Introduction

What lights are best for growing microgreens? I don’t know…

I didn’t mean to trick you with that blog title, but the answer is super subjective.

I’ll try my best to outline the factors you should consider when buying grow lights for your microgreen farm. There are dozens of highly specific terms used by grow light manufacturers to explain why their lights are best. In reality, a lot of it is unimportant or unnecessary for the lights you need for microgreens. If you were building and operating a $10M cannabis farm, I’d encourage you to do a deep dive, but you’re not. Microgreens are simple plants, and lighting decisions can be simple if you let them be. I will briefly go over several definitions. After that, I will narrow the discussion to the key points - purchase price, operating cost, and light wavelength.

TLDR:

• Barrina T8 42W Pinkish White Lights ($80 for 4)
• Barrina T5 20W Full Spectrum Lights ($89 for 8)
• Hykolity T5 Full Spectrum Lights ($60 for 10)

Lighting Overview

Before you read the following definitions, let’s refresh our memory on photons. A photon is the most basic particle of light. It is the smallest possible packet of electromagnetic energy. Photons are what plants use to photosynthesize, but not all photons are created equal. A photon has no mass, moves at the speed of light, and carries energy that depends on its wavelength. The visible spectrum includes light with wavelengths between ~380nm and 740nm. The graph shows that many other spectrums exist beyond what we can see. These unseen spectrums affect our daily lives in many ways. Shorter wavelengths, like blue, carry more energy than longer wavelengths, like red.

Term	Abbr.	Definition
Photosynthetically Active Radiation	PAR	The range of light wavelengths (400–700 nm) that plants use for photosynthesis. It's not a measurement, but a range of light spectrums.
Photosynthetic Photon Flux	PPF	The total number of photosynthetically active photons emitted by a light source per second. It’s recorded in units of μmol/s. Think of it as the amount of usable light coming out of the fixture.
Photosynthetic Photon Flux Density	PPFD	The number of PAR photons landing on a square meter per second. It’s recorded in units of μmol/m²/s. This is what plants actually receive.
Daily Light Integral	DLI	The total amount of PAR light a plant receives in a day. It’s recorded in units of mol/m²/day. For example, microgreens prefer a DLI of 12-18.
Photon Efficiency	—	The PPF per watt of electrical power. Often shown in μmol/J. A higher photon efficiency means more usable photons per watt of electricity.
Color Temperature	CCT	Measured in Kelvin (K), this tells you how “warm” or “cool” a light looks. For example, 3000K looks warm and 6500K looks blue or cool. Less relevant for plants than PAR/PPFD.
Spectrum	—	Refers to the specific wavelengths of light a fixture emits. Full-spectrum lights mimic sunlight; red and blue-heavy spectrums are often used for grow-specific phases.
Red:Blue Ratio	—	The proportion of red (600–700 nm) to blue (400–500 nm) light. Studies show that higher blue ratios create more compact growth. Similarly, higher red ratios are better at creating biomass and inducing flowering.
Far-Red Light	—	Light in the 700–750 nm range. Helps influence photoperiodism and stretching.
Light Uniformity	—	Describes how evenly light is spread across the canopy. High uniformity creates consistent growth.
Light Intensity	—	A general term often used interchangeably, and sometimes incorrectly, for PPFD or lux. For plants, PPFD is the relevant metric.
Heat Output	—	How much heat the light emits. Important for close-canopy setups like microgreens.
Driver	—	The component that regulates power to the LEDs. Quality drivers affect light lifespan and consistency.
Photoperiod	—	The length of time plants receive light each day. Photoperiod is often controlled by outlet timers. Most growers set a photoperiod of 12-20 hours/day.

Here are the key factors to think about when buying and installing lights.

• PPFD Target: ~150–300 μmol/m²/s
• DLI Target: ~12–18 mol/m²/day
• Full Spectrum or Red-Blue Balanced
• Uniform Intensity
• Low Heat Output - Prevents Wilting

Let’s Focus In

Let’s now focus on the few factors that overwhelmingly matter for a small indoor microgreen farm. We’ll talk about the purchase price for the light, the amount of energy it uses, and the wavelengths it emits. Purchase price and electricity use are easy to conceptualize. All else being equal, we want to spend less money buying our lights, and we want the lights to use less electricity when they’re running. We don’t want to simply minimize costs, though. We want to maximize plant growth. If we can get a tray of the same crop to grow 1 oz. heavier in the same 10-day period by using better lights, that’s a huge win. Higher yields generate more revenue.

• Purchase Price
  1. We want to minimize the purchase price while maximizing the benefits to the plants. Easy enough.
• Energy Usage
  1. We’ll focus on the wattage (W) of the lights to determine energy use, which is an ongoing expense for your farm. To the layman, higher wattage should mean more usable light for the plants, but that’s not always the case. Wattage is a measure of how much electricity the light uses. What you really want to know is how many PAR photons the light generates per watt of electricity. The table shows that both a cheap and a premium light use 200W of electricity. However, the premium light produces twice as many useful photons for plants. More PAR photons make for faster plant growth. The implied trade-off in this example is that the premium LED likely costs more.
• Light Spectrum
  1. Plants mostly use light in the 400-700nm range, but not in equal amounts. Here’s the simplest way to explain why. Most plants are green. They’re green because their photosynthetic systems don’t work well with green-wavelength light. As a result, the green wavelengths are reflected instead of absorbed. Light manufacturers take this into account by creating lights focused on the most valuable and efficient wavelengths - red and blue. Some lights have separate red and blue diodes, or “blurple” diodes. These “blurple” diodes emit both wavelengths. The basic idea is that by removing green and other less useful wavelengths, the user saves electricity. This means they won’t waste energy producing photons that aren’t as important for the plants. In reality, it’s not worth the consideration when you’re a small farm. What makes it worse is that red, blue, and blurple lights hurt to look at.

Light	Wattage	PPF	Efficacy (μmol/J)
Cheap LED	200W	250	1.25
Premium LED	200W	500	2.5

Summary

When you're just starting, select grow lights based on cost, wattage, and wavelength. Cost matters because you don't want to spend too much on your appliances. However, you want to spend enough to get high-quality, efficient grow lights. Higher wattage is generally associated with greater plant growth, but not always. More watts also mean more electrical consumption and higher energy bills. Focus on finding lights with the most plant-usable light (PAR) for each watt. Wavelength is a common source of confusion for beginners. Red, blue, and "blurple" lights were once favored for their efficiency. However, they can be harsh on the eyes and unpleasant to work around. They also aren't much better than full-spectrum lights for small setups. Focus on buying full-spectrum LEDs, which try to replicate sunlight. Full-spectrum lights work well at all growth stages and for all crops. They're also more pleasant to work around. If you haven't done so, read our other blog about electrical factors before you buy a lot of lights and scale up - Electrical Considerations in Your Microgreen Farm. Last but not least, here are three light recommendations, depending on your preferences. Barrina is a reputable brand enjoyed by many microgreen growers. The first option is better if you’re willing to spend more on a stronger light. The pink-ish white hue isn’t too harsh to work around. The second option is a low wattage option. Lastly, the third light is what I’ve used since the beginning. We now own 400+ and they grow microgreens just fine. They’re not “grow lights,” per say, but they’re cheap and they’ve worked well.

• Barrina T8 42W Pinkish White Lights ($80 for 4)
• Barrina T5 20W Full Spectrum Lights ($89 for 8)
• Hykolity T5 Full Spectrum Lights ($60 for 10)

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