Nutrient Schedules & Troubleshooting HTML
Nutrient Schedules & Troubleshooting
This comprehensive guide will help you understand cannabis nutrients, develop feeding schedules, and quickly identify and fix common nutrient-related issues.
Understanding Cannabis Nutrients
Cannabis requires a variety of nutrients throughout its lifecycle, with different ratios needed during vegetative and flowering stages.
The Essential Macronutrients (NPK)
Nitrogen (N)
Function: Leaf development, vegetative growth, protein production
Deficiency Signs: Yellowing of older leaves from bottom up, stunted growth
Excess Signs: Dark green leaves, clawing, nutrient burn
When Needed Most: Vegetative stage
Phosphorus (P)
Function: Root development, energy transfer, flower formation
Deficiency Signs: Dark green leaves with purple stems, slow growth
Excess Signs: Nutrient lockout, causing other deficiencies
When Needed Most: Early flowering stage
Potassium (K)
Function: Water regulation, enzyme activation, carbohydrate production
Deficiency Signs: Yellow/brown leaf edges, weak stems
Excess Signs: Can block calcium and magnesium uptake
When Needed Most: Throughout flowering for bud development
Secondary Nutrients & Micronutrients
Calcium (Ca)
Function: Cell wall development, nutrient transport
Deficiency Signs: Curled new leaves, distorted growth, dead spots
When Needed: Throughout life cycle
Magnesium (Mg)
Function: Chlorophyll production, enzyme function
Deficiency Signs: Interveinal yellowing on older leaves
When Needed: Throughout life cycle, especially during flowering
Sulfur (S)
Function: Amino acid and protein synthesis
Deficiency Signs: Yellowing of new growth, stunted roots
When Needed: Throughout life cycle
Micronutrients
These are needed in very small amounts but are still essential:
| Micronutrient | Function | Deficiency Signs |
|---|---|---|
| Iron (Fe) | Chlorophyll synthesis | Yellowing between veins of young leaves |
| Manganese (Mn) | Enzyme function | Yellowing with small dead spots |
| Zinc (Zn) | Hormone production | Twisted new growth, smaller leaves |
| Boron (B) | Cell division | Brittle stems, hollow stems |
| Copper (Cu) | Enzyme activation | Blue-green leaves, limp growth |
| Molybdenum (Mo) | Nitrogen processing | Pale leaves with rolled edges |
Malta-Specific Nutrient Considerations
Malta's specific climate and water conditions create unique nutrient challenges:
Water Quality
- High pH: Malta's tap water typically has a pH of 7.5-8.5, significantly higher than the ideal 6.0-6.5 for cannabis in soil
- Calcium rich: High levels of calcium in water can contribute to nutrient lockout if not managed
- Solution: Use pH adjusters to lower water pH before feeding, or consider installing an RO (reverse osmosis) system for precise water control
Temperature Effects
- Summer heat: High temperatures (>30°C) reduce nutrient uptake efficiency
- Night cooling: Large day/night temperature swings can affect transpiration and nutrient movement
- Solution: Water during cooler morning hours, reduce nutrient strength during extreme heat by 25%
Humidity Challenges
- Salt buildup: Malta's high evaporation rates can increase salt accumulation in soil
- Transpiration fluctuations: Varying humidity levels affect nutrient uptake
- Solution: Flush growing medium more frequently than in other climates (every 2-3 weeks recommended)
Downloadable Feeding Schedules
Below are comprehensive feeding schedules for both autoflowering and feminized plants, optimized for Malta's growing conditions.
Autoflower Feeding Schedule
This schedule is designed for autoflowering plants with an 8-10 week lifecycle from seed to harvest. Adjust based on your specific strain and growing medium.
| Week | Stage | NPK Ratio | EC Range | Feed Frequency | Notes |
|---|---|---|---|---|---|
| 1 | Seedling | None | 0.0-0.2 | Water only | pH 6.0-6.5, light watering around seedling |
| 2 | Early Veg | 2-1-1 | 0.2-0.4 | Every other watering | ¼ strength nutrients, focus on root development |
| 3 | Vegetative | 3-1-2 | 0.4-0.8 | Every watering | ½ strength nutrients, add CalMag if needed |
| 4 | Late Veg | 3-2-3 | 0.8-1.0 | Every watering | ½-¾ strength, prepare for flowering transition |
| 5 | Pre-Flower | 2-2-3 | 1.0-1.2 | Every watering | Transition to bloom nutrients |
| 6 | Early Flower | 1-3-4 | 1.0-1.2 | Every watering | Full bloom nutrients, consider bloom booster |
| 7 | Mid Flower | 1-4-5 | 1.0-1.2 | Every watering | Peak bloom phase, monitor for nutrient sensitivity |
| 8 | Late Flower | 0-3-5 | 0.8-1.0 | Every watering | Reduce nitrogen completely, focus on ripening |
| 9 | Ripening | None | 0.0 | Water only | Begin flush with pH-adjusted water |
| 10 | Harvest | None | 0.0 | Water only | Continue flush, prepare for harvest |
Nutrient Deficiency Visual Guide
Use this interactive guide to identify nutrient deficiencies by their visual symptoms.
