The flowering stage is the most exciting phase of cannabis growth, where your plants start producing buds rich in THC, CBD, and terpenes. This stage requires strict environmental control, nutrient adjustments, and careful monitoring to maximize yield and potency.
1️⃣ What Happens During the Flowering Stage?
The flowering stage begins when the light cycle changes to 12/12 (12 hours light, 12 hours darkness). This triggers hormonal changes, signaling the plant to stop vegetative growth and focus on bud production.
🌿 Key Plant Changes:
✔ Stretching Phase – Plants can double in size 📏
✔ White Pistils Appear – Early signs of bud development
✔ Trichomes Form – Resin glands produce cannabinoids
✔ Buds Swell & Ripen – Final stage before harvest
💡 Goal: Maximize bud size, resin production, and potency before harvest.
2️⃣ Flowering Stage Timeline & Phases
The flowering phase typically lasts 7-12 weeks, depending on the strain.
📅 Week-by-Week Breakdown:
| Stage | Weeks | Changes |
|---|---|---|
| Pre-Flowering (Stretch Phase) | 1-2 | Plants grow rapidly, white pistils appear 🌱 |
| Early Flowering | 3-4 | Buds begin forming, trichomes start appearing ✨ |
| Mid-Flowering | 5-7 | Buds swell, resin production increases 🌼 |
| Late Flowering (Ripening Stage) | 8-12 | Trichomes turn cloudy/amber, pistils darken 🔬 |
💡 Pro Tip: Use a magnifying glass or jeweler’s loupe to monitor trichome color for peak potency.
3️⃣ Recognizing Flowering Stage Signs
🔍 Early Signs (Weeks 1-2)
✔ White hairs (pistils) appear on bud sites
✔ Plants stretch significantly (especially sativas)
✔ Increased smell as terpenes develop
🌿 Mid-Flowering Signs (Weeks 3-7)
✔ Dense bud formation begins
✔ Trichomes become sticky and shiny
✔ Leaves may yellow slightly as nitrogen use decreases
🌼 Late Flowering Signs (Weeks 8-12)
✔ Pistils darken from white to orange/brown
✔ Trichomes change from clear → cloudy → amber
✔ Buds reach maximum size and potency
💡 Harvest Timing: Harvest when trichomes are mostly cloudy with some amber for peak THC levels.
4️⃣ Flowering Stage Nutrients & Feeding Schedule
Cannabis needs lower nitrogen and higher phosphorus & potassium during flowering.
🌿 Ideal NPK Ratios for Flowering:
✔ Early Flowering (Weeks 1-4): 5-10-10 (Moderate PK Boost)
✔ Mid-Flowering (Weeks 5-7): 4-12-12 (Higher PK)
✔ Late Flowering (Weeks 8+): 0-10-10 (No Nitrogen, Maximum PK)
🌱 Feeding Schedule:
| Week | Nutrient Strength | NPK Ratio |
|---|---|---|
| 1-2 | 50% Strength | 5-10-10 |
| 3-4 | 75% Strength | 4-12-12 |
| 5-7 | 100% Strength | 4-12-12 |
| 8+ | Reduce Feeding | 0-10-10 |
🔹 pH Level: Maintain 6.0-6.5 (soil) and 5.5-6.0 (hydroponics) for nutrient uptake.
🔹 Stop feeding nutrients 1-2 weeks before harvest (flushing phase).
💡 Pro Tip: Use molasses (1 tsp per gallon of water) to enhance bud flavor and resin production.
5️⃣ Environmental Control During Flowering
Maintaining temperature, humidity, and airflow prevents mold and increases resin production.
🌡️ Temperature & Humidity Guidelines:
| Phase | Day Temp | Night Temp | Humidity |
|---|---|---|---|
| Pre-Flowering | 75-85°F (24-29°C) | 65-75°F (18-24°C) | 50-60% |
| Mid-Flowering | 70-80°F (21-27°C) | 60-70°F (15-21°C) | 45-55% |
| Late Flowering | 65-75°F (18-24°C) | 55-65°F (13-18°C) | 40-50% |
🔹 Lower humidity (40-50%) prevents bud rot and mold.
🔹 Increase airflow with oscillating fans for stronger stems.
🔹 CO₂ Enrichment (1000-1500 ppm) enhances bud production.
💡 Pro Tip: Gradually reduce night temperatures to enhance purple hues in certain strains.
6️⃣ Common Mistakes to Avoid 🚫
❌ Overfeeding Nutrients – Leads to nutrient burn (dark, curled leaves).
❌ High Humidity – Can cause bud rot (gray mold).
❌ Harvesting Too Early – Lowers potency and yield.
❌ Overwatering – Leads to root rot and slow bud growth.
❌ Ignoring Light Leaks – Interrupts the 12/12 cycle and causes stress.
💡 Pro Tip: Use lightproof grow tents or cover windows completely to avoid hermaphrodite plants.
7️⃣ Preparing for Harvest 🌿
Once trichomes turn cloudy with 10-20% amber, it’s time to flush and prepare for harvest.
✔ Final Steps Before Harvest:
✔ Flushing (Weeks 8-10): Stop nutrients and use only pH-balanced water.
✔ Lower Humidity to 40-45% to prevent mold in dense buds.
✔ Monitor Trichomes – Harvest when they are mostly cloudy.
✔ Prepare Drying Space – Dark, well-ventilated room with 50% humidity.
Final Thoughts
✅ Monitor pistils and trichomes to determine the perfect harvest time.
✅ Adjust feeding, lighting, and humidity for optimal bud development.
✅ Flush properly before harvest to enhance flavor and smoothness.
✅ Avoid common mistakes like overfeeding, overwatering, and high humidity.