led blue grow light

Blue LED Grow Lights: Best Fixtures For Seeding And Vegging?

Last updated June 19, 2020 By Steven 2 Comments

Let’s clear up a big misconception right away.

Blue LED grow lights are not the best choice for vegging.

Plants in the vegetative stage love blue light, that is true. But they don’t want only blue light.

They do much better if they are also getting light in every other color, especially red. They want: mostly blue, a good amount of red, and some of every other color.

So what are blue lights good for then?

Well, they do work for vegging. They’re just not ideal. The same goes for seeding.

Apart from the first light listed below, which includes some white diodes and thus has light in every color, blue LED panels and bulbs are best used as supplemental lighting.

That is their strength.

If you have a primary light that is mostly red, these blue fixtures are a great way to increase the blue light hitting your plants.

Red-heavy fixtures are often used for flowering. By providing some additional blue light during the vegging stage, you can give your plants better light for that stage, without having to get a whole new lighting fixture.

These blue LED fixtures are all extremely inexpensive, making them a nice, cheap way to boost plant growth.

But you do have to make sure you get a good one. Many of the options out there are completely useless. That’s why I’ve narrowed them down to the best few. I also included a more expensive full-spectrum light below, in case you are not looking for supplemental lighting, but a fixture that can veg on its own.

Let’s take a closer look at the lights.

Blue Spectrum LED Grow Lights: Comparison Table

Model Size Wattage Spectrum Output Rating Cost
HLG 300L BSpec
Check Price
9 lbs.

How Does Blue Light Affect Plant Growth?

Before we get to the individual reviews, I wanted to briefly explain what blue light does for plants. This post has a more in-depth explanation of the effect of different colors of light on plants.

Blue photons drive the photosynthetic reaction and blue light regulates the opening of stomata. Those are minuscule openings on that leaves that control water loss carbon dioxide intake.

The most important function for our purposes is that blue light suppresses extension growth. This results in shorter plants with thicker, bushier leaf growth. Without blue light, plants will stretch and grow spindly and weak.

Best Blue LED Grow Light: Review Of The Top 5

These are the top 5 blue spectrum LED grow lights currently available. I’ll begin with the best vegging light period (though it uses blue-heavy white light, not blue light), and then follow with the best blue bulbs and panels.

Best Blue LED For Vegging And Seedlings: HLG 300L V2 BSpec

This light has some blue LEDs for a vegging boost, but is mostly made up of full-spectrum white LEDs.

So why is it my favorite light for vegging and for seedlings?

Because white light is far better for plants than only blue light. White light contains all colors of the spectrum, just like sunlight. And that is what plants really want.

The HLG 300L V2 Bspec uses high quality Samsung LM301H diodes with a color temperature of 3500K. That is a warmish white light that will actually work for any stage of growth, but it contains a good amount of blue light, making it especially good for vegging.

The fixture also has 470 nm blue diodes to supplement the white light and really provide a vegging boost.

The one thing HLG lights are famous for is their efficiency. They give you a far greater output for the wattage input than other LED lights. This is largely due to the Samsung chips and Meanwell drivers, both of which are the industry standard.

The driver is also dimmable, from 90 to 270 watts. This means you can dial down the power when you don’t need the light to be as strong, which saves you money. If you are using it for seedlings, for example, you probably won’t need it on full power.

HLG lights give you are large, even coverage area due to the way they are configured, with many smaller diodes spread out over a large panel. This also means they can be cooled passively, so there is no need for a noisy fan to dissipate heat.

Horticulture Lighting Group provides a 3 year warranty on their lights and they are very good at follow up service, if you have any issues. Customer service is the area where they have made a ton of improvements over the past year and now rank among the top brands in that department.

  • Great spectrum with mix of 470 nm blue and 3,500K white diodes
  • Incredible efficiency of 2.5 umol/j (it is a 600w MH equivalent light while using only 270w)
  • Extremely high quality components
  • Most expensive light on this list by far (but it is a standalone fixture, while the others are really just supplemental lights)

Best Blue LED Grow Light Bulb: ABI True 24 Watt Blue LED Bulb

The 24 watt blue blue from ABI is the best blue LED grow light bulb on the market. It rates above the other good choice further down this page, because it is more powerful, though it may not seem like it at first glance. And also for honesty and quality.

This bulb is 24 watts and that one is 36 watts, so how is this one more powerful?

Because 24 watts is the actual power draw, while the other bulb below has an actual draw of 20 watts. In general, the 2 bulbs are very close, but I gave this one the edge in power and in being honest about that power.

