The Best LED Grow Lights 2018

Looking for an LED grow light? We’ve reviewed all of the best LED grow lights in 2018 so you so you can find the perfect light for your budget and setup.

the best led grow lights

It’s pretty simple: light is food for your cannabis plant.

If you want to achieve big yields, you need to feed it high-quality light.

Unfortunately, this is where many new growers fail.

Choosing the right grow light is no easy task. There are literally hundreds of options to choose from and every grow space has different requirements.

So how do you find the right grow light for your needs?

Well, this article should help 🙂

Not only have we explained how you should choose a grow light, we’ve also reviewed the top rated and best selling grow lights of 2018 and picked our winners based on value, functionality, and quality.

The Best Light for Growing Weed in 2018

Heads up! We’ve reviewed a LOT of great grow lights below. To save you some reading time, we’ve added them all to this to this handy comparison table.

The full reviews are below.

ImageAward / ModelCoverageHPS
Equiv
Spectrum
🏆 WINNER
★Best overall grow light 2018

VIPARSPECTRA Reflector-Series 600W
Veg
4 sq ft at 24"
Flwr
3 sq ft at 24"
600wFull
inc UV & IR
2nd place
★Best overall grow light 2018

Advanced Platinum Series P300 300w
Veg
4.5 sq ft at 18"
Flwr
3 sq ft at 18"
400wFull
inc UV & IR
3rd Place
★Best overall grow light 2018

VIVOSUN 600W Full Spectrum LED
Veg
4 sq ft at 24”
Flwr
3 sq ft at 24”
600w Full
inc UV & IR
🏆 WINNER
★Best value grow light 2018

VIPARSPECTRA Reflector-Series 300W
Veg
2 sq ft at 24"
Flwr
1.5 sq ft at 18"
300wFull
inc UV & IR
2nd Place
★Best value grow light 2018

Phlizon Newest 600W
Veg
3 sq ft at 24"
Flwr
2.5 sq ft at 24"
400wFull
inc UV & IR
3rd place
★Best value grow light 2018

BESTVA 600W LED Grow Light
Veg
2 sq ft at 24"
Flwr
2 sq ft at 18"
600wFull
inc UV & IR
🏆 WINNER
★Best budget grow light 2018

Shengsite UFO 250 50w LED
Veg
1.75 sq ft at 20"
Flwr
N/A
50wFull
inc UV & IR
2nd place
★Best budget grow light 2018

UNIFUN 45W LED Grow Light
Veg
1.5 sq ft at 18"
Flwr
N/A
45wFull
inc UV & IR
3rd place
★Best budget grow light 2018

Roleadro LED Grow Light Bulb
Veg
1.5 sq ft at 18"
Flwr
N/A
45wRed/Blue
🏆 WINNER
★Best tiny space grow light 2018

ACKE LED Panel Grow Light
N/A40wFull
inc UV & IR
2nd place
★Best tiny space grow light 2018

AMAZINGCATS 18W Dual Head Timing Grow Lamp
N/A18wFull
inc UV & IR
3rd place
★Best tiny space grow light 2018

TaoTronics 12w Single Grow Bulb
N/A12wRed/Blue

 

★ Best overall led grow light 2018 ★

If money isn’t an issue for you and you’re looking for the perfect yield, then these three grow lights will provide you with everything you need to max out photosynthesis and supercharge your crop.

Check latest price on Amazon

Veg Area Coverage: 4 x 4 coverage at 24”
Flowering Area Coverage: 3 x 3 at 24”
Power: Replaces up to 600 watt HID/HPS; Consumes 285 watts
Dimensions: 11.8 x 14.1 x 3.5 inches
Warranty: 3 years warranty + 30 days money back guarantee
Spectrum: Full spectrum (including UV & Infrared); 12 band spectrum
Weight: 13.7 lbs
Lifespan: 100,000 hours
Best for: Veg & Flower Stages

Don’t be surprised if you see VIPARSPECTRA on our list more than once! This brand is extremely popular, and for a good reason!

This 12-band spectrum light is enough to power a full 4’ x 4’ tent through the veg stage. It replaces up to a 600w HID light, but only uses 285 watts of energy, so it’s very efficient for its size!

