If you've got plants in front of you right now and something looks off — yellowing leaves, purple stems, burnt tips — a cannabis nutrient chart is the fastest diagnostic tool you have. But a chart is only useful if you understand what's behind the numbers. This guide walks you through what every nutrient does, what to feed at each stage, how to read deficiency symptoms, and how to pick a nutrient line that actually delivers. Based on data from over 1,000 grow journals tracked on Grow Guide, 63% of growers use soil and 15% run coco coir — so we've included specific targets for both.
What a Cannabis Nutrient Chart Actually Shows You
A nutrient chart is a stage-by-stage feeding schedule expressed in either EC (electrical conductivity, measured in mS/cm) or PPM (parts per million), broken down by the nutrient brand's product line. Every major brand publishes one — General Hydroponics, Canna, Advanced Nutrients, Fox Farm — but the underlying biology is the same regardless of brand.
Nutrients split into two categories:
- Macronutrients (NPK): Nitrogen (N), Phosphorus (P), Potassium (K) — consumed in large quantities
- Secondary/micronutrients: Calcium (Ca), Magnesium (Mg), Sulfur (S), Iron (Fe), Manganese (Mn), Zinc (Zn), Boron (B), Copper (Cu), Molybdenum (Mo)
The ratio of N:P:K shifts dramatically across the plant's life cycle. Getting that ratio wrong at the wrong stage is the fastest way to stunted growth, lockout, or a subpar harvest. Use the Grow Schedule Planner to map your feed schedule against your actual stage dates.
Cannabis Nutrient Chart by Growth Stage
Reading Your Cannabis Nutrient Chart: Stage-by-Stage Breakdown
Seedling Stage (Days 1–14)
Don't feed seedlings. Seriously. A fresh seedling in quality soil or a properly buffered coco mix has everything it needs for the first 10–14 days. If you're feeding at all, cap EC at 0.4–0.6 and only use a seedling-specific formula. Overfeeding at this stage burns roots before they're established and sets back the entire grow. See our Best Nutrients for Cannabis Seedlings 2026 guide for specific product picks.
Vegetative Stage (Weeks 2–8)
This is the nitrogen window. Cannabis in veg is building leaf mass, stems, and root structure — all of which require high N. Target an NPK ratio around 3-1-2 in early veg, moving toward 2-1-2 in late veg as you build up K for structural support. EC should ramp from 1.2 up to 2.0 as the plant matures. Cal-Mag supplementation at 1–2 ml/L is standard in coco, and smart practice in RO-filtered soil grows too.
Transition and Early Flower (Weeks 1–3 of Flower)
The flip to 12/12 (or the natural shortening of days for autos) triggers a stretch and a significant metabolic shift. Start backing nitrogen down while increasing phosphorus. A ratio of 1-3-2 works well here. This is also when many growers introduce a bloom booster. Don't jump straight to full bloom doses — ramp over 7–10 days to avoid shocking the plant.
Peak Flower (Weeks 4–7 of Flower)
Maximum nutrient demand. Phosphorus drives resin and terpene production; potassium regulates osmotic pressure and bud density. EC can sit at 1.8–2.4 depending on strain and medium. Watch leaf tips carefully — if you're seeing slight clawing, back off 10–15%. Trichromes are forming now, so stability matters. Use the Nutrient Deficiency Identifier if symptoms appear — don't guess at this stage.
Flush / Ripening (Final 7–14 Days)
Whether you flush or don't is still debated, but tapering nutrients in the final week is universally agreed upon. Feed plain pH-adjusted water at EC 0.0–0.6. Leaves will yellow and that's normal — it's the plant consuming stored nutrients. Monitor trichomes daily. When most heads are cloudy with 20–30% amber, you're in the harvest window.
Why pH Is the Real Boss of Your Nutrient Chart
You can have a perfect nutrient solution and still see deficiency symptoms if pH is off. In soil, the nutrient availability window is 6.0–7.0, with sweet spots for different elements at different points in that range. Coco coir and hydro run tighter: 5.8–6.3. Even 0.3 pH units outside these ranges causes lockout — the nutrients are physically present but unavailable to roots.
Iron deficiency (interveinal yellowing on new growth) is almost always a pH problem, not an iron problem. Same with calcium and magnesium issues in coco. Fix pH first, then reassess. Check pH every feed and calibrate your meter monthly — cheap pH pens drift fast and will silently destroy your grows.
Reading Deficiency Symptoms Against Your Cannabis Nutrient Chart
Deficiency symptoms have a pattern: mobile nutrients (N, P, K, Mg) show in old leaves first because the plant moves them upward to newer growth. Immobile nutrients (Ca, Fe, Mn, B) show in new growth first because they can't be relocated once deposited.