Instead of calling their bulb a “45 watt” light, like most Chinese brands would, they call it a 24 watt light, because that is the actual power consumption. That kind of honesty should be rewarded, especially in an industry where it is exceedingly rare.

But honesty isn’t the only thing ABI has going for them. They also make a great little bulb.

It screws right into any standard light socket (E26), so you can use it in an existing lamp fixture you may already own. The diodes emit a blue light with a wavelength from 450 to 460 nm.

The reason this bulb is able to get more power than most competing bulbs is an integrated ball-bearing cooling fan. It runs quiet, but keeps the temperature down, which makes it possible to get more power into a bulb this size than usual.

The ABI bulb is assembled in the USA from quality components. It is rated for 50,000+ hours of use and comes with a 3-year manufacturer’s warranty.

  • Works in any standard light socket (E26)
  • High output for a LED bulb (with a 24 watt power draw)
  • Assembled in the US from high-quality components
  • 3 year warranty
  • ABI does not provide lumen or PPDF info

Thinnest Blue LED Light Panel: Yescom Blue Ultra-Thin LED Grow Light Panel

The Ultrathin 225 LED Panel from Yescom is the thinnest grow light I’ve ever seen, apart from strip lights. That makes it a great choice for supplemental light. I would not use it as a standalone fixture, though.

The main reason for that is the limited spectrum. As the only light source, you’d want some light in every color, not just blue. Even for seeding. For that reason, I recommend the first fixture listed above if you are looking for a standalone seeding light.

But if you’re looking to supplement an existing light with some additional blue light, this fixture will do just that. And its small size gives it some more flexibility than the first fixture on this list.

This light only draws 22 watts, but has a lumen output of 2475. That gives it more output than the first fixture, but this light has no lenses, so the light is not as focused and won’t penetrate as deeply into the canopy. That said, canopy penetration is not a strong point of any of these lights, nor is it something you’d expect in a supplemental light.

The 225 diodes on this panel emit a blue light with a wavelength of 450 nm. The panel has a rated lifespan of 50,000 hours. Yescom does not provide a warranty. The same fixture is also available with white diodes, instead of blue. Using the two in combination could be a great idea, depending on the kind of light your plants are already getting.

  • Great output for only 22 watt input
  • Ultra-thin and light weight
  • 50,000 hour rated lifespan
  • No warranty

Great Alternative LED Bulb: HiGrow 36 Watt Blue LED Grow Bulb

The ABI bulb reviewed above is my favorite, but this 36 watt blue bulb from HiGrow is a close second. My main issue with this bulb is the fact that it only draws 22 watts of power, not 36 as stated, and it is lower quality.

Obviously I know that every Chinese brand (and many US brands) follows this naming convention that is best referred to as “lying”, but ABI does not. I like that.

Either way, the ABI bulb is more powerful than this one, though they do not provide any actual output data, unfortunately.

HiGrow does provide some data, which states that their blue bulb gives you 1046 lumen of light. It uses 18 all-blue 2w Bridgelux/Epileds diodes with a wavelength of 450 to 460 nm. 90° lenses focus the light downward into a more intense beam.

Like the ABI bulb, this one also screws into any standard E26/E27 light socket. Unlike that bulb, this one does not have a fan, but uses 0603 aluminum heat sinks. They work well, but without the fan, this bulb can’t quite generate the same type of power as a fan would allow.

This bulb is made from lower quality components than the ABI bulb (plus it’s assembled in China), so you can expect a bit of a higher failure rate (i.e. your chances of getting a bad bulb are slightly higher), which is another big reason I prefer the ABI bulb. That said, HiGrow give do you a 1 year warranty and a 30 day money back guarantee.

  • Screws into any standard E26/E27 light socket
  • Rated lifespan of 50,000 hours
  • 1 year warranty and 30 day money back guarantee
  • Lower power than the ABI option
  • Lower quality components than the ABI bulb

Best Budget Blue LED: Miracle LED 100 Watt Starter Bulb

The Miracle LED Grow Lite Growth Starter bulb is a bit different from the other lights on this list. It looks exactly like a standard incandescent lightbulb.

Naturally, it screws into any standard socket (just like the two LED bulbs above). Where it differs is the price. Those bulbs are cheap. This one costs even less.

Miracle LED claim this bulb can replace a 100 w bulb while only consuming 9 watts. I’m not sure what they mean by 100w, but I’m guessing it must be a 100w incandescent bulb and not fluorescent.

As you can probably imagine, a light that only uses 9 watts is not super powerful. That said, the Amazon listing says it emits 1900 umol.

