Environment
Intermediate
Lighting: HID, LED, and CMH — Choosing the Right Light
Light is the engine of cannabis growth. Understanding the difference between lighting technologies — intensity, spectrum, efficiency, and cost — is central to building an effective grow.
HID LIGHTING (High-Intensity Discharge)
HPS (High-Pressure Sodium) and MH (Metal Halide) have been the standard of professional cannabis cultivation for decades. HPS lights emit a yellow-orange spectrum ideal for flowering; MH emit a blue-white spectrum suited to vegetative growth. Many growers use MH for veg and switch to HPS for flower, or use dual-spectrum HPS (which contains both) throughout.
Advantages: lower purchase cost than equivalent LED; extremely well-documented performance in cannabis cultivation; replacement bulbs are cheap and widely available. Disadvantages: significant heat output requiring active cooling; shorter bulb lifespan (typically 10,000–15,000 hours versus 50,000+ for LED); higher electricity consumption for equivalent output.
A 600W HPS is the traditional standard for a 120 × 120 cm tent, delivering approximately 800–1,000 μmol/m²/s of PPFD at canopy level.
LED LIGHTING
Modern quantum board and chip-on-board (COB) LED technology has largely supplanted HID for home growers. High-quality LED panels from brands such as HLG (Horticulture Lighting Group), Spider Farmer, Mars Hydro, and others deliver full-spectrum light (including the red wavelengths critical for flowering) at significantly higher efficiency than HPS — typically 2.0–2.8 μmol/J versus 1.6–1.9 μmol/J for modern HPS.
The practical implications: an equivalent LED light produces the same or greater PPFD as an HPS while consuming 30–40% less electricity and generating significantly less heat. For a 120 × 120 cm tent, a 400–450W LED quantum board is broadly equivalent to a 600W HPS setup, running cooler and cheaper.
Initial purchase cost is higher than HID, but the lifespan advantage (50,000+ hours) and electricity savings typically produce net savings within 12–18 months for active growers.
CMH / LEC LIGHTING
Ceramic Metal Halide (CMH) — also called Light Emitting Ceramic (LEC) — occupies a middle ground. CMH bulbs produce a broad, natural-looking spectrum with excellent UV output (which may increase terpene and resin production), and their colour rendering index is higher than HPS. A 315W CMH is broadly equivalent to a 400W HPS in flowering performance while running cooler and producing a more complete spectrum.
CMH is particularly valued for the final weeks of flowering when terpene and cannabinoid production is highest, and some cultivators run CMH specifically for this phase.