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9 Best LED Grow Lights for Cannabis

led grow lights

Ready to grow some incredible herb? Today, most growers choose LED grow lights for cannabis. (LEDs even come standard with most grow tent kits, which make it simple for new growers to use them.)

The best LED grow lights provide all the wavelengths you need to grow big, beautiful buds. Plus, they stay much cooler than their traditional HPS counterparts — helping you save on electricity.

Some of our reviews here cover an entire series of lights. In our reviews, you’ll find links to each size and wattage.

spider farmer Amazon Customer Reviews
  • Detachable driver
  • No fan
  • Daisy-chain can connect up to 15 lights
Price: $579.99 Shop at Amazon Shop now Read our review
ViparSpectra Dimmable LED Grow Lights Amazon Customer Reviews
  • Well known brand with excellent customer service
  • High quality light using the latest technology and dimmable for complete customization
  • Four sizes to choose from
Price: $89.99 Shop at Amazon Shop now Read our review
ViparSpectra Reflector-Series LED Grow Lights Amazon Customer Reviews
  • Three year warranty and 30-day money back guarantee
  • Reflectors increase PAR value
  • High quality internal fans for maximum cooling and efficiency
Price: $79.99 Shop at Amazon Shop now Read our review
GalaxyHydro Roleadro LED Grow Lights Amazon Customer Reviews
  • Two year chip replacement warranty and 30 day money back guarantee
  • Multiple light sizes and configurations to choose from
  • Best selling brand and 11 years of experience makes them a customer favorite
Price: $85.99 Shop at Amazon Shop now Read our review
Yehsense LED Grow Lights (1) Amazon Customer Reviews
  • Powerful lights at a low price
  • Comes in sizes ranging from 1000-2000 Watts
  • Hundreds of positive reviews
Price: $109.00 Shop at Amazon Shop now Read our review
Gavita grow lights Amazon Customer Reviews
  • Ideal for growers with low ceilings
  • Considered one of the most efficient LED lights by some expert growers (see review for details)
  • Gavita's E-series can be controlled externally (making it ideal for professional grow rooms and larger operations)
Price: $1,178.11 Shop at Amazon Shop now Read our review
full spectrum LED grow lights Amazon Customer Reviews
  • True full spectrum (with UV light as well)
  • Advanced cooling design helps you save on cooling bill
  • 5 year warranty
Price: $1,099.00 Shop at Amazon Shop now Read our review
Philzon LED Grow lights Amazon Customer Reviews
  • Two year warranty, 30-day money-back guarantee
  • Available in three sizes, each comes with a digital thermometer/humidity monitor
  • Very highly rated with over 800 positive reviews
Price: $172.40 Shop at Amazon Shop now Read our review
King Plus Double Chip LED Grow Lights Amazon Customer Reviews
  • 10W LEDs are brighter
  • Less energy consumption
  • Full spectrum
Price: $95.99 Shop at Amazon Shop now Read our review
Our Unbiased Reviews
  1. 1. Spider Farmer SF7000 LED Grow Lights

    Pros:
    • Detachable driver reduces cooling needs
    • Quiet fanless design
    • Daisy-chain can connect up to 15 lights
    • Can be folded in half for storage when not in use
    Cons:
    • Not as much light in the red spectrum as in the blue
    • Designed for five feet by five feet growing area
    • Can't daisy chain more than 15 SF7000 lights

    Spider Farmer is newer than most grow light companies — it was founded in 2009 — but their affordable LED grow lights have become wildly popular, with good reason. They’re affordable, durable, and come with an excellent customer service guarantee.

    With the release of the SF7000 series, Spider Farmer has created the perfect light for anyone growing in a five-foot by five-foot grow tent. Of course, thanks to the daisy-chain feature, you can also connect several of these lights (up to 15 lights) to cover a much larger grow room.

    Spider Farmer had previously won popularity with the SF2000 and SF4000, which are great for growing in smaller areas, but they added some new improvements to the SF7000 (in addition to being able to provide coverage for areas five-by-five feet and larger). They improved the driver, which is detachable and can even be stored outside your Spider Farmer grow tent. The SF7000 also includes ultraviolet and infrared diodes.

    The SF7000 is even capable of being folded in half when not in use. So if you need to free up storage space between harvesting and planting your next crop, this could be a helpful feature.