This light is also great for a grower who needs a little extra help with temperature control and air circulation. This light features three powerful fans to help keep the light running at a low temp and also help circulate the air throughout your grow tent!

Check out the full review of this light here.

2nd Place
Advanced Platinum Series P300 LED Grow Light

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Veg Area Coverage: 4.5ft x 3.8ft coverage at 18″
Flowering Area Coverage: 3ft x 2ft at 18″
Power: Replaces up to 400 watt HID/HPS; Consumes 180 watts
Dimensions: 8.25 x 19 x 3 inches
Warranty: 5 years warranty + 3-month back guarantee
Spectrum: Full spectrum (including UV & Infrared); 12-band spectrum
Weight: 13 lbs
Lifespan: 100,000 hours
Best for: Veg & Flower Stages

You can’t do much better in terms of quality than the advanced platinum series by PlatinumLED. This series of lights is the definitely the premium crop of LED grow lights.

The P300 is one of the smallest and most affordable lights of the series and is PlatinumLEDs most popular grow light.

Every part of this grow light screams high-quality. From the American-made LED’s to the 12 bands of wavelengths (including infrared and UV) to the highest PAR per Watt ratio we could find in any LED light, this light features another amazing upgrade or feature at every turn.

PlatinumLED also stands by all of its lights with a fantastic 5-year warranty and 3-month money-back guarantee.

This light is best for the grower who wants the best quality possible with high-end construction and reliability. This light is literally everything you could want in a full-cycle grow light!

Check out our full review of this light here!

3rd Place
VIVOSUN 600w LED Grow Light

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Veg Area Coverage: 4 x 4 coverage at 24”
Flowering Area Coverage: 3 x 3 at 24”
Power: Replaces up to 600 watt HID/HPS; Consumes 270 watts
Dimensions: 20 x 15 x 5 inches
Warranty: 3 years warranty + 30 days money back guarantee
Spectrum: Full spectrum (including UV & Infrared)
Weight: 13.25 lbs
Lifespan: 100,000 hours
Best for: Veg & Flower Stages

VIVOSUN are usually known for their top quality grow tents, but today we’re excited to feature one of their lights! This 600w LED boasts many of the same features as the others in this category but also has a special bonus feature.

Because they work in tents, they bring a unique perspective to lights. Unlike the others on this list, this light features an enhanced cooling system.

The fans in this light are made with two reinforced steel fans; they run about 26% cooler than your average LED, so you can rest easy knowing this one won’t overheat your grow space.

This light is the least expensive in this category, and best for growers who want top quality, without totally breaking the bank. It misses out on the top spot because the brand doesn’t have much experience in lights, but we’re hoping to see more VIVOSUN lights in our lineup next year!

Check out the full review of this light here!

★ Best value led grow light 2018 ★

Looking for the best value for money? We’ve picked the top three lights that give you the biggest bang for your buck. Maximum function for minimum cost.

🏆 WINNER
VIPARSPECTRA Reflector Series 300w LED Grow Light

Check latest price on Amazon

Veg Area coverage: 2 x 2 ft at 24”
Flowering Area coverage: 1.5 x 1.5 ft at 18”
Power: Replaces up to 250 watt HID; Consumes 136 watts
Dimensions: 12.6 x 7.9 x 3 inches
Warranty: 3 years warranty + 30 days money back guarantee
Spectrum: Full spectrum (including UV & infrared)
Weight: 5.6 lbs
Lifespan: 100,000 hours; 18 hr daily limit
Good for: Veg & Flower Stages

For many new growers, properly lighting a grow space can be one of the most confusing and challenging aspects of growing. If that’s you, don’t worry! There are some really affordable lights that are not overly complicated and will work for the entire life of your plant.

The VIPARSPECTRA line of LED lights is the one of the most popular, and for good reason! These lights pack a lot of features and benefits into a small and affordable package. Even better than that, they take some of the stress out of growing since you can use them for both the veg and flower stages. No changing lights!

Best for: The V300 is the smallest in the line, but don’t judge a book by its cover! This light will cover an entire 2 x 2 grow tent through the veg stage (1.5 x 1.5 during flower), which is great for

home growers with small tents or beginners who don’t have a lot of money to spend on their startup.

