NPK 9-3-6 Foliage Fertilizer Calculator
Use the NPK calculator pre-loaded with the 9-3-6 foliage-focused 3:1:2 liquid ratio.
Quick Answer
NPK 9-3-6 is a foliage-focused liquid fertilizer analysis containing 9% Nitrogen (N), 3% Phosphate (P₂O₅), and 6% Potash (K₂O) — a 3:1:2 ratio. In elemental terms, it provides 9% N, 1.3092% P, and 4.9812% K. Use the calculator above to compute exact fertilizer mass and elemental PPM delivery for your foliage plants.
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Enter your details below to generate a custom recommendation.
Recommended Output
Fertilizer to Add
Nitrogen (N)
Phosphate (P₂O₅)
Potash (K₂O)
The Problem
Most NPK calculators online are built for field-scale agriculture — hectares, acres, kg/ha, Urea/DAP/MOP. Home growers with a bottle of liquid feed and a windowsill of houseplants need a calculator scaled to a watering can or a single pot, not a wheat field.
When to Use This Tool
Use this calculator when you want to measure fertilizer according to a manufacturer's label rate, intentionally dilute that rate (e.g. half or quarter strength for sensitive plants), or calculate the fertilizer amount needed to reach a specific nitrogen concentration (ppm).
Who is this for?
- Houseplant growers
- Container gardeners
- Small-scale home growers
Guaranteed Analysis vs. Elemental Breakdown
Fertilizer packaging labels list nutrient content as nitrogen (N), phosphate (P₂O₅), and potash (K₂O). The actual elemental nutrient availability in solution is derived using standard conversion factors (P = P₂O₅ × 0.4364, K = K₂O × 0.8302).
| Nutrient Element | Guaranteed Label Analysis | Elemental Equivalent |
|---|---|---|
| Total Nitrogen (N) | 9% | 9% N |
| Available Phosphate (P₂O₅) → Elemental P | 3% P₂O₅ | 1.3092% P |
| Soluble Potash (K₂O) → Elemental K | 6% K₂O | 4.9812% K |
Formula & Worked Calculation Example
Elemental P % = P₂O₅ % × 0.4364 = 3% × 0.4364 = 1.3092% P
Elemental K % = K₂O % × 0.8302 = 6% × 0.8302 = 4.9812% K
Product Mass (g) = (Target N ppm × Volume L) / (N % × 10)
Elemental P ppm = Target N ppm × (Elemental P % / N %)
Elemental K ppm = Target N ppm × (Elemental K % / N %)
Benchmark Worked Example (100 ppm N in 10 Liters)
- Required Mass: (100 ppm × 10 L) / (9% × 10) = 11.111 g product
- Delivered N Concentration: 100.00 ppm N
- Delivered Elemental P Concentration: 100 ppm × (1.3092% / 9%) = 14.55 ppm P
- Delivered Elemental K Concentration: 100 ppm × (4.9812% / 9%) = 55.35 ppm K
Calculated Nutrient Delivery at Target Nitrogen Concentrations
Mathematical dilution scenarios based on guaranteed analysis. This table illustrates solution delivery and is not a universal feeding recommendation.
| Target N (ppm) | Product Mass (g / 10 L) | Delivered N (ppm) | Delivered Elemental P (ppm) | Delivered Elemental K (ppm) |
|---|---|---|---|---|
| 50 ppm | 5.556 g | 50.00 ppm | 7.27 ppm | 27.67 ppm |
| 100 ppm | 11.111 g | 100.00 ppm | 14.55 ppm | 55.35 ppm |
| 150 ppm | 16.667 g | 150.00 ppm | 21.82 ppm | 83.02 ppm |
| 200 ppm | 22.222 g | 200.00 ppm | 29.09 ppm | 110.69 ppm |
Sibling NPK Grade Comparison
Comparing fertilizer mass and elemental delivery across common NPK grades when mixed to a 100 ppm Nitrogen target in 10 Liters of water:
| NPK Grade | Ratio Class | Required Mass (10L @ 100ppm N) | Elemental P | Elemental K |
|---|---|---|---|---|
| NPK 10-10-10 | Balanced 1:1:1 | 10.00 g | 43.64 ppm | 83.02 ppm |
| NPK 20-20-20 | Balanced 1:1:1 (Concentrated) | 5.00 g | 43.64 ppm | 83.02 ppm |
| NPK 12-4-8 | Foliage 3:1:2 | 8.33 g | 14.55 ppm | 55.35 ppm |
What Is NPK 9-3-6 Fertilizer?