  2. 2. ViparSpectra Dimmable LED Grow Lights

    Pros:
    • Dimmable, allows for complete customization of your light schedule and configuration
    • Extremely bright and powerful with hundreds of positive reviews
    • Well known brand and excellent customer service
    Cons:
    • The product description lists the PAR 600 and PAR 700 as having the same coverage area, this may be incorrect information
    • These lights are heavier than other LEDs and may be harder to hang
    • Relatively expensive

    These ViparSpectra Dimmable LED Grow Lights stand out because dimmable LEDs can provide a greater level of customization for your lighting schedule.

    ViparSpectra is one of the best brands of LED grow lights because they consistently use the best technology available, and this dimmable series of lights is a great example. If you want to geek out on customizing your lighting schedule, dimmable LEDs are the way to go. 

    Dimmable LED grow lights allow you to not only switch between lighting configurations for vegetative and flowering growth stages but to adjust the percentage of veg/flowering to whatever level you want. These lights use secondary optical lenses in order to maximize 

    This means that you can have a custom setting for cloning, seedlings, early vegetative, late veg/early flowering, and late flowering. This level of adjustability is perfect for experienced growers who want to take their grow operation to the next level.

    This series comes in several sizes, including the 1000W LED, which replaces 400W HPS with an actual power draw of 274W, core coverage of 2.5’ x 2.5’, and max coverage of 3’ x 3’.

  3. 3. ViparSpectra Reflector-Series LED Grow Lights

    Pros:
    • Three year warranty and 30-day money back guarantee
    • Very well built and rugged design
    • High quality internal fans for maximum cooling and efficiency
    • Reflective coating surrounding LEDs increases PAR value with no extra energy consumption
    • Bloom and Veg switches on all models and some are dimmable
    Cons:
    • Reviewers complained of slow shipping
    • Some reviewers noted a smaller light footprint in their grow op than advertised
    • Not all models are dimmable

    This ViparSpectra Reflector Series stands out because it’s an excellent collection of grow lights that range from 300W to 900W. These lights are well designed, and they come with all of the features you would expect from a top-quality grow light.

    They include a mix of red, blue, and Infrared LEDs for all stages of plant growth. Each light has two switches to turn on and off the appropriate set of LEDs for vegetative or flowering growth stages. The 600W model has dimmable knobs instead of just on/off switches for even more customization.

    These LED lights run cool and the lights also have 4.72″ fans and large aluminum cooling heat sinks for dissipating any excess heat. They come with all of the necessary hanging equipment, and reviewers have noted that these lights are very well balanced and easy to hang.

    These grow lights are extremely durable and well made, and they come with a three-year warranty as well as a 30-day money back guarantee. Many reviewers appreciated the powder-coated black finish of these lights, as well as the quiet running fans, and the reflective coating around each LED that increases the PAR output of the lights significantly.

    You can choose from four different sizes:

    300W: Replaces 250W HID, Actual power draw 130W, Core coverage 1.5′ x 1.5′, Max coverage 2′ x 2′

    450W: Replaces 300W HID, Actual power draw 20W, Core coverage 2′ x 2′, Max coverage 2.5′ x 2.5′

    600W: Dimmable. Replaces 400W HID, Actual power draw 265W, Core coverage 2.5′ x 2.5′, Max coverage 3′ x 3′

    900W: Replaces 600W HID, Actual power draw 390W, Core coverage 3′ x 3′, Max coverage 4′ x 4′

  4. 4. GalaxyHydro Roleadro LED Grow Lights

    Pros:
    • Two year chip replacement warranty and 30 day money back guarantee
    • All models come with LED Bead and Zener design, meaning if one LED bruns out the entire light will not stop working
    • Super bright 10 Watt LEDs used on most models
    • Multiple configurations and spectrums to choose from
    • White light LED models use a true sunlight full spectrum.
    Cons:
    • It can be confusing to try and follow the GalaxyHydro Vs. Roleadro brands and models available
    • The manufacturer has no website or information available, lights are only sold on Amazon
    • Many available models do not have a ful spectrum, with as low as 9-band spectrums on some
    • Some information regarding coverage area was not accurate on the Amazon.com page and had to be verified with the manufacturer.

    These Roleadro Grow Lights stand out because they’re some of the best-selling LED grow lights on Amazon.

