If you’ve wondered “What grow light is best for my indoor plants,” you’re in the right place. This guide breaks down what specs actually matter (lumens, wattage, PPF, CRI, full spectrum, etc.), how light science works, and how Soltech lights stack up for your plants and your space. By the end, you'll know exactly what features matter, and which Soltech grow light is the best match for your setup.
What to Look for When Buying Grow Lights: The Specs
New to grow lights? A good place to start is with our blog article breaking down what grow lights are and why you probably need them for your plants. If you’re already familiar with grow lights, let’s dive deeper into the specs and specifics!
Here are the technical terms that matter— what they mean, how they affect plants, and what good values look like. It’s simpler than it sounds.
|
Spec |
What It Measures |
Why It Matters for Plants |
|
PPF (Photosynthetic Photon Flux) |
Measures the total amount of usable light (photons) emitted by the light source per second over all directions. |
It’s how much light the plant can use for photosynthesis; more PPF → more potential growth (if other factors are good: duration, distance, etc.). |
|
PPFD (Photosynthetic Photon Flux Density) |
How many useful photons land on plant surfaces per square meter per second. Think: how much light is bathing your plant. |
If PPFD too low, plant is starved; too high, plant can burn or waste energy. Hanging height & beam angle matter. |
|
Wattage / Efficiency (Watts vs useful output) |
How much electrical power the light uses; efficiency is how much growth-usable light per watt. |
Higher efficiency means lower electric bill + less heat, more usable light. |
|
Lumens |
A measure of “how bright it looks to humans” — general brightness, weighted by visible spectrum. |
Useful for how pleasant / well-lit your room feels; less useful for plant growth alone (plants care about photons in red & blue, etc.). |
|
Color Temperature (Kelvin) |
How warm or cool the light appears (yellow/orange → warm; white → neutral; blue → cool). |
Warm & natural tones (around 3000K) tend to look more pleasant in homes; also, spectrum affects plant behavior (growth, flowering). |
|
CRI (Color Rendering Index) |
How accurately colors appear under the light compared to natural sunlight. |
High CRI means your plants (and everything around them) look “real” — leaves have richer color, less weird shadows/flooding. |
|
Lifespan / Warranty |
How long the LEDs last before dimming/losing quality; the warranty backing. |
Longer lifespan = more value; fewer replacements; better quality over time. |
What Do All These Grow Light Specs Actually Mean?
When you shop for grow lights, you’ll see a bunch of technical terms. Let’s break it down in terms of what it actually means when searching for high-quality grow lights that work for your plants:
PPF & PPFD
These measure how much “plant-usable” light is produced (PPF) and how much of it actually lands on your plant’s leaves (PPFD). A 2023 study in Frontiers in Plant Science found that plants grow best at a medium PPFD (around 300 μmol). Too much light didn’t help and plants became less efficient.
➡️ Translation: More isn’t always better.
💡 A Note from Soltech’s Engineers: Most light companies don’t show you exactly how effective their products are, however, we're happy to give you our direct data. We do this by contracting with U.L. Labs, a third-party testing facility, who are able to perform tests that give us our unique conversion factor.
They do this by converting our light output in lumens (a general measure of brightness) along with our signature light spectrum (the individual sub color bands that make up our light) and they translate that into PPF (total usable light for plants) and PPFD (exactly how much of that usable light makes its way to the plant) measured in μmol/sec. Simply put, we can guarantee you’re not giving your plants too much or too little light — just the right amount, because we’ve tested it.
While it's true that there are lights out there that will give you more growing power per-watt of energy consumed; they tend to have an odd-looking color spectrum and look more like they belong in a lab than in your home. That is the secret to Soltech; we've done the work so you don't have to, and we guarantee that our products will be attractive, last a long time, and provide just the right amount of light where your plants need it.
Wattage
This is how much power the light uses. But wattage alone doesn’t tell you how good a light is. A less efficient light can use more watts but give less usable light. What matters is how efficiently those watts are turned into PPF (plant-usable light).
➡️ Translation: More wattage does not equal a better or more powerful light, it just means it requires more energy usage (and sometimes a higher electricity bill). It’s more important how the watts are converted into usable light (PPF & PPFD).
Lumens
Lumens measure how bright the light looks to you, not your plant. They’re useful for aesthetics but not the whole plant-growth story.
➡️ Translation: Lumens = visible brightness to humans, not plants.
