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Quantum Board Vs COB LED Grow Lights

by February 27, 2018

When you walk into the grow lights industry, you come to see that initially, the COBs were ruling the light industry. Afterward, the quantum boards took the lead.

Does that mean that QBs are better? An improvement on COBs?

Not necessarily.

Both are great lights for plants and each has its advantages and disadvantages.

We’ll take a look at those pros and cons, and help you figure out which one is right for you.

What is a COB?

COB LED Grow Light

A COB is known as the Chip on Board appears to the scene when thousands of lumens are required from a single source. A COB led array involves multiple chips mounted on a single common board made up of sapphire or silicon carbide as compared to the multiple chip configuration. COB technology mounts several thousand LED chips within a single metal or ceramic-based board. This innovation allows you to have greater packaging densities of the LED array. Some other advantages of COB lights include low energy consumption, constant uniform light output, and minimal footprints. The COB lights arrangement comprises two contacts and only one circuit.

Advantages of a COB light

If you are looking for the COB light dominance, you can have a look at these listed points:

  • The size of a COB LED light is best for growing indoor plants.
  • The uniformity between the LED arrays performs well for close distance.
  • The arrangement of one circuit and two contacts makes the design easy.
  • By providing constant light output, less energy is consumed.

Disadvantages of a COB light

Some drawbacks of using COB lights are also mentioned here:

  • COB LED lights are more expensive and are smaller in size as compared to the quantum Board light.
  • These lights have a low bright spectrum as compared to the quantum Board light.
  • COB lights are not preferable when it comes to energy consumption.
    These LED lights are more technical and require high maintenance costs.

What is a Quantum Board?

100w quantum board grow lamp

A quantum board is a large circuit board that mounts several hundred mid-power LEDs. These LEDs are connected in series with each other to form an intelligent spectrum string. Later, these strings are connected in parallel to drive high voltage and current operations. These boards are an alternative to the COB led grow lights. Quantum boards use less power consumption and span a greater area to cover the cost of additional larger heat sinks.

Advantages of a Quantum Board

A benefit of Quantum board over the COB light is the simple thermal management.

  • Quantum board lights have light uniformity and a greater light spread.
  • Quantum board lights consume less energy. They consume 50 watts for 180+ lumens, while on the other hand, COB lights consume 50 watts for 160-170 lumens.

Disadvantages of a Quantum Board

Quantum board lights are not 100% efficient. Some downsides of using these lights are listed below:

  • You cannot create the quantum boards on your own. However, you can easily build COBs.
  • Usually, quantum board lights are out of stock.
  • Quantum board lights do not provide uniform light, hence some parts receive a low intensity of light.

Similarities Between COBs And Quantum Boards

There is a reason these two types of lighting both had a revolutionary impact on the industry. They have several similarities and they are exactly the things that make them so appealing to indoor cannabis growers.

Same Principle

The main similarity is that both essentially use the same principle. It is simply the scale that differs.

A COB is made up of many tiny LED diodes tightly packed onto a single chip to produce a single, powerful beam of light. A quantum board also has many LEDs on it, but those LEDs are more powerful and more spaced out. Essentially, a quantum board is simply a very large COB.

Same Spectrum

The other major similarity is the color spectrum. Both COBs and quantum boards use full-spectrum white LED diodes.

They are available in various different color temperatures, from warm 3000K light to cool 7000K light. The most common color temperatures are 3000K, 3500K, 5000K, and 6000K.

The warmer white light (3000K to 4000K) contains more red wavelength light, making it better for flowering, while the cooler light (5000K to 7000K) contains more blue and is thus better for vegging.

While “blurple” lights dominated in the past, the industry is coming to realize that white light is actually better for plants. That realization came about thanks to the popularity of COBs and quantum boards.

But it is true that plants especially like red light (and blue as well), so many quantum and COB LED fixtures now have supplementary diodes that add a bit of red, and sometimes UV, IR, or blue as well.

