Space & Environment: Choosing Between HPS and LED for Your Grow Area
Your growing environment and available space play crucial roles in determining whether HPS or LED lighting is the better choice for your setup. This guide helps you evaluate your specific situation to make the optimal lighting decision.
Space Considerations
Vertical Space Requirements
The height of your grow area can significantly impact your lighting choice:
| Light Type | Minimum Distance from Canopy | Implications |
|---|---|---|
| HPS (Open Reflector) | 18-24 inches | Requires more vertical space |
| HPS (Air Cooled) | 12-18 inches | Moderate vertical requirements |
| LED (Panel/Board) | 12-18 inches | Moderate vertical requirements |
| LED (Quantum Board) | 18-24 inches | Requires more vertical space |
In grow tents with limited height (5' or less), the space saved by using LEDs can be significant, allowing more room for plant growth.
Grow Area Dimensions
The footprint of your grow area affects light coverage and uniformity:
- Small Spaces (2×2 to 3×3): LEDs often provide more even coverage in small areas
- Medium Spaces (4×4): Both technologies work well with proper fixtures
- Large Spaces (5×5+): HPS excels at penetrating larger, denser canopies
Small Space Warning
In a 4×4 tent or smaller, a 600W or 1000W HPS can create significant heat management challenges. Without robust ventilation, temperatures can quickly reach harmful levels for plants.
Environmental Management
Heat Considerations
Perhaps the most significant difference between the two technologies is heat output:
| Factor | HPS | LED |
|---|---|---|
| Heat Output | High (70% of energy as heat) | Low (30-40% of energy as heat) |
| Temperature Increase | 10-15°F above ambient | 3-5°F above ambient |
| Cooling Requirements | Significant (extraction fans, possibly AC) | Minimal (basic ventilation) |
| Winter Benefit | Can reduce heating costs | May require supplemental heating |
"UK here too. Been MH/HPS for 20+ years now. I've been contemplating LEDs as they are improving all the time but I'm old and stuck in my ways! My main issue is heat, too hot in summer but that heat comes in really handy in winter."
Seasonal Considerations
Many growers adapt their lighting strategy seasonally:
- Summer: LED advantages become more pronounced as ambient temperatures rise
- Winter: HPS heat can be beneficial in colder environments, potentially offsetting heating costs
"HPS in the winter and led any other time"
Humidity Management
The different heat profiles of HPS and LED affect humidity management:
- HPS: Tends to lower relative humidity due to higher heat
- LED: May require dehumidification in sealed environments
Special Growing Techniques
Vertical Growing
For vertical growing setups, bare HPS bulbs can be particularly effective:
"For taller plants it's efficient to hang the bare bulb vertically and surround the bulb with plants (no reflector)."
Sea of Green (SOG)
For SOG setups with many smaller plants:
- LED: Often preferred due to more even light distribution across many plants
- HPS: Can work well but may create "hot spots" in the center of the canopy
Screen of Green (SCROG)
For SCROG setups with trained, even canopies:
- HPS: Excellent penetration through the even canopy
- LED: Works well with proper fixture selection and positioning
Decision Matrix: Which Light for Which Space?
LED is likely better if:
- Your grow space is 4×4 or smaller with limited height
- You have limited ventilation capabilities
- You grow primarily during summer months
- Your grow space is in a living area where heat/noise is a concern
- You need to minimize electricity usage
HPS is likely better if:
- Your grow space is 5×5 or larger with good height
- You have robust ventilation/cooling capabilities
- You grow primarily during winter months in a cold climate
- You're growing in a dedicated space where heat/noise isn't an issue
- You're on a tight initial budget
Hybrid Approaches for Challenging Spaces
Some growers with challenging environments opt for hybrid approaches:
- Seasonal Switching: LED in summer, HPS in winter
- Mixed Lighting: Combining both technologies in the same space
- Supplemental Lighting: Using one technology as the main light source and the other for targeted supplementation
These approaches can provide flexibility in managing your growing environment throughout the year.
The Bottom Line
Your growing environment should be the primary factor in your lighting decision. While both technologies can work in most spaces with proper management, one will typically be better suited to your specific situation.
Remember that environmental management is just as important as the lighting technology itself. The best light for your space is the one that allows you to maintain optimal growing conditions consistently throughout your growing cycle.