Need something a little stronger? Don’t worry! VIPARSPECTRA makes a 600w and a 900w version of this light!  Want a full review of the V300? Click here!

2nd Place
Phlizon Newest 600w LED Grow Light

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Veg Area coverage: 3 x 3 ft at 24”
Flowering Area coverage: 2.5 x 2.5 ft at 24”
Power: Replaces up to 400 watt HID/HPS; Consumes 108 watts
Dimensions: 6.7 x 15.7 x 2.36 inches
Warranty: 2 years warranty + 30 days money back guarantee
Spectrum: Full spectrum (including infrared)
Weight: 4.85 lbs
Lifespan: 100,000 hours; 16 hr daily max
Best for: Veg & Flower Stages

Our Runner-Up in this category is the Newest model from Phlizon, and this model really is a great one! Phlizon makes up for its lack of name recognition by providing a product with full spectrum lighting, dual switch control, and an excellent energy efficiency rating.

If you’re looking for an excellent full-spectrum light for a small indoor grow, this light is a perfect choice. It is both affordable and energy-efficient, making it a great investment for a beginner grower!

Best for: Like the VIPARSPECTRA, this awesome light features two independently controlled switches. The “VEG” switch turns on blue lights, which are better for growing plants, and the “BLOOM” switch turns on red lights, which help grow denser, fuller buds. You can also choose to have both switches on if you are growing and flowering in the same tent. This is a really awesome feature since you won’t have to change out your lights when you switch to the flower cycle.

This LED uses only 108 watts of electricity, making it one of the most efficient LEDs on the market, but if you need more power there is also a 900w and 1200w version of this light available! Check out our full review here.

3rd Place
BESTVA 600W LED Grow Light

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Veg Area coverage: 2 x 2.2 ft at 24”
Flowering Area coverage: 2 x 2.2 ft at 24”
Power: Replaces up to 400 watt HID/HPS; Consumes 132 watts
Dimensions: 11.4 x 7.9 x 2.8 inches
Warranty: 3 years warranty + 30 days money back guarantee
Spectrum: Full spectrum (including infrared)
Weight: 5.71 lbs
Lifespan: 100,000 hours
Best for: Veg & Flower Stages

Wrapping up our winners for this category is the BESTVA 600w LED. This light has many of the same features as the others in this category, making it a really great option for a home grow operation. The only downside is the coverage area… this one is just a little bit smaller than the others, while also coming in most expensive.

The other downside is that BESTVA is a newer brand, so we don’t know much about their customer service. The reviews of this light are excellent, and they offer a great warranty, so we’re hopeful that this one will stay on our list for a while!

This light is best for the grower who wants a good return on investment and doesn’t like to buy name brand!  Check out our full review here.

★ Best budget led grow light 2018 ★

On a tight budget? We’ve picked three grow lights that will do a solid job for minimal investment.

🏆 Winner
Shengsite 50w LED Grow Light

Check latest price on Amazon

Veg Area Coverage: 1.75 x 1.75 ft at 20 inches
Flowering Area Coverage: NA
Power: 50 watts
Dimensions: 13.1 x 13.1 x 1.2 inches
Warranty: 12 months warranty + 30 days money back guarantee
Spectrum: Red/Blue
Weight: 2.1 pounds
Lifespan: 50,000
Best for: Veg only!

Our winner in this category really stands apart from the others. It’s more powerful, covers a bit more space, and features a cute circular design instead of the boring rectangle we’re used to. Check out our full review here.

If you’re a new grower with a limited budget, there’s a really good chance you’ve converted your closet into a makeshift grow room, amirite? This light is absolutely perfect to be hung from a closet rod!

Like this want but want to up the ante a little bit? For just a few extra dollars you can upgrade to a full spectrum version with infrared lights, which is a very worthwhile investment. Still think this is too bulky for your needs? Keep reading for our review of the best lights for tiny spaces.

2nd Place
UNIFUN 45w LED Grow Light

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Veg Area Coverage: 1.5 x 1.5 ft at 12-18 inches
Flowering Area Coverage: NA
Power: 45 watts
Dimensions: 12.2 x 12.2 x 1.2 inches
Warranty: 12 months warranty + 30 days money back guarantee
Spectrum: Full spectrum (including Infrared)
Weight: 2.47 pounds
Lifespan: 50,000 hours; 16-hour daily maximum
Best for: Veg only!

