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Blooming (Main Flowering)

The Blooming Phase is the pinnacle of cannabis cultivation, where plants dedicate all their energy to producing buds. This phase requires precise nutrient management, stable environmental conditions, and careful monitoring to maximise yield, resin production, and overall bud quality.

Environmental and medium-specific parameters

Parameter Ideal range
Water pH (Soil) 6.0–6.5
Water pH (Coco Coir) 5.7–6.2
Water pH (Hydroponics) 5.5–6.0
EC Soil (mS/cm) 1.8–2.2
EC Coco Coir (mS/cm) 2.0–2.4
EC Coco Hydroponics (mS/cm) 2.2–2.6
Day Temperature (°C/°F) 24–26°C / 75–79°F
Night Temperature (°C/°F) 18–22°C / 64–72°F
Root Zone Temperature (°C/°F) 20–24°C / 68–75°F
Leaf Surface Temperature (°C/°F) 24–26°C / 75–78°F
Related Humidity (RH%) 40–50%
VPD (kPa) 1.2–1.5
Optimal CO₂ (ppm) 1200-1500
PAR (μmol/m²/s) 900-1200
Lights Hrs/Day 12/12 (Photoperiod) or unchanged for Autoflowers
Light Intensity (%) 90–100
Light Distance (cm/in) 20–40 cm / 8–16 in
Substrate Moisture Moist but not waterlogged
Primary Nutrients N, P, K (medium-high)
Secondary Nutrients Ca, Mg, S (high)
Micronutrients Fe, Zn, Mn, B, Cu, Mo
N-P-K 1–4–4
LST ScrOG, Trellis, Light Bending
HST None

Watering parameters

Key activities

  1. Monitor bud development
    Regularly inspect trichomes with a magnifying tool to assess maturity.
  2. Nutrient management
    Focus on phosphorus and potassium for flower formation while reducing nitrogen to prevent leafy growth.
  3. Humidity reduction
    Lower humidity levels to minimise mould and mildew risk.
  4. Support heavy branches
    Use stakes, trellis nets, or string to support buds as they gain weight.
  5. Pest and disease prevention
    Stay vigilant against pests and fungi that thrive in humid environments.
  6. Enhance resin production
    Consider UV supplementation and terpenoid-boosting products for increased potency.

What to watch out for

  1. Mould and mildew
    Dense buds and high humidity are prime conditions for mould growth.
  2. Light stress
    Avoid excessive light intensity that may bleach buds or cause foxtailing.
  3. Overfeeding
    Excess nutrients can cause buildup, leading to nutrient lockout or toxicity.

What to avoid

  1. Late-stage training
    Avoid heavy pruning or training as this can stress plants and reduce yield.
  2. High humidity
    Keep levels below 50% to prevent bud rot.
  3. Neglecting lower bud sites
    Defoliate strategically to improve airflow without over-pruning.

Nutrient needs

High phosphorus and potassium drive bud growth and resin production. Calcium and magnesium continue to play a supportive role in cell wall integrity and photosynthesis. Minimise nitrogen intake to avoid airy, less dense buds.

End-of-phase goals

Medium Frequency Volume (ml/L) Runoff %
Soil Every 2–3 days 400–550 10–20%
Coco Coir Daily 450–600 20–25%
Hydroponics Continuous Maintain aeration Ensure reservoir
Milestones Fully developed buds covered in trichomes.
Milky trichomes with occasional amber hints (for early ripening).
Plants structurally supported and free of pests or diseases.
Checklist Canopy evenly distributed with optimal light exposure.
Trichomes monitored for ripeness using a magnifier.
Humidity and temperature maintained at ideal levels.
Nutrients adjusted to focus on phosphorus and potassium.
Foxtailing

Foxtailing is a phenomenon where buds develop long, thin, and spire-like formations that resemble the tail of a fox. This growth pattern can occur for various reasons and may have positive or negative implications depending on the context.

Frequently asked questions

A recap with plenty of useful information

The blooming phase is when plants focus all their energy on producing flowers or buds.

Use a 12/12 light schedule for photoperiod plants; autoflowers remain on their existing schedule.

Focus on nutrients high in phosphorus and potassium, while reducing nitrogen.

Keep temperatures between 24–26°C (75–79°F) and humidity between 40–50%.

Avoid high-stress training; you can use low-stress methods like light bending or ScrOG adjustments.

Use a magnifying tool to inspect trichomes and watch for pistil darkening as maturity progresses.

Ensure proper airflow, keep humidity below 50%, and inspect plants regularly for signs of mould.

Light defoliation is acceptable, but avoid removing too many leaves to prevent plant stress.

Use UV light supplementation and terpenoid boosters, and maintain proper nutrient and environmental conditions.

Use trellis nets, stakes, or string to prevent branches from breaking under the weight of heavy bu

Gradually reduce nitrogen and increase phosphorus and potassium, monitoring EC levels.

Yes, if using enhanced CO₂, maintain levels between 1200–1500 ppm to boost bud growth.

Inspect trichomes using a magnifying tool; look for a transition from clear to milky, with some amber appearing.

Yes, lower night temperatures slightly and keep humidity below 50% to preserve terpenes.

Ensure excellent airflow, keep humidity low, and inspect buds regularly for any signs of rot.

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