Full Spectrum vs Blurple LED Grow Lights: Which is Better?
Last updated: December 30, 2026 | 12 min read
Quick Answer
Full spectrum (white) LEDs are better than blurple lights in virtually every way. They're 30-50% more efficient, produce better yields, run cooler, and let you actually see your plants' true colors for health inspection. Blurple technology is from 2015-2018 and is now outdated. If you're buying new lights or replacing old ones, always choose full spectrum.
Table of Contents
If you've been growing indoors for a few years, you probably remember when purple-pink "blurple" LED grow lights dominated the market. Amazon was flooded with them. They promised to "give plants exactly what they need" by only providing red and blue wavelengths.
Fast forward to 2026, and the grow light landscape has completely changed. Visit any serious grow forum, and you'll see full spectrum white LEDs everywhere. The purple lights? They're mostly collecting dust in basements or being sold cheap on marketplace apps.
So what happened? And more importantly, if you're still using blurple lights or considering buying one because they're cheap, should you?
Let's break down the science, compare real-world performance, and help you make the right decision for your grow space.
What is a Blurple Grow Light?
"Blurple" is a portmanteau of "blue" and "purple" - describing the characteristic color these lights emit. They combine:
- Blue LEDs (440-460nm) - For vegetative growth and compact structure
- Red LEDs (630-660nm) - For flowering and fruit development
- Sometimes IR (infrared) and UV diodes in small amounts
The theory behind blurple lights made sense at the time: plants primarily absorb red and blue light for photosynthesis. Green light, the reasoning went, is mostly reflected (that's why plants look green). So why waste energy producing wavelengths plants don't use?
Popular blurple brands from 2015-2018: VIPARSPECTRA (older models), Roleadro, King Plus, Galaxyhydro, BESTVA (older models)
The Problem with Blurple Logic
The "only red and blue" theory turned out to be overly simplified. Research from Utah State University, Michigan State, and NASA has since shown:
- Plants DO use green light - Green wavelengths penetrate deeper into the canopy and reach lower leaves
- Full spectrum improves morphology - Plants grown under red/blue only can develop abnormally
- The efficiency argument was wrong - Modern white LED diodes are MORE efficient than old red/blue diodes
What is a Full Spectrum Grow Light?
Full spectrum LED grow lights emit white light that includes all wavelengths across the photosynthetically active radiation (PAR) spectrum (400-700nm). They look similar to natural sunlight - either a warm white, neutral white, or cool white depending on the exact diode mix.
Most modern full spectrum LEDs use Samsung LM301B or LM301H diodes, which are among the most efficient LEDs ever made for grow light applications (up to 3.1 umol/J efficiency).
Full Spectrum Light Composition (Typical)
Many full spectrum lights also add supplemental deep red (660nm) and infrared (730nm) diodes for enhanced flowering response.
The Science: Why Full Spectrum Wins
1. The McCree Curve: Not Just Red and Blue
In the 1970s, researcher Keith McCree measured how efficiently plants convert different wavelengths of light into photosynthesis. His findings created the famous "McCree Curve" - and it shows plants use ALL visible wavelengths, not just red and blue.
Key finding: Green light (500-600nm) is about 80-90% as efficient as red light for photosynthesis - NOT zero as blurple manufacturers claimed.
2. Canopy Penetration
One advantage green light has over red and blue: it penetrates deeper into the plant canopy. While red and blue light are absorbed by the top leaves, green light passes through and reaches lower leaves that would otherwise be shaded.
This means full spectrum lights provide more uniform lighting throughout the entire plant, improving overall yield - especially for dense, bushy plants.
3. LED Efficiency Revolution
When blurple lights were popular, the efficiency argument had some merit. Old red and blue LEDs were more efficient than old white LEDs.