Budget growers should always be focusing on one plant at a time, and this Unifun light is perfect for hanging in a small grow space. This is the only light in the budget category that offers full spectrum lighting, including Infrared, which means its the best choice if you’re looking to maximize your vegetative growth.

Set this light up about 18” from the top stem of your plant and watch it grow like a weed, no pun intended.

This light is best for the first time grower who has a little space and a small grow tent, but not a lot of money to invest in lighting. Just remember, since this is for the veg stage only, you’ll have to buy a second light in a couple of months in order to flower your baby. Check out the full review here.

3rd Place
Roleadro 45w LED Grow Light

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Veg Area Coverage: 1.5 x 1.5 ft at 12-18 inches
Flowering Area Coverage: NA
Power: 45 watts
Dimensions: 10.8 x 10.8 x 1.3 inches
Warranty: 12 months warranty + 30 days money back guarantee
Spectrum: Red/Blue
Weight: 1.7 pounds
Lifespan: 50,000 hours
Best for: Veg only!

For our Budget Grow category we really wanted to highlight some options for folks who really want to get growing with a small startup cost, and this Roleadro 45w LED really does the trick!

The absolute best part of this light is how little it weighs… it is the lightest light in our list at only 1.7 pounds! This is nice if you have a makeshift grow space or need to wall mount your lights… these little guys won’t resist being installed however you see fit!

This light is best for a single seed beginner grower with an unconventional grow space. We recommend that you buy two of these lights to start and flank them diagonally on either side of your plant.

The double lights will be a mega boost in wattage (90 instead of 45 watts), and you’ll still pay less than the cost of our Value lights!  Check out the full review of this light here!

★ Best small space led grow light 2018 ★

🏆 Winner
ACKE LED Grow Panel Light

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Power: 40 watts
Warranty: 12 months warranty
Spectrum: Full Spectrum
Weight: 0.66 pounds
Lifespan: 50,000 hours; 16-hour daily maximum

The first light in our Tiny Spaces category is this versatile grow panel light by ACKE. We love that this light weighs less than a pound and comes in two panels that can be rearranged at multiple joints.

Every square inch of this 40w light is jam-packed with LEDs; it has 128 red lights, 32 blue lights, and 32 warm white lights! It is by far the strongest light in our Tiny Space category.

Because of its thin design, the placement possibilities are endless with this light. All you need is some mounting tape and you can set this light wherever you need: counters, closets, cabinets, etc.

2nd Place
AmazingCATS 18w Gooseneck LED Grow Lamp

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Power: 18 watts
Warranty: Unknown
Spectrum: Full Spectrum
Weight: 1.14 pounds
Lifespan: 50,000 hours

This category is for people who are really bucking tradition with their grow space. These dual headed lamps won’t take you from seed to harvest like most of our others, but they will help you get started on an awesome grow!

You can clip this light onto any table or surface up to 2.5 inches thick and it’s ready to go. The dual gooseneck bands allow you to focus all 18w over one seedling or split them outward to light 2 plants.

This light also features a cool timer feature, which can be set to 3, 6, or 12 hours, which is perfect. Seedlings and vegetative plants need between 16 and 24 hours of light per day, so you can adjust your timer according to your preferences!

This is a full spectrum light, which means it can technically work for both cycles of cannabis growth. In reality, this light will probably be sufficient for the first few weeks of veg before it will be too small to feed your growing plant.

This lamp is best for growers who want to utilize a workspace for growing. Simply clip the light to your desk and plug the USB adapter into your laptop.

Just like that, you can enjoy watching your seedling sprout while you’re working!

3rd Place
TaoTronics 12w Single Grow Bulb

Check latest price on Amazon

Veg Area Coverage: 16.8″ x 16.8″ at 20 inches
Flower Area Coverage: 
NA
Power: 
12w
Dimensions: 5.9″ x 5″ x 5″
Warranty: 12 months warranty + 6 months extended after registration
Spectrum: Red/Blue
Weight: 8.3 ounces
Lifespan: 50,000 hours
Best for: Veg only!