DIY Setups

Both quantum boards and COBs are great for building your own lighting system. Several manufacturers of each even offer DIY kits that include all the components you need. All you have to do is put it all together. Alternatively, you can save even more and do it completely on your own, without the use of a kit.

Differences Between COBs And Quantum Boards

As both COBs and quantum boards use LEDs but they both vary in the white color spectrum scale. Some other differences are as follows:

Coverage area

The first major difference is in the way the light fills the coverage area. A COB light has a single source of light, hence the light does not reach the outside area completely as compared to the middle section. On the other hand, a quantum board comprises diodes that cover the complete area uniformly. It does not cover the center part only. The result is a much more even light spread for quantum boards. COBs give you a ton of intensity in the middle of the coverage area, but it drops off more toward the outside than a quantum board light.

Penetration&Intensity of Light

This is the flip side of the previous difference. As COB has strong light emission, it penetrates deeply below the canopy, especially in the middle part. Toward the outside, that penetration power diminishes considerably. Quantum boards get great penetration, too, just not as good as a COB (in the middle anyway).

Heat Management

Because COBs are such a powerful source of light, with many tiny diodes crammed onto a small surface area, they naturally emit a lot of heat. Single COBs can be cooled by heat sinks alone, but fixtures with multiple COBs need to have fans.

Quantum boards are always passively cooled. Usually, this is done with a simple aluminum board, but sometimes a heatsink is used instead.

The fixtures as a whole still emit about the same amount of heat as other LED fixtures, including COBs, but because the individual diodes are spread out, passive cooling is enough to keep them from overheating.

Should I Get A COB Or A Quantum Board?

When it comes to COB Vs Quantum Board, you must review the above-stated factors. Quantum boards are highly recommended for grow lights. Quantum boards are the best option if you have limited space and require a greater light spread.

Are LED grow lights harmful to our eyes?

by February 27, 2018

There is no question that any grow light can cause harm to your plants if used improperly. As a grower, you’ve likely put a lot of thought into details like hanging distance, supplemental cooling, and hydration, all to be certain your lights are helping your plants thrive, rather than damaging them or wearing them down.

But what about humans? Whether you have a small home grow or run a large commercial operation, it’s important to understand how your lights could pose certain risks to you or your employees. The LED lights are very concentrated and can damage your eyes. This is truer than ever with today’s high power LEDs. Never look directly into LEDs and wear sunglasses.

The bottom line is that LED grow lights are no more dangerous than any other type of grow light.  HPS is much more dangerous than LEDs – high heat and risk of burns, risk of broken bulbs and fires, high environmental damage due to mercury content, high carbon footprint. This has been studied and proven by CELMA, the Federation of National Manufacturers Association for Luminaires and Electrotechnical Components for Luminaires in the European Union.

However, as with any grow light, it’s important to understand what health risks do come with using LED grow lights so you can protect yourself accordingly. With the proper precautions, you have nothing to worry about.

Do LED grow lights contain hazardous materials?

One common LED myth is that these grow lights contain dangerous heavy metals such as mercury. While this is incorrect, it is a myth based on a former truth.  

With the advancement of LED technology, neither of these things are true today. Nowadays, diodes emit light directly and they don’t contain mercury. Nothing to worry about.

Are led grow lights harmful to human eyes?

led grow light eyes

There are several factors that affect the safety of any grow lights: intensity, wavelength and duration. Intense lights will always damage your eyes, regardless of what wavelength that the lights release and the duration. Intense lights can cause burns on the skin, and a “sunburn” on the retinas will interfere with your ability to see.

A good example would be staring at the bright light in your lamp. A brief glance may cause odd patterns in your vision as you blink. Stare for a long time, and it could damage your eyes. The same is true of any bright light, LED or conventional. At the same time, very bright lights too close to the plants could “sunburn” them, too. Have the lights at the right distance from the plants to avoid this.

