The Complete Guide to Microgreen Lighting

Over the last seven years, we've tested countless lighting setups for growing microgreens indoors—different bulbs, intensities, budgets, and fixture styles. Honestly, lighting is still one of our favorite things to experiment with because it has such a dramatic impact on how microgreens grow.

And here's what we've learned: lighting affects far more than just plant height. The right light influences even growth, stronger stems, better color, fuller cotyledons, and can even impact flavor and nutrient density.

Too little light? You get stretching and legginess. Too much light? You risk stress or bleaching. Balance is everything.

The Science Behind Microgreen Lighting

Before diving into specific products and setups, let's talk about what makes good lighting for microgreens.

Light Spectrum: Why Color Matters

Research published in peer-reviewed agricultural journals has shown that different wavelengths of light can influence both the physiology and morphology of plants, with significant effects on biomass accumulation.

Here's what different parts of the light spectrum do:

Blue Light (440-470nm):

• Promotes compact, leafy growth
• Increases chlorophyll production
• Enhances vitamin C, E, and K content
• Can intensify spicy flavors in varieties like broccoli and mustard
• Helps prevent excessive stretching

Red Light (640-680nm):

• Stimulates stem elongation and leaf expansion
• Increases production of antioxidants and phenolic compounds
• Can enhance sweetness in varieties like peas and sunflower
• Promotes overall biomass accumulation

Green Light (500-600nm):

• Penetrates deeper into plant canopy than red or blue
• Contributes to photosynthesis in lower leaves
• Studies show positive correlation with biomass when combined with red and blue

Full Spectrum / Daylight (5500-6500K):

• Mimics natural sunlight
• Provides balanced wavelengths for all growth stages
• Simplifies lighting decisions for beginners
• Our go-to recommendation for most growers

For microgreens specifically, research indicates that a higher proportion of red light (around 60-85%) combined with blue light (10-20%) and some green light (10-20%) produces maximum fresh biomass.

Why We Use 5500-6500K Daylight Spectrum Lights (And Why They're Great for Nutrition)

After testing everything from specialized grow lights to basic shop lights, we've consistently returned to standard LED shop lights in the 5500-6500K range. Here's why—backed by science:

Research on White/Full-Spectrum LEDs Shows:

Studies comparing white LEDs to monochromatic red and blue lights found that white light produced microgreens with:

• Higher carotenoid content including lutein, beta-carotene, and alpha-carotene (all important antioxidants and vitamin A precursors)
• Better protein and fat content - white light microgreens showed higher levels of these macronutrients
• More chlorophyll - both chlorophyll a and b were higher under white light
• Superior fresh weight and biomass - white light generally resulted in higher fresh weight compared to monochromatic lights

One comprehensive study on kale microgreens found that those grown under white LEDs had significantly higher levels of all major carotenoids compared to those grown under specialized red or blue LEDs. Link: https://www.mdpi.com/2076-3921/12/9/1686

Another multi-species study concluded that "white LEDs supported the best growth and had positive effects on most parameters across various species," making them ideal for growers producing multiple microgreen varieties.

The Practical Advantage:

While specialized grow lights with optimized red/blue ratios can increase specific compounds (like phenolics under blue light), white/daylight spectrum lights provide:

• Excellent all-around nutrition across the board
• Better visual assessment of plant health (true colors, not purple light)
• Lower cost and easier availability
• Simpler setup with proven results
• Strong performance across ALL microgreen varieties

This is exactly why our standard setup uses three 20-watt LED shop lights in the 5500-6500K range per shelf. The science supports what we've experienced: these simple, affordable lights produce nutritionally dense microgreens with excellent growth characteristics.

Light Intensity: How Much is Enough?

Light intensity is measured in several ways, but for plant growing, the most accurate measurement is PPFD (Photosynthetic Photon Flux Density), measured in µmol/m²/s. However, most consumer lights are rated in lumens or watts, which we'll discuss too.

Scientific studies on microgreens have found that light intensity significantly affects agronomic characteristics including fresh weight yield, dry weight yield, dry matter, hypocotyl length, and cotyledon area.

