HPS vs. LED Myths Debunked: What's Actually True in 2024
The 2024 Reality
Many of the myths in this article originated in the early LED era (2008-2015) when LED technology genuinely underperformed. Modern LEDs have resolved most historical limitations. While we'll debunk myths about both technologies, it's important to acknowledge that LED is now the recommended choice for most growers. This guide helps you separate outdated beliefs from current facts.
The debate between HPS and LED grow lights has generated many myths and misconceptions from both camps. Let's examine what's actually true, what's outdated, and what you should consider for your growing decisions.
Outdated Myths About LED (Now Resolved)
These criticisms were valid in the past but no longer apply to modern LED fixtures:
RESOLVED: "LEDs don't produce dense buds"
Past reality: Early LEDs (pre-2015) lacked intensity and proper spectrum, often producing airy, underdeveloped flowers.
2024 reality: Modern LEDs with Samsung LM301H/B diodes produce bud density matching or exceeding HPS. Commercial facilities worldwide now produce award-winning flowers under LED exclusively. The key is adequate wattage and quality fixtures.
RESOLVED: "LEDs don't penetrate the canopy"
Past reality: Low-power LED panels couldn't match HPS's canopy penetration.
2024 reality: Modern bar-style LEDs (600-800W) with proper optics provide excellent penetration. While HPS may still have a slight edge in very tall, dense canopies, the difference is minimal with quality LED fixtures.
RESOLVED: "A 300W LED replaces a 1000W HPS"
Past marketing: Exaggerated equivalency claims damaged LED credibility.
2024 reality: Reputable manufacturers now provide accurate specifications. A quality 600-730W LED realistically replaces a 1000W HPS. A 400-480W LED replaces a 600W HPS. Always check actual PPF/PPFD numbers, not marketing claims.
Myths About HPS That Are Actually True
Some criticisms of HPS are legitimate concerns you should consider:
TRUE: HPS is significantly less efficient than modern LED
HPS achieves 1.0-1.7 µmol/J efficiency. Modern LEDs achieve 2.5-3.0 µmol/J. This means LED produces 50-100% more usable light per watt of electricity. Over a year, this translates to £400-500+ in electricity savings.
TRUE: HPS heat is often a problem, not a feature
While HPS heat can benefit cold-climate winter grows, for most growers most of the time, it's a liability requiring additional cooling equipment and electricity. In a 4x4 tent during summer, HPS heat often becomes unmanageable without AC.
TRUE: HPS bulbs degrade and need frequent replacement
HPS bulbs lose 10-15% output after 5,000 hours and should be replaced every 10,000-12,000 hours (12-18 months). This adds £40-60 annually to operating costs. LED fixtures maintain 90%+ output for 50,000+ hours—the fixture will likely outlast your growing career.
Myths About HPS That Are False or Exaggerated
Some criticisms of HPS are overstated:
FALSE: "HPS is obsolete technology"
While LED is now superior for most applications, HPS remains a functional technology. Properly maintained HPS systems still produce excellent results. Many legacy commercial operations continue using HPS productively. It's not "obsolete"—just no longer the optimal choice for new installations.
FALSE: "HPS produces lower quality results"
HPS has produced championship-winning flowers for decades. Many experienced growers report exceptionally dense, resinous results under HPS. Quality depends more on the grower's skill than the light technology. HPS can absolutely produce top-tier results.
FALSE: "You must switch to LED immediately"
If your HPS equipment works and you're achieving good results, there's no emergency to switch. Continue using your HPS until it needs replacement, then upgrade to LED. The best time to switch is when your ballast or bulb fails—not arbitrarily.
What's Actually True for Both Technologies
TRUE: Both can produce excellent results
When properly implemented, both HPS and quality LED systems can produce outstanding yields and quality. Your skill as a grower matters more than your light choice.
TRUE: Switching technologies requires adjustment
When transitioning from HPS to LED, you'll need to adjust watering (typically less frequent), nutrient concentrations (often lower), and environmental parameters. Your first grow under new lighting may require some experimentation.
TRUE: Cheap lights = poor results (regardless of type)
A £50 Amazon "1000W LED" will perform worse than a quality £200 HPS kit. A £150 HPS kit will perform worse than a £400 quality LED. Price and quality correlate. Invest in reputable brands—Spider Farmer, HLG, Gavita, Mars Hydro for LED; Lumatek, Phantom for HPS.
The Bottom Line
Most myths about LED originated in the 2008-2015 era and no longer apply. Modern LED technology has genuinely surpassed HPS in efficiency, and reputable manufacturers now produce fixtures that match or exceed HPS in every performance category.
That said, HPS remains a functional technology that can still produce excellent results. If you're currently growing successfully with HPS, there's no need to panic-switch. But when it's time to invest in new equipment, LED is objectively the better choice for the vast majority of growers.