    Roleadro is one of the top-selling LED grow light brands on Amazon.com, with 11 years of experience in the industry. You may be familiar with the brand GalaxyHydro. Roleadro acquired this company a few years ago. Today, they are the the sole manufacturer of Galaxyhydro LED grow lights.  

    All of these lights listed below come with a two year LED chip replacement warranty and 30-day money back guarantee. 

    Galaxyhydro lights are pretty basic as far as their quality, but for the low cost, they are a popular choice for small home growers. If you want a good quality grow light for cheap, they are a good choice. These lights also work well as inexpensive supplemental lighting for the dark corners of your grow room. 

    Galaxyhydro lights come in two sizes: 

    1,000 Watt: Roleado describes this light as having a higher concentration of red LEDs in order to boost your yield during the flowering stage (This may make the light less suitable for maximum vegetative growth). This light uses 10W Epistar LEDs with a 90-degree optical lens on each one. 

    The light utilizes LED Bead and Zener design to ensure that if one LED burns out, the rest of the light stays working. This light consumes only 135 watts of actual power. Each light has two high-speed cooling fans and a built-in aluminum heat sink. 

    Core coverage 2’ x 2’, Max coverage 3’ x 3’ 

    1,500 Watt: The 1500W light uses the same Epistar LEDs as the 1,000 Watt light, as well as equivalent LED Bead and Zener technology. It comes with an efficient aluminum heat sink and two cooling fans. This light replaces a 4,000 Watt HPS and has an actual power draw of 250 watts. 

    Core coverage: 2.5′ x 2.5′, Max coverage 3.5′ x 3.5′

    Roleadro LED grow lights come in two options: UFO style or white, full-spectrum LEDs: 

    UFO Style LED Grow Light: This light comes in two sizes, 300 Watt or 600 Watt. Both sizes have a nine-band spectrum and are suitable for vegetative growth. They are best used for seedlings or clones, or as supplemental lighting during the vegetative stage.  

    75 Watt: This small light is “white” instead of a combination of red and blue, providing a full spectrum to imitate sunlight. Each LED has a 60-degree reflector to increase coverage. 

    There is an aluminum cooling plate and this extremely thin panel light does not need any noisy fans to stay cool. This is a very small light, best for seedlings or for supplemental lighting.  

    600 Watt: This 600W light uses 3500K full-spectrum white LEDs to simulate natural sunlight. This light utilizes LED Bead and Zener design to ensure that if one bulb burns out, the other LEDs continue to work. This light uses a combination of 90 and 120-degree lenses to ensure maximum coverage. 

    You can daisy chain multiple units together for a custom lighting solution in your grow room. Each light comes with high speed, quiet running fans and upgraded aluminum heat sinks for efficient heat dissipation. 

    Actual power draw: 134 Watts

    1,000 Watt: This light uses 100 individual 10 Watt LEDs with an actual power draw of 185 Watts. 

    Like the 600 Watt light, it uses LED Bead and Zener technology with 90 and 120-degree reflectors for the best performance and high canopy penetration. It comes with built in fans and aluminum heat sink for cooling. Each light can be easily daisy chained. 

  5. 5. Yehsense LED Grow Lights

    Pros:
    • Each light has a Veg/Bloom switch for customization
    • Comes in larger sizes than most brands - Up to 2000 Watts
    • Customer satisfation is high with hundreds of positive reviews
    Cons:
    • Not a US based brand, customer service based in China
    • Only three options to choose from
    • May not be quite as high quality as pricier brands

    The Yehsense LED grow light series is an excellent choice for growers who need powerful lights for a lower price. Yehnsense offers lights with higher wattages than other brands, and at a price that is almost too good to be true. This series comes in three sizes: 

    1000 Watts: Replaces 1000W HPS, Actual power draw 180W, Core coverage 3.5’ x 3.5’, Max coverage 5.5’ x 5.5’ 

    1500 Watts: Replaces 1500W HPS, Actual power draw 265W, Core coverage 5.4’ x 5.4’, Max coverage 6.5’ x 6.5’

    2000 Watts: Replaces 2000W HPS, Actual power draw 380W, Core coverage 6.8’ x 6.8’, Max coverage 7.8’ x 7.8’

    These lights have a Veg/Bloom switch on each one, allowing you to fully customize your growing schedule and provide the best light spectrum for your plants no matter what stage of growth they are in. 

    Yehsense lights can be easily daisy-chained together if you need even more coverage. These lights come with a three-year warranty and 90-day money-back guarantee, which is longer than almost any other brand on the market today.