But LED technology advanced rapidly:
| LED Type | Era | Efficiency (umol/J) |
|---|---|---|
| Old Blurple (generic red/blue) | 2014-2017 | 1.2-1.5 |
| Better Blurple (Epistar/Cree) | 2016-2018 | 1.7-2.0 |
| Samsung LM301B (full spectrum) | 2018-2022 | 2.5-2.8 |
| Samsung LM301H (full spectrum) | 2022-2026 | 2.8-3.1 |
Bottom line: Modern full spectrum LEDs produce 60-100% more usable light per watt than old blurple lights. You get better growth while paying less for electricity.
Head-to-Head Comparison: Full Spectrum vs Blurple
| Factor | Blurple | Full Spectrum | Winner |
|---|---|---|---|
| Efficiency (umol/J) | 1.2-2.0 | 2.5-3.1 | Full Spectrum |
| Electricity Cost | Higher | Lower (30-50% less) | Full Spectrum |
| Heat Output | Higher (more waste heat) | Lower | Full Spectrum |
| Plant Inspection | Difficult (purple tint) | Easy (natural colors) | Full Spectrum |
| Eye Safety/Comfort | Harsh on eyes | More comfortable | Full Spectrum |
| Yield (gram/watt) | 0.5-0.8 g/W typical | 1.0-1.5 g/W achievable | Full Spectrum |
| Lifespan | 25,000-35,000 hrs | 50,000-100,000 hrs | Full Spectrum |
| Upfront Cost | Lower ($50-150) | Higher ($100-400) | Blurple |
| Total Cost of Ownership | Higher (electricity + replacement) | Lower over 2+ years | Full Spectrum |
Summary: Full spectrum wins 8 out of 9 categories. The only advantage blurple has is lower upfront cost - but even this is negated by higher electricity bills over time.
When Blurple Lights Might Still Work
While we recommend full spectrum for most growers, there are a few scenarios where using existing blurple lights still makes sense:
1. You already own them and just need to grow something quickly
Blurple lights work. Plants will grow. If you have them sitting around and need to grow some seedlings or herbs, use what you have rather than buying new.
2. Supplemental flowering light
Some growers add blurple lights during flowering for extra red wavelengths alongside their main full spectrum lights. This is advanced optimization and not necessary for most grows.
3. Very small grows with no expansion plans
If you're growing a single houseplant or a few herbs and have zero budget, a $30 blurple from Amazon will work. Just know you're accepting significant efficiency losses.
Important: Never buy a NEW blurple light in 2026. Budget full spectrum options like the Spider Farmer SF-300 ($40) or Mars Hydro TS-600 ($60) are now so affordable there's no reason to buy outdated technology.
Should You Upgrade from Blurple to Full Spectrum?
Ask yourself these questions:
Is your blurple light more than 2-3 years old? Yes? LED diodes degrade over time, and your light is likely already 20-30% dimmer than when new.
Are you paying high electricity bills? Yes? Full spectrum LEDs can cut your grow room electricity cost by 30-50%.
Are you struggling to diagnose plant problems? Yes? Inspecting plants under purple light makes it nearly impossible to spot nutrient deficiencies, pests, or diseases early.
Do you want better yields? Yes? Full spectrum lights typically improve yields 20-40% compared to blurple lights with the same wattage draw.
Upgrade ROI Calculator
A 200W blurple light running 18 hours/day for 6 months costs about $78 in electricity (at $0.12/kWh). A 150W full spectrum light producing the SAME amount of usable light costs about $52.
Savings: $26 per 6 months, or $52/year. A $150 full spectrum light pays for itself in under 3 years through electricity savings alone - not counting improved yields.
Use our Grow Light Calculator to estimate your specific electricity savings.
Best Full Spectrum LED Grow Lights in 2026
If you're upgrading from blurple or buying your first quality light, here are our top recommendations by budget:
Budget Options (Under $100)
Spider Farmer SF-300
Best for Small Spaces33W actual draw | Samsung LM301 diodes | 2.5'x2' coverage | $39
Perfect for seedlings, clones, or small herb gardens. Incredible efficiency for the price. Ideal replacement for cheap Amazon blurple panels.