Honestly, that is ridiculous. They don’t say what height that was measured at, but no matter how close you get to this bulb, no good PAR meter is going to read 1900. That figure is nowhere to be found on the Miracle’s own site, so I have no idea where the Amazon seller pulled that from.

Bottom line: this bulb is fairly dim and easily the least powerful on this list.

Due to the lower output, I doubt this light would be very effective as a seed starter, despite the claims. It could work for a couple of seeds in the same pot directly below the light, but not for a substantial amount of seeds. For that, the first light on this list is much better suited. And it really doesn’t cost too much more.

That light also has a better spectrum, thanks to the white diodes. This Miracle LED light emits only one wavelength: 475 nm, which is blue.

Miracle LED provide a one year warranty. Since the bulb is so cheap, you could get a bunch of them (ideally some blue, some white, some red) and use them in combination. Added up, they could be effective, similar to how you’d use a number of CFL bulbs to grow a single plant.

Blue LED grow lights are great for seeding or vegging. But the truth is, plants want more colors than just blue. For that reason, these fixtures are best suited for…

7 Myths LED Grow Light Companies Tell You

So you’re interested in buying the best LED grow light for indoor plants? You have come to the right place.

To make an informed decision, you should understand how plants use light, especially from artificial light sources. We are going to deconstruct a few myths in the industry to help you identify the best grow lights on the market.

Myth #1: “HPS puts out over 50% wasted light”

“This is why our purple 12-band LEDs are more efficient! Our perfect 12-band spectrum puts out the only light plants really need.”

If you see this quote, run! 🙂 Some LED companies say that the reason why LEDs are more efficient than High-Pressure Sodium bulbs is because plants don’t use yellow or green light. In other words, the reigning champion of grow lights for several decades, the mighty High-Pressure Sodium, is putting out a lot of “wasted light”. What?

Here’s what the LED companies haven’t been telling you. There’s a phenomenon known as the green gap for narrowband LEDs — they can’t create green, yellow or infrared wavelengths very efficiently. So when you look at the graph below, you’ll suddenly understand why we have purple grow lights. It’s because red and blue are the only colors narrowband LEDs are good at making! Also notice how narrowband LEDs only create very small “points” of color, which is why you might see 8, 10, or 12 bands being advertised as a full spectrum led grow light – it’s a company’s way of trying to deal with LED technology developed in the 1990’s.

The efficiency percentage of narrowband LEDs at different colors (wavelengths)

Truth: LEDs are more efficient than HID bulbs because they create light directly from electricity, and do not have to heat up a bulb.

But really, where are they getting the idea that purple light is the best for plants? Read on to Myth #2…

Myth #2: Plants Only Need Red and Blue (Purple) Light

Here is where the LED company will pull out their favorite chart – the Chlorophyll A/B absorption graph (see “Pigment Extract” in the below image). They’ll show their spectrum on top of this chart and say that they’re giving plants only the colors of light that they can absorb, or 100% usable light. Sounds great right? It’s more like a marketing trick.

Remember the colors that narrowband LEDs could create from Myth #1? Notice how red (

450nm) conveniently coincide with the colors most absorbed by the “Pigment Extract” which is Chlorophyll. In actuality, the leaf itself is absorbing more than just red and blue. Green and yellow light (500-600nm) are getting absorbed by the leaf, too. In fact, these colors are very important for the full development of the plant since that is what they experience when growing under the sun.

Absorptance spectra of spinach leafs

If you look closely at the graph, notice how different parts of the plant leaf absorb varying portions of light. The “Chloroplasts” are the centers of photosynthesis — notice how much green, yellow, and orange they absorb. Green doesn’t just “bounce off” of the leaves after all!

If you can imagine green and yellow light as the “free agents” that can slip by Chlorophyll A/B to other parts of the leaf, think about how a red and blue spectrum could fail. Red and blue light cannot easily penetrate past the first few layers of plant cells, into buds, or to the leaves below because Chlorophyll A/B is blocking those colors! See the illustration below where the narrowband Red/Blue LED having most of its light blocked by the leaf (e.g. Chlorophyll A/B) whereas HPS or broadband light penetrates past the canopy through to the leaves below.

Myth #3: Blue is for Veg, Red is for Flower

This myth originates from the ritual of switching between Metal Halide (MH) and High-Pressure Sodium (HPS) bulbs when transitioning from the vegetative stage to the flowering stage of growth. Growers use MH because it has blue light which is needed to prevent stretching. HPS bulbs have more yellow/orange light, which is important for rapid growth during flowering. Neither of these bulbs is designed for plant growth, but each is more suitable for a certain stage of plant growth than the other.