  6. 6. Best Commercial LED Grow Lights: Gavita Pro 1700e LED 120-277 Volt

    Pros:
    • Ideal for growers with low ceilings
    • Considered one of the most efficient LED lights by some expert growers (see review for details)
    • Gavita's E-series can be controlled externally (making it ideal for professional grow rooms and larger operations)
    Cons:
    • External controller sold separately (see review for details)
    • Power cord sold separately
    • Expensive

    The Gavita Pro E-Series 1000e stands out because it’s the LED light recommended by professional marijuana growers like Evan Anderson, owner of 14er Holistics, a renowned cannabis brand in Colorado.

    “Gavita recently put out a LED light that can rival ceramic metal halide lights,” Anderson explained, pointing out this model. “LED and ceramic metal halide lights are both moving forward aggressively in terms of efficiency.”

    Anderson’s licensed cultivation facilities employ ceramic metal halide lights, not LED lights. But he understands why certain growers might prefer LED.

    “You want the light that will make your plants the happiest with the lowest heat loading,” he says. 

    This is also a double-ended (DE) grow light, which is basically the standard in all professional-level grow rooms. (A double ended grow light operates at a much higher efficiency than single ended grow lights, saving you money on energy costs in the long run.)

    Growers with ceilings less than 8 feet from their plants sometimes say they prefer LED lights like these, because they can keep their room sufficiently cool (and won’t burn their plants).

    These are perfect for low ceilings: At 9.7 inches, this “slim line” light is one of the shortest grow lights available today.

    They would be perfect in an industrial grow room that has vertically-stacked rows of plants.

    Gavita’s E-series, which was designed for professionals and large grow rooms, can be controlled externally with the Gavita controller (sold separately). Thanks to these external controls, you can further customize your light cycle. You can set safety features (like programming your lights to be dimmed if temperatures reach a certain threshold), or an auto shut-off feature.

    Get professional, and upgrade your grow with this expert-approved LED light.

  7. 7. Black Dog LED PhytoMAX-2 200 LED Full Spectrum Grow Lights

    Pros:
    • True full spectrum (with UV light as well)
    • Advanced cooling design helps you save on cooling bill
    • 5 year warranty
    • Powerful footprint without hotspots
    • Black Dog has been in LED light market for longer than most other companies
    • Quiet
    Cons:
    • Designed for plant needs, not human eyes
    • You may need serious sunglasses while working in your grow room
    • Not the cheapest grow light on this list

    The Black Dog LED PhytoMAX-2 200 LED Full Spectrum Grow Lights stand out because they’re extremely powerful, with a well-researched light spectrum that provides all wavelengths needed by plants.

    Black Dog has a reputation for excellent customer service — including the five-year warranty on these lights.

    We spoke to Noah Miller, the CEO of Black Dog LED, about why his company’s lights outperform so many competitors.

    “Black Dog LED has been making lights longer than almost every company in the market today,” Miller said.

    And their lights are designed specifically for the unique needs of cannabis plants. Over the years, the company has focused on two main factors: power and spectrum.

    “Most companies simply use broad-spectrum white LEDs that are developed for the human eye,” he explained. “We have developed a spectrum that not only delivers the best yields, but also the highest quality flower, as well as helping to maintain a proper plant structure for indoor growing.”

    Because these have been designed with a focus on cannabis plant needs (and not human eyes), you may need to wear some heavy-duty sunglasses while working in your grow room.

    Reviewers appreciate the great customer service, incredible power, and the quiet noise level from these lights, even while the fans are operating.

    These lights emit a true full-spectrum (including UV rays). Miller explains that this makes them optimal for growers seeking to maximize potency — whether they evaluate it in terms of cannabinoids or terpenes.

    For more of our interview with Black Dog CEO Noah Miller, scroll down to the bottom of this article!

  8. 8. Philzon LED Grow Lights

    Pros:
    • Inexpensive in comparison with other brands but still high quality
    • Veg and Bloom switches allow you to customize your light based on your plants' growth stages
    • Double cooling fans in each light
    Cons:
    • New brand, not as experienced as some others
    • Lights are not dimmable
    • Based in China, not the US, so customer service may not be as responsive as US brands

    These Philzon Grow Lights stand out because, for a relatively new brand, they have a surprising number of positive reviews. Plus, Philzon LED grow lights are high quality, full-spectrum, and tested for maximum efficacy. 