Check Price on AmazonMars Hydro TS-600
Best Value100W actual draw | 2'x2' coverage | $59
The go-to recommendation for first-time growers. Solid performance, great price, reflective hood design. Replaces a typical 150-200W blurple panel.
Check Price on AmazonMid-Range Options ($100-250)
Spider Farmer SF-1000
Most Popular100W actual draw | Samsung LM301B | 2'x2' flower / 3'x3' veg | $109
The gold standard for small-medium grows. Excellent diode selection, dimmable, 5-year warranty. Perfect for a 2x2 or 2x4 tent.
Check Price on AmazonMars Hydro TSW-2000
Best for 3x3300W actual draw | 3'x3' flower coverage | $189
Excellent choice for 3x3 tents. Higher power output, dimmable 0-100%, upgraded heat dissipation. Great efficiency for the price.
Check Price on AmazonPremium Options ($250+)
Spider Farmer SF-4000
Best for 4x4450W actual draw | Samsung LM301B + MeanWell driver | 4'x4' flower | $399
Serious light for serious growers. This single light replaces 600-800W of old blurple panels while producing more usable light. MeanWell driver for reliability.
Check Price on AmazonHLG 350R
Premium Pick350W actual draw | Samsung LM301H | 4'x4' coverage | $549
Horticulture Lighting Group makes the highest-quality LED grow lights on the market. US-assembled, 3-year warranty, best-in-class efficiency. For growers who want the absolute best.
Check Price on AmazonNot Sure Which Size You Need?
Use our free calculator to determine the exact wattage and PPFD requirements for your grow space and plant type.
Calculate Your Light RequirementsFrequently Asked Questions
Are blurple grow lights bad?
Blurple lights aren't necessarily bad, but they're outdated technology from 2015-2018. They work for growing plants but are 30-50% less efficient than modern full spectrum LEDs. The purple light also makes it difficult to inspect plants for health issues, pests, or deficiencies.
Why do some LED grow lights look purple?
Purple (blurple) grow lights combine primarily red and blue LEDs, the two wavelengths plants use most for photosynthesis. The technology was popular in early LED grow lights because it theoretically only provided "useful" light. Modern research shows plants benefit from the full spectrum, and newer diodes are more efficient.
What is a full spectrum LED grow light?
Full spectrum LED grow lights emit white light similar to natural sunlight, typically using Samsung LM301 diodes or similar. They include all wavelengths from blue through red (400-700nm), plus some infrared and UV. The white appearance comes from combining many wavelengths, not just red and blue.
Should I upgrade from blurple to full spectrum?
Yes, upgrading is recommended if your blurple light is over 2-3 years old. Modern full spectrum LEDs use 30-50% less electricity for the same growth, run cooler, last longer, and make plant inspection easier. The upgrade typically pays for itself in 1-2 years through energy savings.
Can I mix blurple and full spectrum lights?
Yes, you can mix light types during a transition period. Some growers add blurple lights during flowering for extra red wavelengths. However, for most growers, running all full spectrum lights is simpler and more efficient.
Final Verdict: Full Spectrum is the Clear Winner
The debate between full spectrum and blurple LED grow lights is essentially settled. Full spectrum wins on:
- Efficiency: 30-50% more light output per watt
- Yields: Better growth and higher production
- Plant health: Full spectrum encourages normal development
- Usability: See your plants' true colors for diagnosis
- Longevity: Modern LEDs last 50,000-100,000 hours
- Total cost: Lower electricity bills pay for the upgrade
The only scenario where blurple makes sense is if you already own one and need to grow something immediately with zero budget for upgrades. For anyone buying new, full spectrum is the only sensible choice in 2026.
Ready to Upgrade?
Use our calculator to find the perfect full spectrum light for your grow space, then check out our product recommendations above.
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