The third-place winner in this category is this cute, single-bulb light from TaoTronic. This light is the only one in our list that fits into a standard light socket, which makes it a versatile choice for new growers.

We love how many different ways there are to set up this light. For just a few dollars you can buy a hanging light cord and hang this light about 12” about your plant (perfect for a closet set up), or you can get a clamp with an aluminum reflector for a little more stability.

Want a boost to your veg growth? You can also buy the upgraded, full spectrum version of this light for just a bit more money!

Check out our full review of the TaoTronics 12w LED here!

Questions? If you’re considering buying one of these grow lights and have a question, ask us in the comments below and we’ll happily answer.

 

How to choose the best grow light for your project.

Choosing the best grow light for your project can be frustrating. The best light depends on several factors such as the size of your grow space, the stage of your plants’ life cycle, and your budget.

To ensure you pick the right light for your grow space, here are some key things to keep in mind:

The size of your grow space

There’s no point picking a highly rated light if it won’t fit your grow space.

If you haven’t done so already, measure the dimensions of your space (length, width, and height). Knowing these measurements will help you figure out the size and power of the grow light you require ( see next step ), as well as how many you’ll need to cover your space.

Important: If you have more than one plant, it’s important not to place them too close to each other. For optimum yields, it’s recommended that you leave a couple of inches “air space” between the plants. This will give them the space they need to grow.

Most of the lights on our list can be placed side by side or “daisy chained” together to cover larger grow areas.

The watts per sq/ft you require

Measuring wattage is one way to ensure that your light is strong enough for your grow space.

While it won’t give you a precise measurement of the actual light your plants are consuming (you need PAR for that, which we discuss at the end of this article), it will give you a good idea of the power you require for a good yield.

If you’re using an LED grow light, we recommend at least 50w per sq ft of grow space while flowering. For the vegetative stage, you’ll need around half of that.

Find out how much power you need.

First, multiply the length and width of your grow space. Then, take this value and times it by 50. That’s the minimum number of watts your grow space requires for optimal results.

Example: If your grow space 3 ft long and 3t wide, you would have a grow space area of 9 sq ft. Multiply 9 x 50 and you have 450. In this example you would want to purchase a grow light that produces at least 450 watts.

Of course, it is possible to grow cannabis with less than 50 watts per sq meter. However, you want your plants to produce awesome, potent buds. 50w per sq meter will help max out the photosynthesis process.

Color spectrum

Although your plants would probably start growing if you hung a desk lamp over them, you’ll get the best results with a grow light that produces the same full spectrum of wavelengths as the sun does.

We recommend a full spectrum LED grow light for this task.

A full spectrum LED grow light will emit the full range of wavelengths that your plants need during their lifecycle. They’ll emit blue and white spectrums for the vegetation stage and various red spectrums for flowering. They also produce UV and Infrared light which are proven to penetrate and supercharge your crop, improving the size of your buds and the levels of THC

Your budget

When calculating your budget, it’s vital that you also consider your lights energy consumption.

The average cost of electricity in the USA is 12 cents per hour. Your grow light will be running for 10-18 hours per day for between 2-6 months. If you are running an HID light that consumes 10000w, that’s at least $64 every month added to your electricity bill.

That’s a lot of energy!

Therefore, It’s important that you pick an energy efficient grow light. Again, we recommend that beginner to intermediate growers use LED lights. They may be a little more expensive up front, but the savings in terms of energy bills will be huge.

We know that our readers will have very different budgets so in this guide we have provided you with the best grow light options for each budget.

Warranty

I don’t know about you, but I always like to have a warranty and a good return policy when I’m purchasing anything electrical. It may sound obvious, but make sure you pick a grow light with a good warranty. It’ll give you peace of mind that if anything goes wrong, you can return of replace it.

We have provided warranty details for each grow light reviewed in this guide.

Brand Reputation

If you’re trying to decide between two grow lights that are the same price and have the same features, it’s always best to go with the trusted brand. There are a lot of grow light brands these days and many of them sell poorly designed lights and make outrageously false claims about what the light can do.

Before buying, it’s important to look into the brand you’re buying from. Look at their website, Amazon reviews and whether customers have had any issues.

All of the grow lights that we have featured in this guide are from trusted brands that have good reputations.

