Contents
Nutrient Requirements by Stage
Cannabis nutrient needs change significantly throughout the plant’s life cycle. These guidelines provide a starting point that can be adjusted based on specific genetics, growing medium, and environmental conditions.
Growth Stage Requirements (Soil/Coco)
| Growth Stage | N | P | K | Ca | Mg | S | EC Range (mS/cm) | pH Range | Watering Frequency |
|---|
| Seedling (weeks 1-2) | Very Low | Low | Low | Low | Low | Low | 0.4-0.8 | 5.8-6.3 | Low - when dry |
| Early Veg (weeks 3-4) | Medium | Low | Low | Low | Low | Low | 0.8-1.2 | 5.8-6.3 | Medium - when top 1" dry |
| Mid Veg (weeks 5-6) | High | Medium | Medium | Medium | Medium | Medium | 1.2-1.8 | 5.8-6.3 | Regular - when top 2" dry |
| Late Veg (weeks 7+) | High | Medium | High | Medium | Medium | Medium | 1.8-2.2 | 5.8-6.2 | Regular - when top 2" dry |
| Early Flower (weeks 1-3) | Medium | High | Medium | High | Medium | Medium | 1.6-2.0 | 5.8-6.2 | Regular - when top 2" dry |
| Mid Flower (weeks 4-6) | Low | High | High | Medium | High | Medium | 1.8-2.2 | 5.8-6.2 | Regular - don’t let dry |
| Late Flower (weeks 7+) | Very Low | Medium | High | Medium | Medium | Medium | 1.4-1.8 | 5.8-6.2 | Reduced - allow to dry more |
| Flush (final 7-14 days) | None | None | None | Low | Low | Low | 0.0-0.6 | 6.0-6.5 | Regular with plain water |
Hydroponic Target PPM/EC Values
| Growth Stage | PPM (500 scale) | PPM (700 scale) | EC (mS/cm) | Notes |
|---|
| Seedling/Clone | 200-400 | 280-560 | 0.4-0.8 | Very sensitive to nutrient strength |
| Early Veg | 400-600 | 560-840 | 0.8-1.2 | Gradually increase from seedling levels |
| Mid Veg | 600-900 | 840-1260 | 1.2-1.8 | Monitor for signs of deficiency/toxicity |
| Late Veg | 900-1100 | 1260-1540 | 1.8-2.2 | Peak nitrogen demand period |
| Early Flower | 800-1000 | 1120-1400 | 1.6-2.0 | Transition to bloom nutrients |
| Mid Flower | 900-1100 | 1260-1540 | 1.8-2.2 | Peak phosphorus demand period |
| Late Flower | 700-900 | 980-1260 | 1.4-1.8 | Begin gradual reduction |
| Flush | 0-300 | 0-420 | 0.0-0.6 | Plain water or light flush solution |
NPK Ratio Guide
Commercial Nutrient Ratio Guide
| Growth Stage | Ideal NPK Ratio | Commercial Examples | Notes |
|---|
| Vegetative | 3-1-1, 4-1-3, 3-1-2 | Fox Farm Grow Big (6-4-4)
General Hydroponics Flora Micro+Grow | Higher nitrogen promotes leaf and stem growth |
| Early Flower | 1-2-2, 1-3-2, 2-2-3 | Fox Farm Tiger Bloom (2-8-4)
General Hydroponics Flora Micro+Bloom | Transition phase, increased P for flower formation |
| Mid/Late Flower | 0-3-4, 1-3-4, 1-4-5 | Fox Farm Big Bloom (0.01-0.3-0.7)
Advanced Nutrients Big Bud (0-1-3) | Higher K for bud development and density |
| Finishing/Ripening | 0-1-3, 0-2-4 | Ripen by General Hydroponics
