LED (Light Emitting Diode)

LED (Light Emitting Diode) technology revolutionized indoor cannabis cultivation between 2015-2025, displacing HPS as the dominant indoor lighting standard. The technology: LEDs are semiconductor devices that emit light when electrical current passes through them; LED chips can be engineered to produce specific light wavelengths, allowing manufacturers to tune output spectrum precisely for plant photosynthesis. Modern full-spectrum cannabis LEDs combine multiple chip types: Royal blue (440-460nm) for vegetative compactness, Deep red (660-680nm) for flowering bud development, White (3000-5000K) for full-spectrum support, occasionally UV-A (385-400nm) and far-red (730nm) for terpene production and stretch control. Major LED categories by form factor: (1) Quantum boards — flat aluminum boards with hundreds of small LED chips (Samsung LM301, LM301H), efficient and even canopy coverage; brands include HLG, Spider Farmer, Mars Hydro. (2) Bar-style fixtures — multiple bars of LED chips spread across canopy area; popular for commercial wide-canopy operations; brands include Gavita, Fluence, ChilLED. (3) COB (chip-on-board) — older LED format with concentrated diodes on a single substrate; rapidly being replaced by quantum board efficiency. (4) Folding compact fixtures — for tent grows; portable and feature-rich. (5) UV/IR supplemental — small dedicated bars adding UV-A or far-red for terpene boost and stretch control. LED efficiency: measured in µmol/J (micromoles of photosynthetic photons per joule of electricity); modern commercial LEDs achieve 2.5-3.0 µmol/J vs 1.7-2.0 µmol/J for HPS; this means LEDs produce 30-50% more usable light per watt of electricity than HPS. Heat output: LEDs convert about 40% of electricity to light and 60% to heat (vs HPS at 30% light, 70% heat); this dramatically reduces cooling requirements but means lower-watt LEDs produce less canopy warmth, which can require supplemental heat in cool environments. Yield: properly tuned LED setups match or exceed HPS yields (1.0-1.5 g/watt achievable with skilled cultivation), with the lowered electricity costs making LED 30-50% cheaper per pound produced over the fixture lifetime. Trade-offs: LED upfront cost is 2-5x HPS cost, but 5-10 year fixture lifetime amortizes the difference; LEDs provide more uniform canopy coverage than HPS focal patterns; the dimmability of LED fixtures allows finer control over plant response.