 0.1 | Mo 0.04 |

Weigh micros into a 1:1000 stock (for example, 1,000× the per-litre amount in 1 L of water) so you dose millilitres, not milligrams.

**Expected EC.** A rule of thumb for nutrient solutions is EC (mS/cm) ≈ sum of cations in meq/L ÷ 10 [9]. Recipe 1 has about 18 meq/L of cations (Ca 8.0, K 5.6, Mg 4.1, NH₄ 0.7), so expect roughly 1.8 mS/cm; recipe 2 ≈ 1.9 mS/cm. Measure; don't trust the arithmetic alone.

## How to use it

1. **Get a water analysis** and subtract what the water supplies (Ca, Mg, S, Na, Cl, alkalinity). See [water quality](https://genetixbay.com/knowledge/ph-ec/water-quality.md).
2. **Mix A and B stocks separately** (calcium nitrate and iron in A; everything else in B).
3. **Fill the tank, add A, stir, add B, stir, then adjust pH** to 5.6–6.0 (hydro) or 5.8–6.2 (coco).
4. **Check EC** against the target.
5. **Monitor runoff or reservoir** (see [runoff testing](https://genetixbay.com/knowledge/ph-ec/runoff-testing.md)) and adjust strength, not ratios, first.
6. **Tissue test** once per cycle if you can (most recent mature leaf): N 3.3–5.0%, P 0.27–0.48%, K 1.8–2.7%, Ca 1.5–2.9%, Mg 0.30–0.65%, S 0.25–0.36% (NC State floral hemp ranges).

## Common mistakes

- Copying a feed chart's EC without accounting for tap water EC.
- Switching to a high-P, low-N "bloom" feed at the flip and starving the stretch.
- Stacking boosters on a complete base (see [bloom boosters](https://genetixbay.com/knowledge/nutrients/bloom-boosters.md)).
- Assuming more EC means more yield: doubling to 4 mS/cm gave no yield or quality benefit in deep-flow hydro [6].

## Evidence

- N, P, K, Mg optima: *Supported* (controlled cannabis trials, mostly one or two cultivars each [1][2][3][4][5][7]).
- P and overall-strength ceilings: *Established* as "no benefit above" across several independent trials [4][5][6].
- Ca, S and micronutrient targets: *Supported* by general greenhouse standards [9] and solutions used in cannabis research [10]; no cannabis dose-response data for most.
- Per-stage EC ladder: *Grower practice*.

## Sources

1. Saloner A, Bernstein N. 2020. Response of medical cannabis to nitrogen supply under long photoperiod. Frontiers in Plant Science 11:572293. https://doi.org/10.3389/fpls.2020.572293
2. Bevan L, Jones M, Zheng Y. 2021. Optimisation of nitrogen, phosphorus, and potassium for soilless production of Cannabis sativa in the flowering stage. Frontiers in Plant Science 12:764103. https://doi.org/10.3389/fpls.2021.764103
3. Saloner A, Bernstein N. 2022. Effect of potassium (K) supply on cannabinoids, terpenoids and plant function in medical cannabis. Agronomy 12(5):1242. https://doi.org/10.3390/agronomy12051242
4. Shiponi S, Bernstein N. 2021. Frontiers in Plant Science 12:657323. https://doi.org/10.3389/fpls.2021.657323
5. Westmoreland FM, Bugbee B. 2022. Frontiers in Plant Science 13:1015652. https://doi.org/10.3389/fpls.2022.1015652
6. Hershkowitz JA, Westmoreland FM, Bugbee B. 2025. Frontiers in Plant Science 16:1433985. https://doi.org/10.3389/fpls.2025.1433985
7. Morad D, Bernstein N. 2023. Plants 12(14):2676. https://doi.org/10.3390/plants12142676
8. Saloner A, Bernstein N. 2022. Nitrogen source matters. Frontiers in Plant Science 13:830224. https://doi.org/10.3389/fpls.2022.830224
9. Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6
10. Cockson P, et al. 2019. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432