The flowering phase is a critical period for cannabis and other flowering plants, where proper fertilization can make or break your harvest. But how often should you fertilize during this stage? Over-fertilizing can burn plants, while under-fertilizing may stunt growth. This guide breaks down optimal fertilization schedules, nutrient types, and pro tips to ensure robust blooms and healthy yields.
Why Fertilizing During Flowering Matters
During flowering, plants shift their energy from vegetative growth to bud development. Key nutrients like phosphorus (P) and potassium (K) become vital for resin production, terpene development, and dense buds. Nitrogen (N) is still needed but in smaller amounts. A balanced feeding schedule ensures plants thrive without nutrient lockout or deficiencies.
Optimal Fertilization Schedule for the Flowering Phase
Week 1-2: Transition Period
As plants enter pre-flowering, gradually reduce nitrogen and increase phosphorus. Feed every 3-4 days with a bloom-specific fertilizer (e.g., 5-10-5 NPK ratio).
Week 3-6: Peak Flowering
Plants demand more phosphorus and potassium. Fertilize every 2-3 days with a high-PK formula. Monitor pH levels (6.0–6.5 for soil, 5.5–6.0 for hydroponics) to ensure nutrient uptake.
Week 7-8: Flushing
Stop fertilizing 1–2 weeks before harvest. Flush plants with pH-balanced water to remove excess salts, improving flavor and smoothness.
Top 3 Fertilization Mistakes to Avoid
- Overfeeding: Excess nutrients cause leaf burn. Follow manufacturer guidelines.
- Ignoring pH Levels: Improper pH locks out nutrients. Test water regularly.
- Skipping Flushing: Residual nutrients harm flavor and potency.
Best Fertilizers for the Flowering Stage
- Organic Options: Bat guano, worm castings, or kelp meal.
- Synthetic Nutrients: Fast-acting formulas like Fox Farm Tiger Bloom.
- Supplements: Add cal-mag or molasses for secondary nutrients.
Signs Your Plants Need Adjustments
- Yellowing Leaves: Nitrogen deficiency.
- Burnt Tips: Nutrient burn (reduce feeding).
- Purple Stems: Phosphorus shortage.
FAQ
Q: Can I use vegetative fertilizers during flowering?
A: No—high nitrogen disrupts bud growth. Switch to bloom-specific formulas.
Q: How do I fix over-fertilization?
A: Flush soil with pH-balanced water and pause feeding for 5–7 days.