The different types of grow light for cannabis

There are three main contenders to choose from when it comes to indoor grow lights for cannabis.

1. Fluorescent (CFL) Grow Lights

Fluorescent lights come in all shapes and sizes, from twisty bulbs to long strips. They are very common and sold in most home improvement shops.

Pros of using fluorescent grow lights:

  • Cheap to purchase
  • Available in many hardware shops so very accessible
  • Most have standard light sockets, so they will fit most light fixtures.
  • Suitable for beginners with small grows ( one plant ) who just want to get their feet wet.

Cons of using fluorescent grow lights:

  • The light that CFL bulbs produce is weak compared to the other types of grow light available.
  • You have to hang them very close to your plant if you want them to get enough light to grow.
  • You’ll also have to purchase multiple bulbs if you want to cover more than just one plant

2. HID (MH & HPS) grow lights

HID grow lights have been the major player in cannabis cultivation for a long time. Many experienced and commercial growers use these lights as they believe they give them optimum yields.

The are two types of HID light. MH (Metal Halide) is a cooler light on the blue end of the spectrum that is perfect for the vegetative stage, and HPS (High Pressure Sodium), a warm, reddish light which is better for the flowering stage of your plants’ life.

If using HID, you will need to utilize a combination of MH and HPS lights.

Pros of using HID grow lights:

  • HID lights a relatively cheap to purchase compared to LED lights
  • They are fairly easy to set up
  • You can achieve excellent results using these lights.

Cons of using HID grow lights:

  • These lights produce a lot of heat, which means that you will need to invest in a cooling or ventilation system.
  • Because they expend a lot of energy (heat and cooling) they will significantly increase your energy bills.
  • They are a fire hazard if not set up and maintained properly.

3. LED Grow Lights


Many serious growers used to dismiss LED completely. However, over the past few years, advances in LED technology has led to these lights becoming the complete solution for even the most demanding grow setup.

Pros of using LED grow lights:

  • They produce way more light relative to their running cost than HID or Fluorescent lights. That means better, bigger yields and smaller energy bills.
  • Higher PAR (see our section on PAR at the end of the article).
  • They produce much less heat than HID lighting, meaning it’s easier to control the heat in your grow space (no need to purchase fans).
  • Most LED lights can plug into a standard wall socket
  • LEDs have a far greater lifespan than traditional bulbs.
  • Most have full spectrum of the sun and can be adjusted for each stage of your plants’ growth – no need to purchase different bulbs for different stages.
  • Safer to operate.
  • More environmentally friendly than other types of light.

Cons of using LED grow lights:

  • LED lights are a little more expensive to purchase than HID or Fluorescent lights. However, the initial cost is paid back in the form of reduced energy bi

We’re huge fans of LED grow lights here at GreenBudGuru. As you can see from the pros and cons of the different types of grow light above, it makes sense to invest in an LED grow light if you’re serious about growing high-quality bud effectively and efficiently.

That’s why every grow light we are recommending in this article is an LED!

Complete your grow setup

Now that you have your lights all figured out, here’s a quick list everything you need to complete the perfect grow room setup.

  • Grow room sunglasses – Most of the lights on our list use UV rays which are extremely bad for your eyes. Protect them with a decent set of grow room sunglasses.We recommend these, from Apollo Horticulture.
  • Light meter – Your plants need just the right amount of light to achieve maximum yields and potency.Invest in a light meter so that you can ensure your lights are hung at the correct distance during each phase of your plants’ life cycle. We recommend this one from Dr Meter.
  • Grow Tent – Even if you’re currently growing in a closed space, it’s a smart idea to invest in a grow tent to better control heat and be more energy efficient. This will likely be the most expensive part of your setup.They also reduce the smell from your crop and help protect it from insect infestations. We recommend the VIVOSUN line of tents, which come in 4’ x 2’ or a larger 4’ x 4’.
  • Grow Tent Kit – Every tent setup needs a few key pieces. The tent, which we already mentioned, along with a fan, a CO2 filter, and some ducting to circulate the air. We recommend buying these in a bundle to save some money.
  • Nutrients – supercharge your crop with some high-quality nutrients. Adding the right nutrients to your crop will not only improve your yield but the flavor, too.We recommend this popular trio from Fox Farm, which has everything you need from seed to harvest!

