Nutrient Schedule Generator

GH FloraSeries or Advanced Nutrients pH Perfect. Both are liquid (easier to measure with a syringe than dry nutrients with a scale), widely available, and well-documented in every grower forum. GH FloraSeries has the lowest barrier — three bottles, clear label, $40 starter set. Advanced Nutrients costs more but the pH-buffering feature means skipping one of the harder manual steps. Jack's 321 is the best value long-term (~$0.20 per gallon of finished nutrient vs ~$0.50 for GH) but requires a 0.1g gram scale and more careful mixing — better for your second grow after you understand the feedback loop.

Three feedback signals. EC meter reading — after mixing, EC should land within ±0.2 mS/cm of the target shown in the schedule. If you're consistently low, either your scale/syringe is off or your water has lower starting EC than assumed. Plant response over 7–10 days — healthy color, steady growth, no tip burn or yellowing. Runoff EC (soil and coco) — what comes out the bottom of the pot tells you how much salt is accumulating. If runoff EC climbs above feed EC week over week, you're overfeeding. Use our Feed Health Tracker tool for structured runoff analysis.

Set flower weeks to 10 in the tool — the schedule auto-adjusts. Longer flower cycles get more mid-flower weeks (the peak bud-development stage); the transition and flush weeks stay fixed at 1–2 weeks regardless. A 10-week flower typically breaks down as: 2 weeks transition, 2 weeks early flower, 3 weeks mid flower, 2 weeks late flower, 1 week flush. Sativa-dominant strains often flower 10–12 weeks; indica-dominant strains often 7–9 weeks. Always check the breeder's specification first.

Mostly yes, with adjustments. Autos flower automatically at ~3–4 weeks regardless of light cycle, so veg weeks should be set to 3–4, not longer. Their total life cycle is 10–12 weeks, so flower weeks typically 6–8. Autos are also more sensitive to overfeeding — many growers run autos at 60–70% of the schedule's dose. Start at the tool's recommendation, watch carefully for tip burn in the first 2 weeks of flower, and back off to 70% strength if you see any yellowing. Autoflower grows are less forgiving than photoperiod — less time to recover from feeding mistakes.

Three likely causes. Your water isn't zero EC — tap water typically has 0.2–0.6 mS/cm of dissolved minerals before you add anything. The tool targets are nutrient-added EC; add your source water EC to the target to get expected final reading. If tap is 0.4 and target is 2.0, your meter should read ~2.4 after mixing. Overdosing nutrients — a 0.5mL syringe miscount on a 5mL dose is 10% high. Use a precise syringe, double-check doses. Medium sensor — some PPM/EC meters drift with age; calibrate monthly with a 1.413 mS/cm standard solution.

Yes, and it's actually debated. The traditional view says flushing (pH-water only for the last 1–2 weeks) improves taste and burn quality by removing accumulated salts before harvest. The counter-view says properly-fed plants don't need flushing — salt buildup is a feeding-mistake issue, not a baseline state. Many commercial growers skip flush entirely and report no taste difference. The middle ground: if you've been overfeeding or your runoff EC has climbed, flush for 7–10 days to bring runoff EC below 1.0. If you've been careful with feeding and runoff EC stays close to feed EC, flush 3–5 days or skip entirely. Our tool schedules 1 week flush by default — you can treat it as optional.

RO (reverse osmosis) water has nearly zero dissolved minerals — including calcium and magnesium that plants need. Regular tap water provides 20–40ppm of calcium and 10–20ppm of magnesium from the water itself; RO strips all of that. Feeding plants in RO without Cal-Mag supplementation produces rapid calcium and magnesium deficiencies (reddish leaf stems, interveinal chlorosis in mid-to-upper leaves, tip curling) within 2 weeks. A dedicated Cal-Mag product (typically 3-0-0 with 2% Ca + 1% Mg) added at 3–5mL per gallon replaces what RO removed. Coco coir grows also need Cal-Mag because coco's cation exchange actively strips calcium from whatever solution touches it, even with tap water. When the tool flags a Cal-Mag warning, take it seriously.

Optional. Base nutrients already contain phosphorus and potassium — a separate PK booster adds more during peak bud development (weeks 4–6 of flower for most strains). The yield difference from adding a PK booster is real but modest — 5–10% on average in community comparison grows. More impactful for heavy-feeding strains, less for light feeders. If you're on a budget, skip it. If you're chasing maximum yield and have the base schedule dialed in, a PK booster during mid-flower is a ~$30 investment that returns 5–10% more bud weight. Never overdose — overfeeding P or K causes calcium and magnesium lockout (secondary deficiency) even when your base nutrients are correct.