NPK 9-3-6 is a liquid concentrate foliage fertilizer analysis containing 9% Nitrogen (N), 3% Phosphate (P₂O₅), and 6% Potash (K₂O). Dividing the analysis values by 3 reveals a 3:1:2 ratio, matching the general nutrient uptake proportions of tropical Aroids and leafy houseplants.
Converting label oxide numbers to elemental mass, 100g of 9-3-6 provides 9.0g of Nitrogen (N), 1.3092g of elemental Phosphorus (P), and 4.9812g of elemental Potassium (K).
Why 3:1:2 Liquid Concentrates Are Popular
Leafy tropical houseplants consume nitrogen and potassium in greater quantities than phosphorus. Using a 3:1:2 ratio like 9-3-6 supplies sufficient nitrogen for lush green growth while preventing phosphorus accumulation in closed container pots.
Using This Calculator with NPK 9-3-6
This page pre-loads 9-3-6 into the calculator. To mix for 100 ppm N in 10 L of water, the calculator determines that 11.111 g of 9-3-6 product delivers 100 ppm N, 14.55 ppm elemental P, and 55.35 ppm elemental K.
Application Guidance
Apply 9-3-6 during active growth. Dilute carefully according to label instructions or target PPM, and ensure indoor plants receive adequate light to support nitrogen utilization.
Agronomic Context & Application Guidelines
Primary Utilities
- •Liquid concentrate container feeding for tropical foliage plants
- •Vegetative canopy expansion support where nitrogen and potassium demand exceeds phosphorus
- •Foliage maintenance in media with adequate baseline nutrient status
Limitations & Cautions
- •Not formulated for high-phosphorus or high-potassium reproductive fruit/flower demands
- •Adequate light is required to utilize supplied nitrogen without causing weak, stretched growth
- •Accurate liquid measurement is essential in small closed containers to manage root-zone salinity
Application Risk Factors
- •vegetative elongation under low light
- •substrate salt accumulation in small container media
- •soft leaf tissue expansion if over-fed
Common Calculation & Application Pitfalls
- Applying foliage-dominant fertilizer to flowering crops expecting increased bud initiation
- Over-dosing liquid concentrate drops in containers lacking drainage
- Assuming plant tissue uptake always matches the 3:1:2 formulation ratio exactly
Relevant Plant Care Guides
Discover specific care guidelines, light levels, and watering schedules for species suited to this NPK ratio class:
Troubleshooting & Diagnostics Guide
1 Stems are becoming leggy after feeding.
Diagnosis: High nitrogen application in low indoor light conditions.
Treatment: Increase bright indirect light or reduce fertilizer strength.
Glossary of Terms
- PPM (Parts Per Million)
- A measurement of concentration. For dilute aqueous solutions, 1 ppm is commonly expressed as approximately 1 mg/L.
- N-P₂O₅-K₂O
- The nutrient-analysis convention used on fertilizer labels for nitrogen, phosphate expressed as P₂O₅, and potash expressed as K₂O.
- Half Strength
- Using 50% of a fertilizer's label-recommended dose for the same water volume, a common practice for houseplants to reduce the risk of salt buildup in containers.
Frequently Asked Questions
What does NPK 9-3-6 mean?
What is the elemental P and K breakdown of 9-3-6?
Scientific References
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Source: homegarden.cahnr.uconn.edu