Nitrogen (N)
Symptoms:
- Yellowing of older, lower leaves first
- Entire leaf turns pale, then yellow, progressing from bottom to top
- Slow growth, smaller leaves
- In severe cases, leaves may turn brown and fall off
Solutions:
- Add nitrogen-rich fertilizer (higher first number in NPK)
- Use organic amendments like blood meal or fish emulsion
- Ensure proper pH (6.0-6.5 for soil) to allow nitrogen uptake
- Be careful not to overcorrect—too much nitrogen causes dark green leaves and clawing
Phosphorus (P)
Symptoms:
- Dark green leaves with purple/red stems
- Older leaves develop purple/red hue
- Stunted growth, especially in roots
- Small leaves and thin stems
Solutions:
- Add phosphorus-rich fertilizer (higher middle number in NPK)
- Organic options include bone meal or bat guano
- Ensure temperature isn't too cold (phosphorus uptake is reduced in cold conditions)
- Maintain proper pH (6.0-7.0) as phosphorus is less available at lower pH
Potassium (K)
Symptoms:
- Yellow/brown edges on older leaves first
- Curling leaf tips
- Weak stems and branches
- Increased susceptibility to disease and pests
Solutions:
- Add potassium-rich fertilizer (higher last number in NPK)
- Organic sources include wood ash (use sparingly) or kelp meal
- Avoid excessive calcium, which can block potassium uptake
- Maintain proper watering—both overwatering and underwatering can affect potassium availability
Magnesium (Mg)
Symptoms:
- Interveinal chlorosis (yellowing between leaf veins)
- Starts on older leaves and progresses upward
- Leaf veins remain green while areas between turn yellow
- Leaves may develop brown spots in advanced stages
Solutions:
- Apply Epsom salts (1 tablespoon per gallon of water)
- Use CalMag supplements
- For immediate relief, foliar spray with Epsom salt solution
- Avoid excessive potassium, which can compete with magnesium uptake
Calcium (Ca)
Symptoms:
- New leaves appear distorted or stunted
- Hook-like tips on leaves
- Brown/yellow spots between veins
- Dead spots on leaf edges
- Weak stems and roots
Solutions:
- Add CalMag supplement
- Use agricultural lime for soil grows (not during flowering)
- Maintain proper pH (6.0-6.5 for soil) for calcium availability
- Ensure adequate water as calcium moves through transpiration
Iron (Fe)
Symptoms:
- Interveinal yellowing on youngest leaves first
- Veins remain green while leaf tissue turns yellow
- Begins at top of plant (opposite of magnesium)
- Stunted growth in severe cases
Solutions:
- Use chelated iron supplements
- Lower pH slightly—iron is more available at slightly lower pH
- Reduce overwatering, which can limit oxygen and iron uptake
- Avoid excess phosphorus, which can bind with iron
Zinc (Zn)
Symptoms:
- New growth appears stunted and/or twisted
- Smaller than normal leaves
- Interveinal chlorosis similar to iron deficiency
- Leaves may take on a "rosette" pattern
Solutions:
- Use micronutrient supplements containing zinc
- Adjust pH to proper range (zinc availability decreases at higher pH)
- Foliar sprays with zinc can provide quick relief
- Avoid excessive phosphorus, which can block zinc uptake
Sulfur (S)
Symptoms:
- Entire leaf turns light green to yellow, including veins
- Begins with younger leaves first
- Slow overall growth
- Stems may turn purple
Solutions:
- Use fertilizers containing sulfur
- Epsom salts (magnesium sulfate) can address both magnesium and sulfur
- Maintain proper pH (6.0-6.5 for soil)
- Organic matter and compost often contain adequate sulfur
Common Nutrient Problems & Fixes
Nutrient Burn
Nutrient burn occurs when plants receive excessive nutrients, causing fertilizer salts to build up and "burn" the plant.