Most wavelengths are not harmful. However, LED grow lights that put out ultraviolet light are harmful to your eyes. This includes but isn’t limited to fluorescent LED grow lights, HPS grow lights and metal halide grow lights. Any blue light could emit ultraviolet light. You can tell if the UV output is high if you’re getting a tan while working under your grow lights. On the flipside, pure red lights aren’t harmful unless at a very high intensity.

One way to protect yourself is to minimize the time spent under LED grow lights. Another is to wear protective glasses when under the lights or working around them. Yet another layer of protection is to keep the grow lights inside of grow tents that seal in the light.

If you want to safe from led grow light you need to use best led grow lights.

LED Grow Light Safety

Fortunately, prevention of all these potential injuries is fairly simple. You don’t have to choose between the benefits of LED grow lights and your own safety. You just have to follow a few precautions.

  1. Wear protective glasses designed for use with LED lights. Sunglasses will protect your eyes from harmful rays, but they’ll give you a discolored view of your crop, making it harder to detect problems. Grow glasses allow you to view your plants naturally.
  2. Hang lights at least 8 feet off the ground and try to keep a distance of at least 3 feet between yourself and any UV-emitting light fixture. This is often not possible in a grow tent.
  3. Wear long-sleeved shirts and work with as little skin exposed as possible.
  4. If you have employees, share these safety tips with them and put up signs to warn of UVA and UVB exposure.
  5. Use an LED grow light with a view mode in natural white.

You put a lot of thought into creating a grow system that’s safe and healthy for your plants. Do the same for yourself. 

And don’t hesitate to seek out your light manufacturer’s guidance and input on risks associated with your LED grow lights. At Seedz Lighting, we’re always eager to help growers ensure the safest operation possible. If you have any questions about our lights, please reach out.

Should I Leave Grow Lights On 24 Hours A Day?

by February 27, 2018

Providing sufficient light to your plants inside a grow space can be tricky, but using Grow lights enables your plants to thrive indoors and extend your growing season.

Plant grow lights are a great tool to make your growing process more efficient, but they can also be harmful to the plant if don’t follow the proper lighting schedule.

Now you might be wondering – how long should you keep grow lights on or if it is recommended to leave grow lights on for 24 hours?

The answer to the question is no, it is not recommended to leave your grow light 24 hours a day, because this will force plants to grow quickly. It is ideal to keep a grow light on for about 12 to 18 hours.

Too much light in various growth phases can interrupt a weed plant’s natural process of growth and dormancy. Worse, light exposure for a whole day can damage and kill your plants.

What Happens If I Accidentally Leave the Grow Lights on for 24 Hours?

24hours grow light

One of the most often asked question from new growers is from those who accidentally leave their grow lights on for more than 24 hours. Leaving the lights on for too long is actually a common problem.

It’s often due to a malfunction in the timer, the timer breaking, or forgetting to shut the timer off manually.

If the plants are in the vegetative phase, generally it is not an issue if they are overexposed light. Nonetheless, 24 hours of light is really not good for production.

However, overexposure to light will not kill your plants.

Some growers believe that seedlings need 24 hours of light. But in actuality, many experts recommend that you give seedlings 12 hours of light and 12 hours of dark.

On the other hand, some specialist feels that your seedlings need 16 hours of light, depending on the variety.

Length Of The Light-Dark Cycle And Plant Growth

There are basically four growth cycles of a cannabis plant. Each growth cycle requires a certain amount of light and dark for optimum plant growth and higher yields.

  • Germination – cannabis seeds do not need light to germinate. In fact, they require complete darkness for successful germination.
  • Seedling – once the seeds have sprouted, the seedling will need a lot of light. Seedlings need 18 to 24 hours of light, depending on preference and the strain.
  • Vegetative stage – Indoor growers typically give their plants either 18 hours of light and 6 hours of dark each day or 24 hours of light with no darkness.
  • Flowering stage – the flowering stage generally requires 10 to 12 hour light/dark cycle.

