General Hydroponics Flora Series Feed Chart: Expert Feeding Schedule
Author: Faisal Habib |
Fact-Checked: Lab and Field Verified |
Expert Reviewer: Wara Danish, MSc Plant Biology
Mixing the 3-part General Hydroponics Flora Series requires following the Golden Mixing Order: fill your reservoir with water, add FloraMicro first and stir thoroughly until completely clear, then add FloraGrow, and finally add FloraBloom. Mixing concentrated Micro and Bloom directly causes calcium phosphate to precipitate into permanent, unusable crystals.
Nutrient precipitation fallout is the chemical bonding of calcium cations ($Ca^{2+}$) with sulfate ($SO_4^{2-}$) or phosphate ($PO_4^{3-}$) anions when concentrated fertilizer solutions mix prematurely. This reaction forms insoluble calcium sulfate (gypsum) or calcium phosphate crystals that settle to the bottom of the tank, permanently locking out essential macronutrients.
📜 Table of Contents — Click to Expand Navigation
- Regional Labeling Differences: International bottles may carry different NPK ratios than standard US versions; always calculate based on your local bottle label.
- Hard Tap Water Triggers Gypsum: Using municipal hard tap water without a hard-water Micro formula causes calcium and carbonate precipitation at high EC levels.
- Unmixed Water Pockets: Skipping a thorough 15-minute pump circulation cycle leads to dense, high-EC fertilizer pockets settling at the reservoir floor.
- Lucas Formula Phosphorus Excess: The Lucas Formula delivers high phosphorus that can cause premature bolting and bitterness in delicate leafy lettuce.
- Unbuffered Coco Coir Lockout: Failing to pre-buffer coco coir substrates allows the cation exchange complex to strip calcium, triggering tipburn.
Mixing the 3-part General Hydroponics Flora Series correctly is the single most critical factor for establishing a balanced, high-performance nutrient reservoir. Pumping concentrated minerals directly into a tank without understanding ion compatibility triggers chemical reactions that cause permanent nutrient precipitation, rendering key elements completely unavailable.
This guide provides the official, field-verified Flora Series feed chart for recirculating and drain-to-waste systems, details the famous Lucas Formula shortcut, and outlines specific pre-buffering protocols for reverse osmosis water and coco coir substrates.
1. The Golden Mixing Rule & Chemistry of Precipitation
The General Hydroponics Flora Series consists of FloraMicro (5-0-1), FloraGrow (2-1-6), and FloraBloom (0-5-4). Poured together in their concentrated forms, the divalent calcium ($Ca^{2+}$) cations in FloraMicro react instantly with the sulfate ($SO_4^{2-}$) and phosphate ($PO_4^{3-}$) anions in FloraBloom and FloraGrow.
This reaction produces calcium sulfate (gypsum) and calcium phosphate precipitates. These minerals form a white, chalky sediment that drops to the bottom of the reservoir, clogging drip lines and causing severe nutrient starvation.
Once precipitated, these elements are permanently locked out and cannot be redissolved. To prevent this, always add FloraMicro to the reservoir water first and stir completely until clear before adding FloraGrow and FloraBloom.
2. Master Flora Series Feeding Schedule
Recirculating systems (DWC, NFT) require slightly lighter concentrations (EC 1.2–1.8 mS/cm) than drain-to-waste substrates. In coco coir or rockwool, run higher concentrations (EC 1.8–2.2 mS/cm) as daily runoff washes away accumulated minerals.
| Growth Phase | FloraMicro | FloraGrow | FloraBloom | Target EC Range |
|---|---|---|---|---|
| Seedling / Rooting Clones | 2.5 mL | 2.5 mL | 2.5 mL | 0.6 – 0.8 mS/cm |
| Early Vegetative | 5.0 mL | 5.0 mL | 5.0 mL | 1.1 – 1.3 mS/cm |
| Aggressive Vegetative (Lettuce) | 7.5 mL | 10.0 mL | 2.5 mL | 1.5 – 1.8 mS/cm |
| Transition to Bloom | 7.5 mL | 7.5 mL | 7.5 mL | 1.6 – 1.9 mS/cm |
| Peak Flowering / Fruiting | 7.5 mL | 2.5 mL | 12.5 mL | 1.8 – 2.2 mS/cm |
| 🏆 Crop Application | Leafy greens and non-fruiting herbs should remain on the Aggressive Vegetative recipe for their entire life cycle. Transition fruiting tomatoes and peppers to the Peak Flowering recipe once primary floral clusters emerge. | |||
3. The Lucas Formula: Dosing, PPMs, and Leafy Greens
The Lucas Formula is a widely used dosing shortcut that drops FloraGrow entirely. It relies on a fixed ratio of 8 mL FloraMicro to 16 mL FloraBloom per US gallon. Because FloraMicro carries sufficient calcium, nitrogen, and iron, the plant gets everything it needs for vegetative development.