Research-backed intensity recommendations:

• Minimum: 100-120 µmol/m²/s for basic growth
• Optimal: 200-400 µmol/m²/s for best results
• Commercial: Up to 270 µmol/m²/s for maximum yields

In practical terms for home growers using standard LED shop lights, this translates to roughly 2,000+ lumens per shelf for a standard 10x20 tray setup.

Studies have demonstrated that microgreens grown under low light intensity (50 µmol/m²/s) had poorer yield and lower antioxidant activity compared to microgreens under high light intensity (200 µmol/m²/s).

Photoperiod: Light Duration Matters

Photoperiod refers to how long lights stay on each day. Most microgreens perform best with 12-16 hours of light daily.

Our testing has settled on 17 hours on, 7 hours off as our sweet spot. This gives microgreens plenty of time to photosynthesize without overstressing them.

Interestingly, research shows that a long photoperiod at low intensity is better than a short photoperiod at high light intensity in terms of energy and financial efficiency. However, for home growers, 16-17 hours at moderate intensity provides the best balance of growth and electricity costs.

Our Recommended Lighting Setups

Based on seven years of hands-on testing combined with current research, here are our lighting recommendations for different scenarios:

For Standard Grow Racks (Most Popular)

Our Setup:

• Three 20-watt LED shop lights per shelf
• Color temperature: 5500-6500K (daylight spectrum)
• Total output: ~2,000 lumens per shelf
• Positioned 6-12 inches above trays
• Timer set for 17 hours on, 7 hours off

This setup works perfectly for growing microgreens on reusable grow mediums, soil, or coco coir in standard 10x20 trays.

Why we like this setup:

• Affordable initial investment
• Energy efficient
• Easy to scale (add more shelves)
• Widely available
• Consistent, proven results
• Produces microgreens with excellent nutritional content (as shown in research)

Find our exact grow rack and lighting setup here.

T5 LED Lights (Beginner-Friendly)

T5 LED lights are one of the most beginner-friendly options for microgreens. These typically come in 20-watt configurations and provide moderate intensity that's easy to dial in.

Setup recommendations:

• Use 2-3 T5 lights per shelf
• Position 8-12 inches above trays
• Adjust height as microgreens grow

T5s provide enough light for healthy growth without overwhelming beginners with too many variables. The lower intensity also means more forgiveness with positioning—you won't burn microgreens as easily.

T8 LED Lights (Stronger Growth)

T8 LED lights are a step up from T5s, typically offering 40 watts per fixture. These can really improve color development and overall growth quality.

What we've noticed with T8s:

• Deeper, more vibrant colors in varieties like red cabbage and amaranth
• Thicker, sturdier stems
• Better cotyledon expansion
• Faster growth rates

Important note: T8s require more attention to distance. Too close and you risk light stress or bleaching. We recommend starting at 12 inches above trays and adjusting based on plant response.

Find T8 and other lights we've tested in our alternative lights collection.

Panel-Style Grow Lights (Advanced Option)

For growers wanting professional-grade results or growing crops beyond microgreens, panel-style LED grow lights like the Spider Farmer SF1000 (100W) offer excellent performance.

Benefits of panel lights:

• Higher PPFD output (typically 200-400+ µmol/m²/s)
• Full spectrum with optimized red/blue ratio
• Larger coverage area
• Dimmable controls
• Professional-grade results

Drawbacks:

• Higher upfront cost
• Overkill for microgreens alone
• May require dimming for optimal microgreen growth
• More heat output

We use panel lights primarily for our aeroponic systems and other indoor plants, but they absolutely work for microgreens when properly positioned and potentially dimmed.

How Light Affects Microgreen Quality

Beyond basic growth, lighting impacts several quality factors that matter to both growers and consumers.

Nutritional Content

Multiple studies have documented how lighting affects microgreen nutrition. Research shows that a 16-hour photoperiod increased phenolic compounds by 32%, total betalains by 49%, and antioxidant capacity by 25% compared to a 12-hour photoperiod.

