Flowering stage management: from stretch to harvest

The flowering phase requires precise management for optimum results:

**Understanding flowering phase stages:**

*Pre-flower (week 1-2):*

- First signs of sexing

- Internode elongation begins

- Hormonal change

- Nutrient adjustment necessary

- Training still possible

*Early Flower (week 3-4):*

- Stretch phase fully developed

- First real flower formation

- Height increase 50-200%

- Structure finalised

- No more training

*Mid Flower (week 5-7):*

- Intensive flower development

- Maximum nutrient demand

- Resin production increases

- Weight gain of buds

- Optimum environmental control critical

*Late Flower (week 8+):*

- Flower maturation

- Trichome development

- Nutrient reduction

- Start flushing

- Harvest preparation

**Lighting for flowering phase:**

*12/12 light cycles:*

- Absolute darkness required

- Do not tolerate light leaks

- Timer precision critical

- Maintain constant times

- Avoid interruptions

*Light intensity flowering:*

- PPFD 600-1000 µmol/m²/s

- DLI 35-50 mol/m²/day

- Gradually increase over weeks

- Maximum in mid-flower

- Reduction before harvest optional

*Spectrum for flowering:*

- Red-emphasised spectrum (660-730nm)

- Promotes flower development

- Far-red for stretch control

- Full spectrum still optimal

- 2700K for HPS/CFL

**Flower nutrient management:**

*Flowering NPK ratio:*

- Phosphorus-emphasised (1-3-2)

- Reduced nitrogen

- Increased potassium

- Calcium/magnesium constant

- Micronutrients important

*Feeding schedule flowering:*

- Week 1-2: Transition nutrients

- Week 3-6: Full flowering dose

- Week 7+: Start reduction

- Last 1-2 weeks: Flush

- Adjust EC values accordingly

*Special bloom additives:*

- PK booster (phosphorus/potassium)

- Molasses for microbes

- Cal-Mag Supplements

- Silicon for structure

- Enzymes for root health

**Environmental control flowering:**

*Flowering temperature:*

- Day: 20-26°C (cooler than Vegi)

- Night: 16-20°C

- Temperature difference important

- Cooler nights promote colour development

- Avoid heat stress

*Flowering humidity:*

- Early Flower: 55-65% RH

- Mid Flower: 45-55% RH

- Late Flower: 40-50% RH

- Mould prevention is a priority

- Increase air circulation

*VPD management:*

- Optimal: 1.0-1.5 kPa

- Higher VPD than vegetative

- Promote transpiration

- Optimise nutrient transport

- Find stress balance

**Stretch management:**

*Stretch factors:*

- Genetics (Sativa > Indica)

- Light intensity and spectrum

- Temperature difference day/night

- Nutrient availability

- Training history

*Stretch control:*

- Increase light intensity

- Keep temperatures more constant

- Training in Pre-Flower

- Use SCROG nets

- Supercropping as an emergency

**Promote flower development

*Environmental optimisation:*

- Constant 12/12 cycles

- Optimum temperature/humidity

- Adequate air circulation

- Maintain CO2 levels

- Eliminate stress factors

*Nutrient timing:*

- Timely switch to flowering fertiliser

- PK boost in mid-flower

- Cal-Mag throughout

- Don't forget micronutrients