In pure RO water, this 8:16 ratio delivers approximately 130 ppm Nitrogen, 105 ppm Phosphorus, 185 ppm Potassium, 104 ppm Calcium, and 63 ppm Magnesium. It is ideal for fruiting crops but is too heavy in phosphorus for leafy greens, which do better on the standard 3-part vegetative schedule.
Target EC with the Lucas Formula is 1.8 to 2.0 mS/cm. Keep daily EC fluctuations under 0.2 mS/cm by topping off transpiration water losses with pure RO water before checking nutrient levels.
4. Water Source and Substrate Customizations
Pure reverse osmosis (RO) water has zero background minerals or buffering capacity, leaving solutions prone to wild pH swings. Reconstitute RO water to 0.3 to 0.4 mS/cm with a Cal-Mag supplement before adding FloraMicro.
Coco coir has a high cation exchange capacity (CEC) that binds calcium and magnesium while releasing potassium. If growing in coco, increase FloraMicro by 15% to 20% during the first 3 weeks of vegetative growth to satisfy the substrate’s high calcium demand.
| Water / Medium | Baseline EC | Key Mineral Challenge | Required Dosing Action |
|---|---|---|---|
| RO / Distilled Water | 0.0 mS/cm | Zero calcium, magnesium, or carbonate buffer | Add Cal-Mag to 0.3–0.4 mS/cm first |
| Hard Municipal Water | >0.5 mS/cm | Excess carbonates, calcium, and sodium | Use FloraMicro Hard Water formula |
| Raw Rainwater | 0.05 mS/cm | Acidic pH drift, zero mineral background | Treat identically to pure RO water |
| Coco Coir Substrate | N/A | Substrate CEC binds calcium and magnesium | Increase FloraMicro by 15% to 20% |
| 🏆 Best Practice | Always prepare your water baseline before adding any fertilizer concentrates. Pre-buffering with Cal-Mag or using hard-water Micro formulas prevents late-stage mineral lockout and stabilizes daily reservoir pH curves. | ||
🔧 Step-by-Step: How to Mix the General Hydroponics Flora Series
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1Add Silicon Supplements First
Fill your clean reservoir with water. If using a silicon supplement like Armor Si, add it first at 1.0 to 2.5 mL per gallon and stir thoroughly. Let the water sit for 5 minutes to fully dissolve before proceeding.
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2Dilute FloraMicro and Stir Until Clear
Measure the required dose of FloraMicro using a clean syringe. Slowly pour it into the water and stir until the solution is completely uniform and transparent. Never skip this step.
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3Add FloraGrow to the Mixture
Measure the required volume of FloraGrow. Pour it into the reservoir and stir thoroughly. FloraGrow supplies the nitrogen and potassium required for vegetative structural development.
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4Add FloraBloom to the Mixture
Measure and add FloraBloom to the reservoir, stirring completely. FloraBloom provides the concentrated phosphorus and sulfur required for flower development and root health.
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5Recirculate and Adjust Solution pH
Run your system pump for 15 minutes to homogenize the mixture. Test the pH and adjust back to the 5.8 to 6.3 target window using pre-diluted pH Up or pH Down.
5. Active Reservoir pH Drift and Nutrient Lockout
Reservoir pH drifts naturally as plants absorb nutrients. When crops consume negatively charged nitrate ($NO_3^-$) anions, roots excrete bicarbonate ($HCO_3^-$) ions to balance cellular charge, causing solution pH to rise.
Maintain active reservoir pH strictly between 5.8 and 6.3. Iron (Fe) and manganese (Mn) absorption is optimized at the lower end (5.8), while phosphorus (P) and molybdenum (Mo) favor the upper end (6.2).