- Lower leaf yellowing, uniform: Nitrogen deficiency — increase N or check pH around 6.5
- Dark/purple leaves, slow growth: Phosphorus deficiency — more common in cold root zones below 60°F
- Brown leaf edges, tip curl: Potassium deficiency or potassium lockout from excess calcium
- Interveinal yellowing on old leaves: Magnesium — add Epsom salt at 1–2g/L
- Interveinal yellowing on new leaves: Iron — almost always a pH issue, correct to 6.2–6.5
- Distorted new growth, brown tips on young leaves: Calcium — add Cal-Mag, check pH
Don't stack corrections. Fix pH first, wait 48–72 hours, then reassess before adding supplements. The Nutrient Deficiency Identifier walks you through a decision tree to nail diagnosis without guesswork.
Choosing a Nutrient Line: Budget vs. Premium
Budget Pick: General Hydroponics Flora Series
The three-part Flora Series (Micro, Grow, Bloom) has been the benchmark for decades. It works in every medium, the EC scales predictably, and the published mixing ratios are well-documented. For a single plant or a small tent, this is the most cost-effective option available. Expect to spend $30–50 for a full grow. Pair with Cal-Mag in soft water or coco environments.
Mid-Range Pick: Canna Coco A+B (for coco) / Fox Farm Trio (for soil)
If 63% of Grow Guide journal growers are in soil, Fox Farm's Grow Big, Big Bloom, Tiger Bloom trio is the most referenced feeding system in the community for good reason — it's forgiving, widely available, and the schedule cards are clear. Canna Coco A+B is purpose-built for coco coir, with pre-chelated micronutrients and calcium levels specifically calibrated for the medium's unique chemistry. Both lines run $60–90 for a grow and offer more headroom than the budget options.
Premium Pick: Athena Pro Line
Athena has become the go-to for serious indoor growers and commercial operations. The two-part system (Core + Bloom) mixes clean, EC is highly consistent batch-to-batch, and the company publishes detailed feed charts with EC targets for every stage. It's designed for coco drain-to-waste — which mirrors the top_feed_drain_to_waste workflow used by 12.6% of Grow Guide growers. More expensive upfront but lower waste per feed than many 5–7 bottle lines.
For organic growers, see our Best Organic Nutes for Cannabis 2026 guide for a separate breakdown of compost teas, dry amendments, and living soil programs.
Tracking Your Feeds — Don't Wing It
The best cannabis nutrient chart in the world is useless if you're not recording what you actually feed. Logging EC, pH, runoff EC, and plant response after every feed gives you a dataset to troubleshoot against. Growers who journal consistently catch problems 3–5 days earlier than those who don't. Start a grow diary — the How to Keep a Cannabis Grow Diary guide covers exactly what to record and when. Once you know your costs, run the numbers through the Cost Per Gram Calculator to see whether that premium nutrient line is actually paying off.
Frequently Asked Questions
What NPK ratio is best for cannabis in veg?
A ratio around 3-1-2 (N-P-K) works well for early veg, shifting to 2-1-2 in late veg. In practical terms, target a nitrogen-dominant feed with EC between 1.2–2.0 mS/cm. Keep soil pH at 6.0–7.0 or coco at 5.8–6.3 to ensure uptake.
Why are my plants showing deficiencies even though I'm feeding correctly?
pH drift is the most common cause — nutrients are present but locked out because the root zone pH is out of range. Check and correct pH first before adding more nutrients. Soil should be 6.0–7.0, coco 5.8–6.3. Recalibrate your pH meter if you haven't done so in the last 30 days.
Should I flush cannabis before harvest?
Tapering nutrients in the final 7–14 days is widely practiced and causes no harm — plain pH-adjusted water at EC 0.0–0.6 is the approach. Leaf yellowing during this period is the plant consuming its own stored nutrients, which is normal. Whether a full heavy flush meaningfully improves taste remains debated, but running clean water through the medium at the end of the cycle is a low-risk practice.
What's the difference between EC and PPM on a cannabis nutrient chart?
EC (electrical conductivity) is the base measurement in mS/cm or mS. PPM (parts per million) is a conversion of EC and varies by conversion factor — the 500 scale (multiply EC × 500) is common in North America, while the 700 scale (EC × 700) is used in Europe. Always check which scale your meter uses. EC 1.8 = approximately 900 PPM on the 500 scale, or 1260 PPM on the 700 scale.
How often should I feed cannabis versus just watering?
In soil, a common approach is feed-water-feed or feed-feed-water depending on how nutrient-rich your medium is. In coco running drain-to-waste, most growers feed every irrigation once established — daily or twice daily in late flower. Always water to at least 15–20% runoff to prevent salt buildup, and check runoff EC to monitor accumulation in the root zone.