Different light spectrums can enhance specific nutrients:

• Blue light increases vitamins C, E, and K
• Red light boosts antioxidants and phenolic compounds
• White/full-spectrum light increases carotenoids, chlorophyll, and overall balanced nutrition
• Higher intensity (within optimal range) increases overall nutrient density

Color Development

Light quality dramatically affects the visual appeal of microgreens. We've noticed:

• Reds and purples develop best under full-spectrum or red-heavy lights
• Deep greens come from adequate blue light and proper intensity
• Pale or yellow greens indicate insufficient light intensity
• Bleached appearance suggests too much light too close

Flavor Profiles

Yes, lighting even affects taste! Research has shown:

• Blue light can intensify spicy, peppery flavors in brassicas
• Red light can increase sugar production, creating sweeter profiles
• Proper intensity creates more concentrated flavors overall

Stem and Leaf Structure

Proper lighting creates the structural characteristics everyone wants:

• Strong, thick stems from balanced spectrum and adequate intensity
• Full cotyledons from sufficient light reaching all parts of the plant
• Compact, sturdy plants from appropriate blue light
• Even canopy from uniform light distribution

 

 

Common Lighting Mistakes (And How to Fix Them)

After seven years, we've made plenty of mistakes—and learned from them. Here are the most common issues:

Mistake #1: Lights Too Far Away

Signs:

• Leggy, stretched microgreens
• Pale color
• Thin stems
• Slow growth

Fix: Lower lights to 6-12 inches above the canopy. As a general rule, you should be able to hold your hand at plant level and feel slight warmth from the lights.

Mistake #2: Lights Too Close

Signs:

• Bleached or whitish leaves
• Stunted growth
• Crispy edges on cotyledons
• Plants leaning away from light

Fix: Raise lights to 10-15 inches and monitor. Remember that LEDs produce less heat than older technologies, but light intensity can still cause stress.

Mistake #3: Inconsistent Photoperiod

Signs:

• Irregular growth patterns
• Some trays developing faster than others
• Difficulty predicting harvest timing

Fix: Use a reliable timer. We use programmable timers set for 17 hours on, 7 hours off, every single day.

Mistake #4: Uneven Light Distribution

Signs:

• Microgreens growing toward one side
• Better growth under certain areas of the shelf
• Inconsistent color across trays

Fix: Use multiple light fixtures per shelf for even coverage. Our three-light setup per shelf eliminates this issue completely.

Mistake #5: Wrong Color Temperature

Signs:

• Acceptable growth but not optimal
• Colors seem "off"
• Growth slower than expected

Fix: Stick with 5500-6500K (daylight/cool white) for microgreens. Warm white (2700-3000K) doesn't provide the right spectrum for optimal growth.

Lighting by Growing Method

Different growing setups may need slightly adjusted lighting approaches:

Soil or Coco Coir Growing

When growing on soil or coco coir in trays, standard LED shop lights work perfectly. The growing medium provides good insulation, so you have more flexibility with light intensity.

Recommendations:

• 2-3 LED lights per shelf
• 8-12 inches above soil surface
• Start lights after seeds germinate and emerge

Reusable Grow Medium (Hydroponic)

Growing on reusable silicone or steel mesh requires the same lighting as soil, but watch for algae growth if lights are too close to wet surfaces.

Recommendations:

• Same intensity as soil growing
• Keep lights at least 8 inches from wet mesh to reduce algae
• Good airflow helps prevent algae even under bright lights

Kratky or Aeroponic Systems

For Kratky systems or aeroponic setups, you may want slightly higher intensity since these systems typically produce larger, more mature plants.

Recommendations:

• 3 LED lights minimum per shelf
• Consider T8 (40W) instead of T5 (20W)
• Or use panel lights for best results with larger plants

Budget-Friendly vs. Premium Options

Lighting doesn't have to break the bank, but investing more does give better results.

Budget Setup ($50-100 per shelf)

Start with 2-3 basic LED shop lights from hardware stores:

• Look for 20W fixtures
• Choose 5500-6500K color temperature
• Add a simple timer

This basic setup will grow perfectly good microgreens for home use.

Mid-Range Setup ($100-200 per shelf)

Upgrade to higher-quality fixtures:

• Quality T5 or T8 LED fixtures
• 3 lights per shelf for better coverage
• Programmable timer for precise control
• Complete grow rack system

This is what we use for most of our microgreen production—it's the sweet spot of cost and performance.

