Introduction to Hybrid Lighting
The hybrid lighting method—using both High-Pressure Sodium (HPS) and Light Emitting Diodes (LEDs)—is becoming the go-to approach for indoor cannabis cultivators looking to push yields and quality. But to truly master this system, you need more than just plugging in the lights—you need a Standard Operating Procedure (SOP).
1. Why Combine HPS and LED?
HPS delivers deep canopy penetration and high-intensity light, great for swelling buds. LEDs offer higher efficiency, lower heat, and better spectrum coverage. Combined, they:
Maximize photosynthetic efficiency
Provide fuller spectral coverage
Allow energy savings by reducing HPS runtime
Control heat output more flexibly
2. Basic Setup Overview
LEDs: Mounted evenly across the canopy for uniform coverage.
HPS: Placed between or alternating rows with LEDs for deep canopy penetration.
Ideal layout: 1 HPS fixture for every 2–3 LED bars (depending on wattage and room size)
3. Equipment You’ll Need
Full-spectrum LED lights (non-tunable is fine)
1000W DE HPS lights
Digital timer/controller
Environmental controller for HVAC and VPD
CO₂ injection system (optional but recommended)
Hygrometer and lux meter/PPFD meter
4. Understanding Cannabis Growth Stages
Veg Phase (Week 1–4+): Focus on lush foliage growth.
Transition/Pre-Flower (Week 1 Flower): Stretch and hormonal shift.
Bloom Phase (Week 2–8): Bud development and resin production.
Ripening (Final 1–2 Weeks): Finishing and fade.
5. Light Scheduling by Growth Stage
5.1 Veg Stage: LED Only (18/6 Schedule)
Use LEDs exclusively.
PPFD target: 300–600 µmol/m²/s
Maintain canopy temps 75–78°F with 65–70% RH.
5.2 Transition Week: Add Low HPS (18/6 or 12/12)
Turn on HPS at 30–50% capacity for heat acclimation.
PPFD target: 700–900 µmol/m²/s
Drop RH to 60–65%.
5.3 Bloom Phase: Full HPS + LED (12/12)
Run LEDs and HPS at full power.
PPFD target: 1000–1200 µmol/m²/s
Use CO₂ supplementation (800–1200 ppm recommended)
Canopy temps: 78–83°F (with CO₂), 74–78°F (without CO₂)
RH: 50–55%
6. PPFD & DLI Goals for Each Stage
| Stage | PPFD (µmol/m²/s) | DLI (mol/day) |
|---|---|---|
| Veg | 300–600 | 18–30 |
| Bloom | 900–1200 | 40–55 |
Use a PAR meter to dial this in accurately. Don’t guess.
7. Temperature Management (HVAC SOP)
7.1 HVAC Setup with Mixed Fixtures
Oversize your HVAC by 20–30% compared to LED-only setups.
Use active air-cooled HPS reflectors if possible.
Always vent HPS heat out of grow space.
7.2 Managing Heat from HPS
Run HPS during cooler night hours.
Set lights-on temp: 78–83°F with CO₂, 74–78°F without.
Lights-off temp: 65–70°F.
8. Humidity Control for Dual Lighting
HPS adds more IR, drying air faster.
Use humidifiers in early veg if RH drops below 60%.
Dehumidifiers are mandatory during bloom—aim for 45–50% RH final weeks.
9. Daily Light Management: Timers & Controls
Use programmable timers or smart controllers.
Set staged light-on routines:
LEDs first (10–15 min)
HPS second (after LEDs warm canopy)
Reverse order for lights-off.
10. CO₂ Strategy for High-PPFD Setups
Begin supplementation when PPFD > 800 µmol/m²/s.
Maintain 1000–1200 ppm during peak bloom for best results.
Turn off CO₂ during dark cycles.
11. Nutrient Adjustment with Hybrid Systems
Higher light intensity = higher metabolic demand.
Increase Cal-Mag slightly due to added stress from light + heat.
Monitor EC and adjust accordingly; more light = more uptake.
12. Common Mistakes to Avoid
Running HPS all day during veg (waste of energy & heat)
Poor HVAC leading to heat stress
Overwatering due to accelerated transpiration
Incorrect light hang heights causing bleaching
Conclusion
Mastering a hybrid lighting system isn’t just about flipping the switch on two types of lights—it’s about understanding when, how, and why to run each one. By following this SOP, indoor cannabis growers can dial in every parameter from veg to harvest, pushing quality, yield, and efficiency through the roof.