Spectrum / Full Spectrum
“The visible light spectrum is the set of wavelengths of electromagnetic radiation that human eyes can detect—roughly from 400 to 700 nanometres—which corresponds to the colours red, orange, yellow, green, blue, indigo, and violet,” according to Encyclopedia Britannica.
For houseplants, having access to this full spectrum is key: blue light encourages leafy growth, red light supports flowering, and the rest of the colors help balance development. That’s why a good full spectrum grow light is the closest thing to giving your plants natural sunlight indoors.
Plants use all parts of the visible spectrum, not just red and blue. A Frontiers in Plant Science 2021 study found that even green light — often ignored in cheap grow lights — boosted photosynthesis when added to white or red/blue light.
Image: The visible spectrum of light and the wavelengths of each color. When combined, we perceive white, natural light, similar to sunlight (Encyclopedia Britannica).
➡️ Translation: Plants really do use the whole rainbow of light spectrum. Full-spectrum grow lights are best for plants, not just cheap purple LEDs.
CRI (Color Rendering Index)
According to Westinghouse Lighting, “The color rendering index (CRI) is measured as a number between 0 and 100. At zero (0), all colors look the same. A CRI of 100 shows the true colors of the object.”
CRI tells you how accurate colors look under a light and a CRI of 100 represents total color accuracy. While it doesn’t mean much for plant growth, it does make sure that your plants look vivid and color accurate, almost as if they were sitting in the sun.
It’s important to note that CRI is totally independent from color temperature. As experts at Westinghouse explain, “CRI is independent of color temperature. These are two different things. For example, a 5000K (daylight color temperature) fluorescent light source could have a CRI of 75, but another 5000K fluorescent light source can have a CRI of 90.”
Image: A visual representation of how Color Rendering Index impacts the difference in how the color of apples look to the human eye at different CRI.
➡️ Translation: With high CRI, the lighting in your space feels natural, elevated, and your plants look beautiful. Soltech lights range between 97-98 CRI, rendering colors accurately, as if they’re in natural sunlight.
Color Temperature (Kelvin)
This is how “warm” or “cool” the light looks. Soltech uses 3000K warm white, which mimics a natural ambiance and makes your space feel warm and cozy.
Image: Different color temperatures and the equivalent types of light as a reference. (Seattle City’s Lighting Design Lab)
➡️ Translation: Lower Kelvin = warmer light, cozy-feel. Higher Kelvin = cooler light, sterile feel.
Lifespan / Warranty
LEDs are are longer lasting than other types of bulbs (and typically more energy efficient too!) meaning that you save time and money by not having to routinely replace burnt-out lights.
➡️ Translation: Long-lasting LEDs (like Soltech’s 50,000-hour rated lights), save money and hassle.
Putting Specs into Practice: What’s Best for Different Plant Needs
Image: A Soltech Aspect Gen 2 Pendant Grow Light is perfect for lighting plants on a bedside table, washing plants in a warm white glow and elevating your bedroom decor.
No “one size fits all” — depends on what type of plant(s) you have, how much natural light comes in, and how much space/design you want in your lighting.
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Low light / shade plants (e.g. ferns, peace lilies) → Lower PPFD needed; more forgiving. A light like the Vita bulb or Grove bar light is often sufficient. For example, the Vita offers ~ 25.95 µmol/sec PPF, 20 W, warm 3000K with high CRI (98).
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Medium light plants (many tropicals, most foliage plants) → Aim for higher PPF, you might hang lights closer or use a track system. The Highland Track System with ~ 40 µmol/sec and 30 W gives both flexibility and sufficient light.
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High light/flowering/succulents → Needs high PPFD, proper beam angle, possibly multiple lights; efficient wattage helps. The Aspect Gen 2 can handle plants with higher demand with dimming, over 110% more usable light than older Aspect versions.
Also, consider beam angle: narrower beams concentrate light (better for plants further away or needing intense light), wide beams spread light more evenly (good for tabletop clusters, closer distances). Soltech products often let you choose beam angles (e.g. Vita wide vs narrow; Highland narrow or wide).
Why Soltech Lights Hit a Sweet Spot: Specs + Design
Here’s where Soltech stands out — not just good numbers, but smart design + aesthetic.
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Full spectrum / warm-white glow: Soltech lights mimic natural sunlight at ~3000K, which means plants get red/blue/green wavelengths they need, and your room looks “normal” (not weird purple grow-light glow).
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High CRI (~97-98) so foliage, colors, textures in your room look rich and accurate. Good light isn’t just for the plants, also for you living with them.