Since growers are in the habit of switching bulbs between veg and flower, LED companies provide two spectrum modes to increase marketability. Usually, the veg mode is almost 80 percent blue light. Studies show that giving your plants mostly blue light during veg is wasting the potential of your harvest. Your plants will grow slower, create smaller leaves, and won’t be prepared to grow big for the final yield.

Check out the image below illustrating the vegetative growth of lettuce under varying amounts of blue and green light. Watch what happens when blue light passes about 20 percent — the plants shrink! Think about the results that you might get from a grow light with more than 50 percent blue light. LED companies that “match” the chlorophyll A/B graphs will provide this much blue light, seriously decreasing yields. For curious minds, check out the study (quoted below) here.

As the fraction of blue light increased, leaf size and plant growth decreased significantly. However, while the addition of green light considerably reduced the leaf photosynthetic rate, it did not reduce plant growth.

Myth #4: UV LEDS Help Plant Growth

First things first, UVB light has shown benefits to certain plants, but only when applied at the correct intensity, for the proper length of time, and at the right time. Otherwise, UV light can be harmful to plants, let alone your eyes or skin — it’s the reason we use sunscreen and wear sunglasses when going outside.

All UV Rays can lead to eye damage. If your grow light emits UV, wear eye protection !

That being said, if used properly, could UV LED’s help plant growth? It’s a toss-up of whether it’s worth it when reviewing scientific articles. Most UV LEDs actually only produce UVA light, which can be safer and less damaging than UVB. However, the reason why UVB light is beneficial to plants is because it introduces damage and the plant responds with a defense, so UVB light is ideal.

What’s more, UV LEDs are not as efficient, more expensive, and burn out more quickly than other LEDs. With that in mind, it bears the question if using UVA LEDs is worth it, especially if that power could be redistributed to colors that are proven to increase plant growth.

See the graph below from an LED chip manufacturer to see the limited output range of UV LEDs:

Leading UVA/UVB LED supplementation bars last about 15,000 hours (vs the standard LED lifetime of 50,000) and cost hundreds of dollars, whereas a UVB bulb such as the T8 Reptisun 10.0 UVB cost about $15 and will last you an entire year if used for the flower period of your grow.

Myth #5: 1000W LED = 1000W HPS

  • The HPS bulb wattage the LED fixture is intended to replace.
  • An addition of the “highest rated power output” of LED chips.
  • The actual power draw in watts.

Myth #6: The More Lumens, the Better

Lumens are a measure of how bright light is to the human eye. Looking at the graph below, you can see that green/yellow light is the most visible to the human eye, with blue and red light being the least visible.

The sensitivity of the human eye to color. 400-500nm is blue 500-600nm is green/yellow/orange, and 600+nm is red

You may find white LED companies advertising Lumens because they can “beat” the other fixtures that emit mostly red and blue light. A Red/Blue light will score a low amount of lumens.

Each color of light has a different efficiency and plays a different part in a plant growth, so we need a plant-centric light measurement as a benchmark. This is called Photosynthetically Active Radiation (PAR), which weights all wavelengths from 400-700nm equally.

Be critical about videos comparing one LED light to another with a PAR meter. Many PAR meters on the market incorrectly read LED lights. If you’re really interested about this, check out Apogee Instrument’s superb presentation [Scroll down to “In-depth Look at PAR-Quantum Meters” click play and skip to

15:00]. If you’re a grower, you should understand the concept of how light is measured. And hey, pick up a quality light meter!

Truth: PAR is the correct light measurement for plants, and not lumens.

Myth #7: A High Center-Point PAR Reading Means the Brightest Light!

Most grow lights are only good at shining light directly below the fixture in a “spotlight”, so the most attractive light reading an LED company can advertise is the highest reading they can measure — the one right in the center of the light.

Plants easily burn with this type of focused LED light, which is one of the reasons you may want to pay attention to this reading: if a light is putting out over 800 umol.m .2 s 1 of PAR in the center, that is in the danger zone for burning your plants. You’ll have to raise the light to the point where the center isn’t so “hot”, which actually decreases the brightness for the rest of your grow area. Counterintuitive, huh?

Look for LED grow lights that cover the entire grow area like the our lighting systems. These systems help eliminate plant burn while keeping your entire grow area at a uniform light level.

7 Myths LED Grow Light Companies Tell You So you’re interested in buying the best LED grow light for indoor plants? You have come to the right place. To make an informed decision, you should