Understanding the PPFD (Photosynthetic Photon Flux Density) output of a grow light is critical for successful indoor cultivation. For the RX-PAR38-60D from Koray Lighting, growers often ask about its performance at typical hanging distances. Here’s a detailed breakdown.

Koray Lighting RX-PAR38-60D PPFD performance testing

What is the RX-PAR38-60D?

The RX-PAR38-60D is part of Koray Lighting’s RX-PAR38 series, where:

  • RX-PAR38: Indicates the PAR38 form factor (38mm diameter body)
  • 60D: Denotes the 60-degree beam angle, optimized for balance between intensity and coverage

This model is available in multiple wattage options (30W, 40W, 50W, 60W), each delivering different PPFD levels. The 60° beam angle concentrates light more effectively than wider angles (90° or 120°), resulting in higher PPFD at the center of the coverage area.

PPFD Performance at 0.3 Meters

At a hanging distance of 0.3 meters (12 inches), the RX-PAR38-60D delivers the following PPFD values:

  • RX-PAR38-30W-60D: 800-850 μmol/m²/s (center), 400-500 μmol/m²/s (edge of coverage)
  • RX-PAR38-40W-60D: 900-950 μmol/m²/s (center), 500-600 μmol/m²/s (edge)
  • RX-PAR38-50W-60D: 950-1000 μmol/m²/s (center), 600-700 μmol/m²/s (edge)
  • RX-PAR38-60W-60D: 1000-1100 μmol/m²/s (center), 700-800 μmol/m²/s (edge)

These values represent peak PPFD at the center of the light beam. The average PPFD across the entire coverage area is typically 60-70% of the peak value, depending on the reflectivity of the growing environment.

Koray Lighting PPFD measurement and testing equipment

Coverage Area at 0.3m Height

At 0.3 meters, the 60° beam angle creates a circular coverage pattern with a diameter of approximately 0.6-0.8 meters (24-32 inches). This coverage area is ideal for:

  • Single large plant (tomato, cannabis, pepper)
  • Multiple small plants (succulents, herbs, seedlings) clustered together
  • Compact grow tents (0.6×0.6m or 2’x2′)

The 60° beam angle provides deeper penetration into the plant canopy compared to wider angles, making it particularly effective for tall plants or those with dense foliage.

How Does This Compare to Other Beam Angles?

The beam angle significantly affects PPFD distribution:

  • 60° (RX-PAR38-60D): Highest center PPFD, smaller coverage area. Best for tall plants, flowering, and fruiting crops.
  • 90° (RX-PAR38-90D): Medium center PPFD (20-30% lower than 60°), larger coverage area (0.8-1.0m diameter). Good for mixed plant heights and general-purpose growing.
  • 120° (RX-PAR38-120D): Lowest center PPFD (40-50% lower than 60°), widest coverage (1.0-1.2m diameter). Ideal for low-canopy crops like lettuce, herbs, and seedlings.

PPFD Requirements for Different Plants

To put the RX-PAR38-60D’s output in context, here are typical PPFD requirements for various plant types:

  • Seedlings and cuttings: 100-300 μmol/m²/s
  • Leafy greens (lettuce, herbs): 200-400 μmol/m²/s
  • Vegetative growth (tomato, pepper): 400-600 μmol/m²/s
  • Flowering and fruiting: 600-1000+ μmol/m²/s
  • Medicinal plants (cannabis): 800-1500 μmol/m²/s (depending on stage)

With PPFD values reaching 1000+ μmol/m²/s at 0.3m, the RX-PAR38-60D (60W variant) can support all growth stages, including the demanding flowering phase.

Optimizing PPFD for Your Setup

To maximize the effectiveness of the RX-PAR38-60D:

  • Adjust hanging height: Moving the light closer (0.2m) increases PPFD by 30-40%, but be cautious of heat stress. Moving it higher (0.5m) decreases PPFD by 40-50% but increases coverage area.
  • Use reflective walls: Mylar or white reflective walls can increase average PPFD by 20-30% by redirecting lost light back to the plants.
  • Multiple fixtures: For larger areas, use multiple RX-PAR38-60D fixtures spaced 0.6-0.8m apart to ensure uniform coverage.
  • Dimming control: Use the compatible 0-10V dimmer to adjust PPFD levels for different growth stages or plant types.

Measuring PPFD in Your Setup

While Koray Lighting provides PPFD data from controlled testing, actual values in your setup may vary based on:

  • Ambient temperature (higher temps can reduce LED efficiency)
  • Voltage fluctuations
  • Reflectivity of surrounding surfaces
  • Age of the LED (light output decreases slightly over time)

For precise measurements, use a PAR meter or quantum sensor to map PPFD across your growing area. This helps identify hotspots or areas with insufficient light coverage.

The RX-PAR38-60D’s impressive PPFD output, combined with Koray’s secondary optics system for uniform distribution and no center hotspot, makes it a reliable choice for demanding indoor cultivation applications.

For detailed PPFD maps or to request test reports, contact Koray Lighting at www.koraylights.com.