Symptoms:
- Yellow/brown leaf tips that look burnt
- Leaf tips curl upward and become crispy
- Dark green, "clawed" leaves (especially with nitrogen toxicity)
- In severe cases, entire leaf edges burn and leaves may die
Causes:
- Feeding at too high concentration
- Feeding too frequently
- Accumulation of nutrients in soil over time
- Feeding young plants at rates meant for mature plants
Solutions:
- Flush immediately: Drench the growing medium with pH-adjusted water (2-3 times the pot volume)
- Reduce strength: Once recovered, resume feeding at 50% of previous strength
- Monitor runoff EC: Check EC/PPM of water draining from pots
- Allow drying: Let the medium dry out more between waterings
- Adjust schedule: Consider feeding every other watering rather than every time
Malta-Specific Tip
In Malta's hot climate, nutrient solutions can become more concentrated as water evaporates quickly. Consider using slightly more diluted solutions (25% less concentrated) during summer months.
Nutrient Lockout
Nutrient lockout occurs when nutrients are present in the growing medium but unavailable to the plant due to pH issues or nutrient imbalances.
Symptoms:
- Multiple deficiency symptoms appearing simultaneously
- Symptoms persist despite feeding
- Yellowing leaves despite adequate feeding
- Stunted growth
- Salt buildup visible on soil surface or pot edges
Causes:
- pH imbalance (most common cause)
- Salt buildup from accumulated fertilizers
- Nutrient antagonism (excess of one nutrient blocking others)
- Poor soil drainage or compaction
Solutions:
- Check pH first: Test both input water/solution and runoff
- Complete flush: Flush with 3x pot volume of pH-adjusted water
- Reset pH: Adjust to proper range (6.0-6.5 for soil, 5.5-6.2 for coco/hydro)
- Wait before refeeding: Allow 1-2 waterings with just pH-adjusted water after flush
- Resume at lower strength: Start feeding at 25-50% strength
- Consider substrate: If problem persists, growing medium may need to be replaced
Malta-Specific Tip
Malta's alkaline water can quickly push growing media out of optimal pH range. Check runoff pH weekly to catch potential lockout issues early, especially when using tap water.
pH Imbalance
Proper pH is critical for nutrient availability. When pH drifts too far from optimal range, nutrients become unavailable to plants even when present in the medium.
Optimal pH Ranges:
- Soil: 6.0-7.0 (ideal 6.3-6.8)
- Coco/Peat: 5.5-6.5 (ideal 5.8-6.2)
- Hydroponic: 5.5-6.2 (ideal 5.8-6.0)
Symptoms of pH Problems:
- Too Low (Acidic): Calcium, magnesium deficiencies; stunted growth
- Too High (Alkaline): Iron, zinc, manganese deficiencies; yellowing new growth
- Multiple, seemingly unrelated deficiencies appearing together
- Nutrient issues that don't respond to feeding
Nutrient Availability Chart by pH
Solutions:
- Test regularly: Check both input solution and runoff
- Adjust input water: Use pH Up/Down to achieve target range
- Flush if necessary: For severe imbalances, flush with pH-adjusted water
- Buffer growing medium: Consider adding dolomite lime to soil to stabilize pH
- Malta-specific: Pre-treat tap water and let it sit 24 hours before pH adjustment
Malta-Specific pH Management
Malta's tap water typically has a pH of 7.5-8.5, requiring significant pH adjustment for cannabis cultivation. Consider:
- Using distilled water or rainwater collection during winter months
- Adding a small amount of vinegar (organic approach) to reduce pH
- Using commercial pH Down products (phosphoric acid based)
- Adding a buffering agent like pH stabilizer for maintaining consistent levels
Calcium & Magnesium Issues
Calcium and magnesium deficiencies are among the most common issues for cannabis growers, especially when using purified water or coco coir.
Calcium Deficiency Symptoms:
- New leaves appear distorted or stunted
- Brown/yellow spots between veins
- Dead spots on leaf edges
- Weak stems and roots
- Slow overall growth
Magnesium Deficiency Symptoms:
- Interveinal yellowing (yellowing between leaf veins)
- Starts on older leaves and progresses upward
- Leaf veins remain green while areas between turn yellow
- Leaves may develop brown spots in advanced stages
Common Causes:
- Using RO or distilled water without supplementation
- Growing in coco coir without CalMag
- pH imbalance (too low for Ca, too high for Mg)
- Excess potassium blocking calcium uptake
- High EC preventing proper calcium mobility
Solutions:
- Use CalMag supplement: 1-2ml per liter in every feeding for coco, or as needed for soil
- Check water source: Malta's tap water is usually high in calcium but may lack magnesium
- Adjust pH: Ensure proper range (6.0-6.5 for soil) as calcium is less available at lower pH
- Foliar spray: For immediate relief, use CalMag as foliar spray at ¼ strength
- Epsom salts: For magnesium-specific issues, add 1 teaspoon per gallon
Malta-Specific Note
Malta's hard water is usually calcium-rich but may still require magnesium supplementation. If using tap water, you may only need to add magnesium sulfate (Epsom salts) rather than a complete CalMag supplement.