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Dimming / adjustable: Soltech lights let you adjust output (~10-100%) so you can dial it back if the plant is getting too much, or give more when needed. Also lets you tone down light for ambiance, like when you’re having a cozy night in your home.
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Long lifespan + warranty: Many Soltech products are rated for ~ 50,000 hours (that’s ~10+ years at 12 hrs/day). Also backed by 3-5 year warranties. Our grow lights are built to last, so you’re not replacing lights all the time.
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Design & placement: The Aspect Gen 2 pendant style, Grove bar light, Vita bulb, or Highland track light system— each has aesthetic consideration. For example, the Aspect Gen 2 has optics that direct light where plants need it and reduce glare. Good for spaces where people spend time (living room, kitchen) so light isn’t harsh on eyes.
Why Full-Spectrum, High-CRI Lights Are Best for Plants and People
A 2023 study published in MDPI Buildings compared how indoor plants grew under natural sunlight versus fluorescent lighting. The researchers found that plants in sunlight developed healthier leaves and stronger photosynthesis than those under artificial fluorescent bulbs.
Or as the authors put it: “Plants exposed to natural light showed higher chlorophyll content and photosynthetic rates compared to those grown under fluorescent lighting.” Put simply, the closer an artificial light gets to mimicking the sun, the happier and healthier your plants will be.
That’s why Soltech lights are designed as full-spectrum, high-CRI, warm white lights. They mimic natural sunlight so your plants get what they need, and your living space looks beautifully lit instead of washed in purple or harsh hues.
Common Mistakes & What To Avoid When Choosing a Grow Light
To make your grow light actually work (not just look pretty):
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Choosing too much light for a plant that prefers dim light: burnt edges, or wrinkled leaves.
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Hanging the light too far: PPFD drops off fast. Use the hanging-height guides provided in the Grow Guide for each grow light.
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Ignoring spectrum & beam: cheap LED bulbs might not give the right red/blue light or spread; might be efficient (watts) but bad PPF or wrong beam angle.
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Not considering duration: even high PPF won’t help if the plant doesn’t get enough hours. Typically your grow light should be on for 10-14 hours/day depending on species & natural light.
Spec Highlights: Soltech Models & What They Do Best
You can always check our Compare Page to see models side-by-side, but here are a few Soltech models with different spec profiles as an overview:
Image: The Versa Tabletop Grow Light, styled on a bed frame provides full-spectrum lighting to plants while looking good doing it. Photo by @phillyfoliage.
Which Grow Light Is Right for You
Here are questions to ask yourself so you know what kind of grow light you should look for:
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How much natural light does your plant already get? If windows bring in strong sunlight, you might need less artificial light; dimmable lights help you fine-tune.
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What type of plants are you growing? Low-light foliage vs flowering vs succulents all have different light intensity & spectrum demands.
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How far is your plant from where you can mount or place a light? Distance affects PPFD a lot. Choose beam angle & mounting height accordingly for the Vita and Aspect Gen 2 grow lights.
💡 Pro Tip: Don’t want to mount a light or simply can’t (renters— we want you to get your security deposit back!), explore our tabletop solutions (Versa Table Top Grow Light) and grow light stands (Aspect Gen 2 X Stello Pendant Stand Set).
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How much space/style matter to you? If light is visible, you’ll want aesthetics (low glare, warm white, elegant design). Pendant style lights like Aspect, the design of cord, beam, etc, matter.
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Energy use & lifespan: Higher efficiency / longer lifespan lights save money + hassle long term.
Check out our Lighting Quiz and Plant Guide (80+ common houseplants) to match your plants’ needs to the perfect light.
How to Choose A Grow Light in 3 Easy Steps
Here’s a simplified process you can follow:
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Know your plant’s needs → Check if it’s low, medium, or high-light. Reference our Plant Guide to find all the details of your plant’s care!
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Check your space → How much natural light do you get? How far will the light hang above the plant? Think about your plant set-up and where your grow light will go.
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Pick your style → Do you want a pendant, a bar, or a bulb in your favorite lamp? Or would you prefer a ceiling mounted track system or a freestanding grow light to blend functional lighting with everyday living style lighting? With Soltech, you can match plant health to design, thinking about the aesthetic you’d like to achieve.
Want help finding your perfect grow light? Take our Lighting Quiz to match the right Soltech light to your space and plants. Or dive into our Plant Guide to see what grow lights are best for your favorite plants.
Grow lights are more than just a tool — with the right one, your plants thrive and your space feels beautiful.