If pH drifts outside this window, elements drop out of solution. This triggers severe nutrient deficiencies such as interveinal chlorosis. Test and calibrate your pH pen weekly using standard reference fluids.
6. Advanced Additives & Supplement Integration
Integrating additives can enhance root mass and secondary metabolite production. However, improper sequencing can cause these additives to react with your core fertilizer salts.
Potassium Silicate: Always add silicon to the water first and allow it to dissolve completely before adding FloraMicro. Introducing silicate after calcium or magnesium causes an insoluble mineral gel to form instantly.
- Precipitated Salts Cannot Be Saved: Once calcium and sulfate drop out of solution as white sediment, they are permanently bonded; you must drain and restart.
- Silicates Must Be Mixed First: Potassium silicate must dissolve completely in the water first, or it will bind with metals to create an unusable silica gel.
- Lucas Formula Ceilings for Greens: The 8:16 Micro/Bloom Lucas Formula is designed for heavy-fruiting crops; its high phosphorus level can cause premature bolting in leafy lettuce.
- DLI Drives Transpiration Stress: A high daily light integral combined with low humidity concentrates reservoir salts rapidly; dilute top-offs with pure RO water daily.
If you’ve mixed FloraMicro and FloraBloom out of order and see white flakes forming, do not try to fix the batch by adding acid or warm water. The calcium-phosphate bond is structurally permanent under normal parameters. Save your crop’s roots from salt stress: drain, flush with RO water, and mix a fresh batch.
Chemical handling precautions: Concentrated nutrient stock solutions and pH regulators are strong skin and eye irritants. Always wear nitrile gloves and protective eyewear when handling them. Never mix concentrated pH Down and silicon additives directly in the same measuring cup; they will react violently. Ensure all reservoir pumps are connected to a GFCI breaker.
- Mixing Concentrated Bottles Directly: Pouring Micro and Bloom together into a measuring cup ruins both concentrates instantly.
- Ignoring Post-Mixing pH Drift: Concentrates are highly acidic; neglecting to re-balance the reservoir after mixing causes severe acid root burn.
- Using Hard Tap Water as RO Buffer: Reconstituting RO water with hard tap water adds heavy carbonates, locking out phosphorus.
- Omitting the 14-Day Solution Dump: Indefinite top-offs without full drain cycles allow toxic sodium ions to accumulate to dangerous levels.
- Chasing Drift with Uncalibrated Probes: Adjusting reservoir parameters using dirty, drifting electrode pens can damage your plants.
✅ Key Takeaways & Final Summary
- Golden Rule: Add silicates first, then FloraMicro and stir until clear, then FloraGrow, and finally FloraBloom to prevent fallout.
- Target pH Window: Maintain reservoir pH at 5.8 to 6.3 to optimize both macro and micronutrient absorption.
- RO Pre-Buffering: Reconstitute pure RO water to 0.3 to 0.4 mS/cm with Cal-Mag before adding other fertilizers.
- Interactive Tools: Convert your target ppm into exact milliliter measurements using our free EC to PPM Converter.
- Reservoir Changes: Execute a 100% solution dump every 14 days to prevent mineral imbalances and salt buildup.
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❓ Frequently Asked Questions
All citations verified as of August 2026. Compliant with CurrentGardening 7-year freshness standard.
- University of Minnesota Extension — Small-Scale Hydroponic Nutrient Solutions and Mixing (2021)
- University of Florida IFAS — Nutrient Management and Ionic Balance in Soilless Culture (2022)
- Computers and Electronics in Agriculture — Automated Fertigation Control and Salt Accumulation Dynamics (2022)
- University of Arizona CEAC — CEA Reservoir Chemistry and Calcium Phosphate Pre-buffering (2023)
📋 Content Update History — Click to View
- August 26, 2026: Upgraded to Gatekeeper V14 specification: added consolidated single-line @graph JSON-LD schema with HowTo 5-step protocol, 2 full data tables, Lucas Formula elemental breakdown, custom 16:9 and 9:16 Pinterest pin visual assets, and 2021–2023 peer-reviewed citations. Authorship by Faisal Habib and review by Wara Danish.
- July 11, 2026: Initial publication covering General Hydroponics standard feeding charts.
📘 This guide is part of our Complete Guide to Hydroponics series — our master directory for soilless cultivation. Read the master pillar guide for comprehensive system comparisons, water chemistry blueprints, and complete crop-cycling workflows.