    These lights come in three sizes: 

    600 Watts: Replaces 400W HPS, Actual power draw 108 Watts, Coverage area 2′ x 2′ 

    900W: Replaces 600W HPS, Actual power draw 220 Watts, Coverage area 2.5’ x 2.5’

    1200W: Replaces 800W HPS, Actual power draw 305 Watts, Coverage area 3’ x 3’ 

    These lights come with a two-year warranty and a 30-day money-back guarantee. They also come with a digital thermometer and humidity reader for your grow room. Philzon does not use reflectors in order to minimize heat generation.

    Each light can be daisy-chained to another, even if they are different wattages. They all have double cooling fans to extend their lifespan, and Veg/Bloom power switches so that you can easily switch the light spectrum for different growth stages. 

  9. 9. King Plus Double Chip LED Grow Lights

    Pros:
    • 10W LEDs consume less energy for a greater light output
    • Full spectrum lighting with red blue, yellow, white, IR and UV
    • Double LED lights mean more efficiency and greater light coverage
    • Thicker case, ventilated glass cover and fans included for better heat dissipation
    • Three year warranty and excellent cover service
    Cons:
    • KingLED has not been in business as long as other trusted manufacturers
    • They do not provide as much information about actual wattage and coverage areas
    • The lights have no reflectors

    These King Plus Double Chip LED grow lights stand out because they’re more affordable than most other lights on this list. And they’re powerful.

    King LED is based in China, and they’ve been developing their lights for over five years. They own their own factories and production lines, so they are able to adapt their lights with the newest technology quickly and efficiently. 

    The Double Chip LED series is exactly what it sounds like. These lights feature 10W LEDs with two chips each instead of the standard 3W or 5W. This makes them much brighter, with greater canopy penetration. It also means more energy savings for the grower. 

    These lights come with a three-year warranty and a 30-day money-back guarantee. Each light has Veg and Bloom switches so that you can switch between growth stages without having to replace the lights. 

    These lights have high speed, quiet-running fans as well as aluminum heat radiators to stay cool, at an average temperature of 50 to 60 degrees Fahrenheit. 

    This series comes in three sizes: 

    600W: Replaces 250W HPS, Coverage area 3’ x 3.4’ 

    1000W: Replaces 600W HPS, Coverage area 2’ x 3.5’

    12000W: Replaces 800W HPS, Coverage area 3.5’ x 5.2’

What are the best LED grow lights on Amazon?

All the options reviewed on this list are available on Amazon!

Are these the best LED grow lights for indoor plants?

Yes! All of these provide the necessary light spectrum to finish cannabis plants indoors.

(You could also put them in a mushroom grow tent -- but when you're growing mushrooms, you can usually get away with a cheaper light source than these.)

That's part of the big hubbub about LED lights these days.

LEDs provide optimal light wavelengths needed for plant growth, according to a NASA study.

Plus, it's easy to manipulate the schedule and configuration of colored LEDs in order to boost vegetative or flowering growth, depending on what stage your plants are in.

Maybe you heard someone talking poorly of LED lights in the past. But this industry is rapidly evolving.

"The efficiency gains [in LED lights] over the last 6 to 8 years have blown my mind," says Noah Miller, the CEO of Black Dog LED. "However, because the engineers making the LEDs have done such a great job, we are starting to reach the limits of efficiency."

In other words: it's a great time to switch your grow over to LED (if you haven't done so already).

Who makes the best LED grow lights?

Professional cannabis growers agree that makers of LED lights are moving forward aggressively in terms of efficiency.

So the brand making the best and most efficient version is always up to debate. (And growers do engage in heated debates on this very topic.)

Check out the detailed reviews above for more information.

It's helpful to look for a company that's known for great customer service (and long warranty times), in case you need assistance.

Do I need LED lights? How do I choose the best ones for my plants?

Today, many new cannabis consumers are trying their hand at growing -- or diving into the legal industry as a commercial grower.

When choosing your LED lights, after finalizing your budget, your next main concern should be the light spectrum.

"A better spectrum can also do more with less," Miller explains, "which ultimately saves the grower more money [on her electric bill]."

And, as professional growers know, growing indoors certainly has its perks. You can customize your environment completely with grow tents, hydroponic watering systems, different nutrient solutions, and more.

Are LED Grow Lights Better Than HID? 