In addition, cannabis does not respond well to extreme temperatures. For the best growth, avoid colder temperatures. During the vegetative stage keep temperatures in your grow tent between 68°F to 86°F (20-30°C).

During the flowering stage, ideal temperatures should be between 68°F to 77°F (20-25°C). Likewise, perfect humidity levels should stay between 40% to 60% humidity.

Should Autoflowers Have 24 Hours of Light?

autoflower canabis

Autoflowering marijuana plants need time to rest, just like any other plant. The main difference with auto-flowering cannabis strains is that they switch to flowering automatically. They do not need you to shorten the daylight hours to tell them when to switch.

Theoretically, you could run the lights 24/7 even during flowering, but you shouldn’t. However, you can run them on an 18/6, or even a 20/4, cycle during the bloom stage, the same as during vegging.

Should Seedlings Get 24 Hours Of Light?

No, they should not. Seedlings also need a dark period. We recommend leaving the lights on for 12 to 16 hours a day for seedlings, with our preference being 16 over 12.

Why do People Leave Grow Lights on for 24 Hours?

For most growers, their main objective is production and yield. It stands to reason that the more light a plant gets, the more it produces. With this in mind, some growers leave their lights on 24/7.

Although it is true that more light will produce more yields, it’s the type of light that needs to be monitored. For the most part, the strength of a grow light and the amount of light given to a plant will produce better yields.

If your plants have stunted growth, it is usually best to upgrade the type of grow light you are using instead of increasing the number of light hours. Generally, you need to buy a stronger grow light that has good light intensity.

The Best Lighting Schedules For Cannabis

grow lights for cannabis

We’ll start with flowering because there is no flexibility to increase the daylight hours during this stage. Your lights need to be off for 12 hours per day (with the exception of autoflowers, of course). Keeping them on longer can result in your weed plants switching back to vegging and then you’ll have a hard time getting them to flower again.

During vegging, you have much more flexibility. It is perfectly possible to leave the lights on overnight, but as mentioned, it is best to give your plants at least some darkness.

The most common lighting schedule during vegging is 18 hours of light and 6 hours of darkness. This is the schedule we recommend. 20 hours on and 4 hours off works well, too.

Another interesting option is to use a 6/2 light schedule. What this means is you leave the lights on for six hours, then turn them off for two. You have 3 of these cycles per day. You still end up with 18 hours of daylight and 6 hours of darkness, but they do not all fall at once.

Leave Grow Lights On 24/7: Final Thoughts

Yes, you can leave grow lights on 24/7. Typically this is done during the vegetative stage of growth.

Moreover, your plants will grow rather big and have a lot of foliage plus stem height.

Nevertheless, most plants including cannabis will greatly benefit from a light and dark cycle. In fact, your plants will be a lot healthier and robust.

Likewise, during the flowering stage, cannabis requires12 hours of light and 12 hours of dark to produce good buds. Quite frankly, the most potent and large buds come from plants that have a balanced amount of light and dark.

Overall, 24/7 light can be productive during the vegetative stage of growth, just be careful not to overdo it. If your plants receive too much light during this stage, they will be prone to disease and have a lower yield.

Best Light Schedule for Autoflowers

by February 27, 2018

What is a light cycle and which one is the best for your auto-flowering plants?

Unlike photoperiods that need at least 12hrs of darkness to trigger flowering, autoflowers automatically are in the flowering cycle from the seedling stage. They start producing buds based on age thus they don’t depend on darkness to start the flowering cycle.

Tip: Light cycles are used to simulate seasons in nature, more light = summer, more darkness = winter.

1. What is the best light cycle for autoflowers?

Most growers agree that the optimum amount of light to give auto-flowering strains is somewhere between 18-24 hours of light a day. As a grower you should adjust the light depending on the cultivar you’re growing.