Premium Setup ($200-400+ per shelf)

For commercial growers or serious hobbyists:

• Panel-style grow lights with optimized spectrum
• Dimmable controls
• Higher PPFD output (250-400 µmol/m²/s)
• Advanced timers with sunrise/sunset simulation

Browse our collection of tested lights to find options at every budget level.

Energy Efficiency and Operating Costs

One major advantage of LED lighting is energy efficiency. Let's break down the costs:

Example: Standard 3-Light Shelf Setup

Specifications:

• Three 20W LED lights = 60W total
• Running 17 hours per day
• Average electricity cost: $0.12 per kWh

Monthly cost calculation:

• Daily usage: 60W × 17 hours = 1,020 watt-hours = 1.02 kWh
• Monthly usage: 1.02 kWh × 30 days = 30.6 kWh
• Monthly cost: 30.6 × $0.12 = $3.67 per shelf

Research on microgreen production has found that a long photoperiod at low intensity is more cost-effective than short photoperiods at high intensity, which supports our 17-hour schedule with moderate-wattage lights.

Comparing Light Types

LED Shop Lights (20-40W):

• Lowest operating cost
• Longest lifespan (50,000+ hours)
• Minimal heat output
• Winner for efficiency

Fluorescent (if still using):

• Higher energy use for same light output
• Shorter lifespan
• Contains mercury (disposal concerns)
• Being phased out

Panel Grow Lights (100W+):

• Higher operating cost
• Professional results
• Better for larger operations
• Worth it if growing at scale

Setting Up Your First Lighting System

Ready to get started? Here's our step-by-step process:

Step 1: Choose Your Rack

Start with a sturdy grow rack that can support lights and trays. We prefer metal shelving with adjustable heights.

Step 2: Select Your Lights

For beginners, we recommend starting with our proven 3-light setup using 20W LED shop lights in the 5500-6500K range.

Step 3: Install Lights

Mount lights to the underside of each shelf, positioning them so they'll sit 8-12 inches above your growing trays.

Step 4: Add a Timer

Connect all lights to a timer set for 17 hours on, 7 hours off. We prefer starting lights at 6 AM and shutting off at 11 PM, but adjust to your schedule.

Step 5: Test and Adjust

Grow your first batch and watch carefully:

• Are microgreens stretching? → Lower lights
• Seeing bleaching or stress? → Raise lights
• Slow growth? → Add more lights or decrease distance

Advanced Tips from 7 Years of Testing

Tip #1: Light Height Adjustment

As microgreens grow, the distance to light naturally decreases. We don't typically adjust light height during a grow cycle—the changing distance seems to benefit development.

Our approach:

• Set lights 10-12 inches above empty trays
• By harvest, microgreens are 6-8 inches from light
• This gradual intensity increase works well

Tip #2: Reflective Surfaces

Adding reflective material around your grow area (white walls, mylar, aluminum foil) can increase effective light by 10-30%. We simply keep our grow area walls painted bright white.

Tip #3: Clean Your Lights

Dust accumulation on lights can reduce output by 20% or more. Wipe lights down monthly to maintain full brightness.

Tip #4: Track Your Results

Keep notes on:

• Which lights you used
• Distance from plants
• Photoperiod length
• Microgreen variety
• Growth results

Over time, you'll dial in perfect settings for your space and favorite varieties.

Tip #5: Experiment Wisely

Try different setups, but change only one variable at a time. Testing new lights? Keep everything else the same. This way you know what's working.

Variety-Specific Lighting Notes

Through extensive testing, we've noticed some varieties respond differently to lighting:

Light-Hungry Varieties (need more intensity):

• Sunflower
• Pea shoots
• Cilantro
• Nasturtium

Standard Light Requirements:

• Broccoli
• Radish
• Kale
• Cabbage
• Mustard

Lower Light Tolerance (but still need adequate light):

• Beet greens
• Lettuce
• Mizuna

All varieties will grow under our standard 3-light setup, but fine-tuning for specific crops can improve results.