Yes. LED grow lights are superior to HID for a variety of reasons, including energy efficiency, safety, flexibility, and longevity. 

Back when LED technology was brand new, LED grow lights were considered inferior to HID (High-Intensity Discharge) grow lights including MH (Metal Halide) and HPS (High-Pressure Sodium). LEDs were not as powerful or as reliable, and as a result, professional growers did not trust them to give the quality and yields they wanted. 

These days, things have definitely changed. LED technology has grown better, brighter, and more advanced. LED grow light bulbs are more powerful than ever. CREE, SMD, and reflector technologies have brought LEDs to the forefront of professional grow operations. Individual LED diodes are brighter than ever and the addition of reflector cups helps to increase canopy penetration better than HID bulbs could ever achieve. 

LEDs are far more energy-efficient than HID grow lights. Why? Mainly because they do not put out nearly as much heat. HID bulbs get extremely hot, while LEDs remain cool to the touch even after hours upon hours of use. HID bulbs pose a fire risk, especially when left on unattended for 18 to 24 hours per day during vegetative growth. You also have to be careful not to hang HIDs too close to your plants or you could scorch them.

Because HID was the industry standard for so long, LED manufacturers will usually list their grow light wattage in terms of its HID equivalent, although they are not always listed as the exact equivalent wattage. For example, the Viparspectra Reflector Series 900W LED grow light is actually equivalent to a 600W HID. Make sure to check the manufacturer's specifications for your grow light’s coverage before purchasing.

LED grow lights consume far less energy than the wattage that is described in their names. For example, the PlatinumLED P9 CREE 855W LED grow light only consumes a maximum of 550W during Boost mode, and on the lower end only 243W during vegetative growth. 

LED grow lights may be more expensive than HID upfront, but they will save you money in the long run. HID bulbs must be replaced yearly if you want to maintain the same level of plant growth. MH and HPS bulbs start to lose intensity after about a year, and even though they still power on, your yields will suffer if you are not using bright new bulbs each year. LED grow lights can be used year after year with no change in brightness. 

LED lights are lightweight and easy to hang. Because HIDs use ignited gas to create their wavelengths of light, a ballast is required to regulate the voltage reaching the bulb. These ballasts are heavy and bulky, and when combined with the bulb, reflector hood, and inline fan ducting, it becomes a huge hassle to hang HID grow lights. LEDs, on the other hand, are usually a lightweight panel that can be hung with thin wires. While HIDs can only be hung horizontally,  LED grow lights can be hung vertically or horizontally in order to reach even the darkest corners of your grow room.

As mentioned earlier, HID refers to both Metal Halide (MH) and High Pressure Sodium (HPS) bulbs. MH bulbs are suitable for vegetative growth, while HPS lights are suitable for flowering. This means you have to switch your bulbs out every time you are ready to enter the next growth stage. Many LED grow lights remove this hassle and make it as easy as flipping a switch. 

Do LED Grow Lights Use a Lot of Electricity? 

LED grow lights are very energy efficient and they do not use a lot of electricity. Traditional HID grow lights consume a ton of electricity, in fact paying for the electricity used to be one of the major costs of homegrown weed. Each HID bulb can consume anywhere from 100 Watts to 1,000 Watts, so it depends on the size of your grow, but switching to LED grow lights can save you 50% to 70% in actual power consumption. 

Many LED grow lights are still described in the wattage of their HID equivalent in terms of brightness. As you can see in the list above, though, many brands do not use the exact same wattage equivalent in their naming conventions - Make sure to check the manufacturer’s specifications on your grow light before purchasing. 

It is a good idea to go by the recommended coverage area for a particular LED grow light as opposed to the HID equivalent, as this measurement is far less subjective. 

This calculator tool can help you figure out how much electricity your LED grow light will consume and what the cost will be on your power bill. Just keep in mind you will need to adjust the hours per day based on vegetative vs flowering light schedules. 

What Size LED Grow Light Do I Need? 

In order to figure out what size LED grow light to buy, you need to calculate your grow area square footage and know how many plants you will grow. Perhaps you already have a grow tent picked out and are not sure how many plants to grow, or maybe you already know how many plants you want but are not sure how big of an area you need to dedicate to them. 

We can make this easy for you! For marijuana plants, you want to make sure you have a minimum of 50W per square foot of area. All you need to do is figure out the area (length x width) of your grow tent or room, and multiply that number by 50. 