Grow Light FAQs

We’ve taken some of our readers most commonly asked questions when buying a grow light and added them below. Let us know if you have any other questions in the comments below!

How far should my light be from the plants?

Unfortunately, there is no simple answer to this question. Most grow lights come with recommended guidelines, but your needs may vary from setup to set up (and even sometimes from plant to plant).

As a general guideline, you should start with the guidelines suggested by your manufacturer, usually 18” to 24” away from the plant. Then, keep a close eye on your plants for signs that the light is too close or too far away.

A plant that is too close to the light will experience light burn, which you’ll notice by the bleaching or yellowing of the leaves and curling/drying of the tips, especially on the top leaves nearest the light ( see image below ). If you see this, it’s a sign that your light is getting too much light. Inch your grow light back until you see an improvement.

(Note the discoloration and dry, brittle tips on the top leaves of this plant, which was too close to the light.

Moving this plant away from the light about 6” or so is all you’d need to do to fix this issue.)

Alternatively, if you notice that the stem of your plant is stretching and looks like it can’t support itself, it’s too far from the light source. Move your light a little bit closer and you should see the upward growth slow down.

(The stems on this plant are nearly too long and thin to support itself during flowering; it should be moved a little closer to the light source to stop the stretching.)

Ideally, you want your plant just outside the distance that it starts to bleach. This is the “sweet spot” for maximizing your plant’s growth.

If you’re looking for something a little more scientific than the eyeball method, you can really maximize your plants’ potential by knowing the PAR Output of your light. By learning this mathematical formula, you can ensure that your plants are eating the perfect amount of delicious, full spectrum light.

What is PAR output?

PAR stands for Photosynthetically Active Radiation, which is a fancy name for the actual light your plant absorbs. Just like the human eye does not process every color on the light spectrum, our plants consume certain light wavelengths better than others.

We know that our plants like blue lights and red lights most of all on the color spectrum, but PAR takes this to the next level by considering the intensity of these light waves.

PAR is measured in the following two ways:

  • PPF = Photosynthetic Photon Flux. This measures the light’s intensity by determining how many photons per second are emitted from the light. This is measured as micromoles per second (μmol/s).
  • PPFD = Photosynthetic Photon Flux Density. This measurement is even more important because it considers both the intensity of the light and the amount of that light that actually reaches the plant. It is measured as micromoles per square foot per second (μmol/m²/s).

Some manufacturers will only provide PPF measurements, or they will provide a single PPFD measurement from the center point of the light. Both of these are tactics used by lower-quality manufacturers to manipulate their lights to look better than they really are.

To get a full understanding of your light’s PAR, look for detailed diagrams that show the PPFD at various heights or distances.

For instance, take a look at this diagram of the PAR Output for our Overall Grow Light winner; notice how it shows the full PPFD at various distances from the center of the light. It shows the PPFD of the light when it is hung 24” above the plant and how the light dispurses over 45 inches of growing space.

A plant in the center of this light will receive a PAR Output of roughly 530, but a plant two feet to the left will only get about 300 PPFD. With this information, you can choose how many lights you will need to ensure a high enough PPFD throughout your grow space.

What is a good PAR output?

Your plants require a lower PAR output during the vegetative stage and a higher PAR output during the flowering stage; this is because flowering plants are using more energy and therefore need more food.

As a general rule of thumb, here are the PAR levels you should consider for each growth stage:

  • 200-400 for new seeds or clones and parent plants.
  • 400-600 for plants in the vegetative stage.
  • 600-900 for plants in the flowering stage.

Keep in mind is that your grow space setup can have a big effect on your PAR output. Investing in a good quality grow tent with reflective mylar lining will increase your overall PAR Output by up to 35%!

Another way to increase your tent’s total PPFD is to daisy-chaining multiple lights together in the same tent.

Final thoughts

We hope that this article has been helpful as you prepare for your first grow! Sometimes growing can feel like an overwhelming adventure, but we at
GreenBudGuruare here to help make the ride a little less bumpy!

Make sure you drop your comments, questions, and pics of your grow lights to the comments! And if you enjoyed what you read, we’d really love if you gave this article a share!


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