Troubleshooting Guide

Problem: Leggy, Stretched Microgreens

Possible causes:

• Insufficient light intensity
• Lights too far away
• Wrong spectrum (too warm/yellow)

Solutions:

• Add more lights or switch to higher wattage
• Lower lights to 6-8 inches
• Ensure lights are 5500-6500K

Problem: Pale or Yellow Microgreens

Possible causes:

• Not enough light
• Nutrient deficiency (if growing hydroponically)
• Lights not on long enough

Solutions:

• Increase intensity or decrease distance
• Check/add fertilizer if growing without soil
• Verify timer is working (should be 16-17 hours)

Problem: Uneven Growth

Possible causes:

• Uneven light distribution
• Single light source
• Crowded trays blocking light

Solutions:

• Use multiple lights per shelf (we use 3)
• Rotate trays halfway through growth
• Give trays adequate spacing

Problem: Bleached or Crispy Leaves

Possible causes:

• Lights too close
• Too much intensity
• Heat stress (rare with LEDs)

Solutions:

• Raise lights to 10-12 inches
• Reduce number of lights or switch to lower wattage
• Ensure adequate air circulation

There's No Single "Perfect" Light

Here's the truth we've learned after seven years: there's no one-size-fits-all perfect light for everyone.

Your ideal lighting setup depends on:

• Space size - Small countertop vs. full room
• Rack configuration - Shelf height and width
• Number of trays - Growing 2 or 20 at a time
• Budget - What you can invest upfront
• Goals - Home use vs. selling at market
• Varieties - What you're growing most often
• Electricity costs - Varies by location

This is why testing and adjusting over time matters so much. Lighting is one of the biggest levers you can pull to improve your grows.

Our Current Favorite Setup

After testing everything from basic shop lights to professional horticultural panels, here's what we've settled on for our main microgreen production:

Configuration:

• Three 20W LED shop lights per shelf
• 5500-6500K color temperature
• Mounted 10-12 inches above trays initially
• Timer set for 17 hours on, 7 hours off
• Growing on 10x20 trays
• Using reusable grow mediums, soil, or coco coir

Why this works for us:

• Affordable and scalable
• Consistent, reliable results
• Energy efficient
• Easy to replace parts
• Produces market-quality microgreens
• Research-backed nutritional benefits from white/full-spectrum light

Find our complete grow rack and lighting setup here.

Final Thoughts

Lighting can seem complicated at first, but it doesn't have to be. Start with a simple, proven setup—like our three-light configuration—and grow from there. Pay attention to how your microgreens respond, make small adjustments, and keep notes on what works.

The beauty of microgreens is their short growth cycle. If a lighting experiment doesn't work perfectly, you'll know in 7-14 days and can adjust for the next batch.

Remember: the "best" light is the one that fits your space, budget, and goals while producing microgreens you're proud of—and the science shows that simple daylight-spectrum LEDs deliver excellent nutrition along with great growth.

Want to see the exact lights we use and recommend? Check out our Amazon storefront lighting collection, or explore other lights we've tested. And if you are Looking for the Best Microgreen Growing Advice? Start with On The Grow

For trays, growing mediums, and other supplies, visit OnTheGrow.net.

And if you want comprehensive training on growing microgreens from start to finish—including advanced lighting techniques—check out our Microgreen Masterclass.

What lighting setup are you currently using? Have questions about upgrading or getting started? Drop them in the comments below—we love talking about lights!

Happy growing! 🌱

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SOURCES CITED:

This blog references peer-reviewed research including:

• Studies on white LED effects on carotenoid and chlorophyll content in kale microgreens (MDPI Antioxidants, 2023)
• Research comparing white, red, and blue LED effects on cabbage microgreen nutrition (MDPI Applied Sciences, 2023)
• Multi-species studies on light spectrum and biomass accumulation (MDPI Plants, 2024)
• Investigations into photoperiod effects on antioxidant content (MDPI Horticulturae, 2023)
• Cost-efficiency studies on spectrum and intensity ratios (E3S Conferences, 2023)
• Multiple agricultural science publications on controlled environment agriculture