If you are starting with a specific number of plants and figuring out the size of your grow room, it is still easy to calculate. Each cannabis plant requires at least one square foot of space in order to thrive.

As an easy reference, you need 50W and one square foot of space for each weed plant. This is a minimum amount - If you have the space and the budget, more is better, especially during vegetative growth!

Here is an easy reference list for up to 10 plants:

  • 1 plant: 1 square foot: 50W LED grow light
  • 2 plants: 2 square feet: 100W LED grow light
  • 3 plants: 3 square feet: 150W LED grow light
  • 4 plants: 4 square feet: 200W LED grow light
  • 5 plants: 5 square feet: 250W LED grow light
  • 6 plants: 6 square feet: 300W LED grow light
  • 7 plants: 7 square feet: 350W LED grow light
  • 8 plants: 8 square feet: 400W LED grow light
  • 9 plants: 9 square feet: 450W LED grow light
  • 10 plants: 10 square feet: 500W LED grow light

Also, keep in mind that grow light brands will typically tell you the recommended square foot coverage of each of their grow light models. Make sure to check these numbers before purchasing your grow light.

How Many LED Grow Lights Do I Need? 

The number of LED grow lights you need depends on a few factors. First, how many plants are you growing? You can see our chart above for a general recommendation of how much wattage is required per plant. 

Second, are you planning on cloning or growing from seed? Baby weed plants have different light requirements, so you may wish to buy a separate grow light for this purpose. Many growers prefer to use T5 fluorescent lights for seedlings and clones. You can also use smaller, less expensive LED grow lights -- like LED grow lights under $500.

Finally, do you need supplemental lighting for dark areas of your grow room? You can maximize coverage by using enclosed grow tents or by installing reflective mylar sheeting in your grow room. Still, if you have a very large grow room you may end up with some corners that are not fully lit by horizontal LED grow lights. In this case, purchasing a few extra supplemental lights to hang vertically can make a big difference. 

How Far Should LED Lights Be From Plants? 

LED grow lights do not pose the same risk of burning plants as HID bulbs, but their light is extremely intense and can bleach the tips of your plants. It is best to mount them on easily adjustable lines so that you can raise them as your plants grow taller.

You may be surprised to learn that LED grow lights must be hung even farther away from the canopy than HID lights. Because LED grow lights offer such a powerful light spectrum, it can be too intense and overwhelming to the plants and it can cause them to look bleached. This will, of course, affect the yield and quality of your buds. 

  • Small lights under 200W should be hung at least 15” above your plants, and around 20” for seedlings.
  • Medium-sized lights under 800W should be hung between 20” to 26” above, and
  • Large lights over 800W should be hung between 26” and 45” above your plants. 

The best way to know exactly how high to mount your LED lights is to check the manufacturer’s recommendation. They should list a height for both vegetative and flowering growth, because flowering plants require a bit more intensity. 

Can LED Grow Lights Harm Your Eyes?

The short answer is no. LED grow lights are not a danger to your eyes or eyesight. According to a research paper done by CELMA (Federation of National Manufacturers Associations for Luminaires and Electrotechnical components in the European Union), LED manufacturers must follow strict design specifications for consumer safety. Hobby growers and home growers are at no risk when using LED grow lights regularly and responsibly.

But what do the experts mean by "regularly and responsibly?" To put it simply, you should not stare directly into an LED grow light, any more than you should stare directly into any super bright light. Grow lights are designed to mimic the sun, and often include UV bulbs along with red and blue light.

You've probably read about the potential dangers of excessive blue light emitted by screens. Blue light has the shortest wavelength on the visible light spectrum. It is the closest visible light to UV light, which we know can damage eyes (as in cases of snow blindness).

While blue light is okay in small doses, staring at a screen or LED light-emitting blue light for hours on end can hurt your eyes.

For home growers, the occasional trip into your grow room or peek into your grow tent is not enough to cause concern. If you are planning on spending many hours with your plants, such as in a professional setting, you may wish to purchase light-blocking glasses

These glasses can also be helpful for growers while looking at their plants. Instead of seeing your plants awash in colors, the glasses help you see them in natural light, which can be helpful for spotting any issues early.

Many grow light brands have their own special light blocking glasses that work with their LED configurations. Larger brands like Apollo have their own models. You can also purchase a general-use model that will work with most lights.