Terpinator (0-0-4) | Minimal N, focus on ripening and terpene development |
Generic Fertilizer Selection Guide
| Fertilizer Type | NPK Ratio | Best For | Application Rate (per gallon) |
|---|
| All-Purpose | 5-5-5, 4-4-4 | Beginning growers | 1-2 tsp per gallon |
| Veg Specific | 8-4-4, 9-3-6 | Vegetative growth | 1-2 tsp per gallon |
| Bloom Booster | 1-10-7, 0-10-10 | Mid-flower development | ½-1 tsp per gallon |
| Finisher | 0-5-10, 1-5-8 | Late flower ripening | ½-1 tsp per gallon |
Hydroponic Solution Recipes
DIY Nutrient Solution (per 10 gallons)
| Stage | Base Formula | Calcium Source | Magnesium Source | Iron & Micros | Target EC |
|---|
| Vegetative | 2 tbsp Masterblend 4-18-38 | 2 tbsp Calcium Nitrate | 1 tbsp Epsom Salts | ¼ tsp Iron DTPA (optional) | 1.6-1.8 |
| Early Flower | 2 tbsp Masterblend 4-18-38 | 1.5 tbsp Calcium Nitrate | 1 tbsp Epsom Salts | ¼ tsp Iron DTPA (optional) | 1.8-2.0 |
| Mid Flower | 2 tbsp Masterblend 4-18-38 | 1 tbsp Calcium Nitrate | 1 tbsp Epsom Salts | - | 1.8-2.0 |
| Late Flower | 1.5 tbsp Masterblend 4-18-38 | ½ tbsp Calcium Nitrate | 1 tbsp Epsom Salts | - | 1.4-1.6 |
Modified Hoagland Solution (Hydroponic, ppm)
| Macronutrient | Vegetative | Early Flower | Mid Flower | Late Flower |
|---|
| Nitrogen (N) | 200-250 | 150-200 | 100-150 | 50-80 |
| Phosphorus (P) | 30-50 | 50-80 | 60-80 | 40-60 |
| Potassium (K) | 200-250 | 250-300 | 300-350 | 250-300 |
| Calcium (Ca) | 150-180 | 180-200 | 180-200 | 120-150 |
| Magnesium (Mg) | 40-50 | 50-60 | 50-60 | 40-50 |
| Sulfur (S) | 30-50 | 40-60 | 40-60 | 30-50 |
| Micronutrient | All Stages (ppm) |
|---|
| Iron (Fe) | 2-4 |
| Manganese (Mn) | 0.5-1.0 |
| Zinc (Zn) | 0.3-0.5 |
| Boron (B) | 0.3-0.6 |
| Copper (Cu) | 0.1-0.2 |
| Molybdenum (Mo) | 0.05-0.1 |
Organic Amendment Guide
| Amendment | N-P-K Approx | Application Rate | Release Speed | Best For |
|---|
| Worm Castings | 1-0-0 | 5-10% soil volume | Medium | General health, microbial life |
| Bat Guano (High N) | 10-3-1 | ½-1 cup | Medium-Fast | Vegetative growth |
| Bat Guano (High P) | 3-10-1 | ½-1 cup | Medium-Fast | Flowering boost |
| Blood Meal | 12-0-0 | ¼-½ cup | Fast | Nitrogen boost, vegetative |
| Bone Meal | 3-15-0 | ½-1 cup | Slow | Phosphorus source, flowering |
| Fish Meal | 8-6-0 | ½ cup | Medium | All-purpose growth |
| Kelp Meal | 1-0-2 | ¼-½ cup | Medium | Micronutrients, stress management |
| Alfalfa Meal | 3-1-2 | ½-1 cup | Medium | Growth stimulant, triacontanol |
| Neem Seed Meal | 6-1-2 | ¼-½ cup | Slow | Pest management, steady N |
| Langbeinite (K-Mag) | 0-0-22 | 2-3 tbsp | Medium | K, Mg and S source |
Liquid Organic Feeding (per gallon)
| Amendment | NPK Approx | Application Rate | Frequency | Best For |
|---|
| Compost Tea | varies | Full strength | Weekly | Microbial diversity, overall health |
| Worm Casting Tea | 1-0-0 | Full strength | Weekly | Gentle feeding, microbes |
| Fish Hydrolysate | 4-2-2 | 1-2 tbsp | Bi-weekly | Complete nutrition, vegetative |
| Fish Emulsion | 5-1-1 | 1 tbsp | Bi-weekly | Nitrogen boost, vegetative |
| Seaweed Extract | 0-0-1 | 1-2 tsp | Weekly | Micronutrients, stress management |
| Molasses | 1-0-5 | 1 tbsp | Bi-weekly | Microbe food, potassium source |
| Aloe Vera | trace | 2 tbsp fresh gel | As needed | Rooting, stress management |
| Coconut Water | trace | ¼ cup | As needed | Cytokinins, early flowering boost |
Deficiency & Toxicity Guide
Quick Visual Diagnosis
| Nutrient | Deficiency Symptoms | Mobility | Where Symptoms Appear First | Common pH Cause | Quick Fix (per gallon) |
|---|
| Nitrogen (N) | Yellowing leaves, older leaves first, slow growth | Mobile | Lower/older leaves | pH too high | 1 tsp calcium nitrate |
| Phosphorus (P) | Dark green leaves with purple/red edges, slow growth | Mobile | Lower/older leaves | pH too low or too high | 1 tsp monopotassium phosphate |
| Potassium (K) | Yellow/brown edges, necrotic spots | Mobile | Lower/older leaves | pH too high | 1 tsp potassium sulfate |
| Calcium (Ca) | New leaves twisted, dead spots, hook-tipped | Immobile | New growth/growing tips | pH too low | 1 tsp calcium nitrate |
| Magnesium (Mg) | Interveinal yellowing, edges and veins stay green | Mobile | Middle to lower leaves | pH too low | 1 tsp Epsom salts |
| Sulfur (S) | Light green/yellow new growth, similar to N but on new leaves | Immobile | New/upper growth | - | ½ tsp Epsom salts |
| Iron (Fe) | Interveinal yellowing of new leaves, veins stay green | Immobile | New/upper growth | pH too high | Foliar: 0.1 tsp iron chelate |
| Zinc (Zn) | Interveinal yellowing, small leaves, short internodes | Immobile | New leaves/growing tips | pH too high | Foliar: micronutrient mix |
| Manganese (Mn) | Yellowing between veins, speckling pattern | Immobile | New leaves | pH too high | Foliar: micronutrient mix |
| Boron (B) | Thick, distorted new growth, growing tips die | Immobile | Growing tips/new leaves | - | Foliar: 1/8 tsp borax (use with caution) |
| Growing Medium | Ideal pH Range | N | P | K | Ca | Mg | S | Fe | Mn | B | Cu & Zn |
|---|
| Soil | 6.0-6.8 | 6.0-8.0 | 6.0-7.5 | 6.0-9.0 | 6.5-9.0 | 6.5-9.0 | 5.5-9.0 | <7.0 | 5.5-7.5 | 5.0-9.0 | 5.0-7.5 |
| Coco/Soilless | 5.8-6.3 | 5.5-8.0 | 5.5-7.5 | 6.0-9.0 | 6.0-9.0 | 6.0-9.0 | 5.5-9.0 | <6.5 | 5.5-7.0 | 5.0-9.0 | 5.0-7.0 |
| Hydroponics | 5.5-6.2 | 5.0-8.0 | 5.0-7.5 | 6.0-9.0 | 5.5-9.0 | 5.5-9.0 | 5.5-9.0 | <6.0 | 5.0-7.0 | 5.0-9.0 | 5.0-7.0 |
Note: Numbers indicate pH ranges where nutrients are most available. For cannabis, staying in the ideal pH range ensures access to most nutrients.
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