There are basically three life cycles aka Light schedules: 24/0, 18/6, and 12/12 (the first number is hours of light, the second is hours of dark). You can always adjust the cycle as long as they are receiving more than 12 hours of light a day (to achieve the best results). An example would be 19/5, 16/8, 22/2, etc.

Having that in mind, there are growers experimenting with schedules like 6/18 but if you’re new to growing you should stick to the basic schedules mentioned above.

2. Do autoflowers need darkness?   

There are growers who believe auto-flowering plants need a dark period and won’t be as healthy if they get a 24/0 light schedule. There’s no real evidence of that but there may be exceptions. Also have in mind that a 24/0 will lower humidity, increase temperature, and increase the light bill.

Schedules like 18/6 or 12/12 will save you electricity and if the few hours of darkness indeed help the plant to grow better, it’s a win-win. We recommend starting with an 18/6 light cycle and if you see your autoflower has the potential to grow more, you can always try again in the next cycle.

3. 24/0 Light Cycle

Plants usually grow faster when they get more light. This schedule is a good choice if you live in a cold climate, keeping the lights turned on 24hrs a day will keep your plants warm.

24/0 Light Cycle for cannabis plants

24/0 Light Cycle for cannabis plants.

Obviously, this is the easiest light cycle as you don’t even need a timer, just turn on lights until harvest.


•  Doesn’t require a timer. 

•  May result in the best yields.


•  Uses more energy, can get expensive.

4. 18/6 Light Cycle

This is the most common cycle for autoflowers. You’re providing enough light for your plants to develop and a few hours of dark for them to rest, encouraging healthy growth. This can be good in hot climates.

You can leave your lights at night and have them turn off during the 6 hottest hours of the day. By using this schedule you’ll be using around 25% less electricity, which adds up to be a good economy at the end of every harvest.

18/6 Light Cycle for cannabis plants

18/6 Light Cycle for cannabis plants.

A lot of growers who have experimented with 24/0 and 18/6 light cycles say they didn’t notice any major difference in final yield. The only minor inconvenience with this schedule is having to buy and adjust a timer. They cost around 10 bucks so it shouldn’t be a problem at all.


•  Allows your plants to rest.

•  Uses less electricity, allowing us to save on electricity.

•  Can help lower temperatures and increasing humidity in hot climates.


•  Requires a timer. This shouldn’t be a problem at all, as this is the first thing you should buy when growing indoors.

5. 12/12  light cycle

The 12/12 schedule is normally used for photoperiods. It can also be used for autoflowers but it’s not that popular. Normally growers give autoflowers this light cycle when they have them growing in the same tent as photoperiods. By giving your autos 12/12 you’re not using them to their full advantage.

12/12 Light Cycle for cannabis plants

12/12 Light Cycle for cannabis plants.

Because your plant is getting less light each day, it isn’t able to make as much energy to promote growth. It will underperform compared to the other light cycles, that being said, you can grow them just fine if you don’t mind reduced yields and an overall smaller plant. 

6. In Conclusion

There isn’t really a proven best light cycle. Before going for any light cycle, think about electricity costs and the climate you’ll be growing in. If you are in doubt, start with 18/6. This cycle is the most used and should work for all autoflowers.

When growing outdoors you have to work with what you have as you can’t control the sun (obviously). Outdoor growers should be aware that with the change of seasons the amount of daylight may increase or decrease but autoflowers should grow fine in all seasons. 

Quoted from By Enzo Schlacci

Best Light Schedule For Cannabis In The Vegetative Stage

by February 27, 2018

The amount of light cannabis receives in this stage will directly impact its health and ability to support the buds.

The vegetative stage has the ability to prepare the plant to support the bud, while also making it grow more and more healthy. Failing to provide a good amount of light will result in an unhappy plant that will be more prone to diseases and bugs.

The proper amount of light in the vegetative stage has the ability to prepare the plant to support the bud, while also making it grow more and healthier.

1. What Is The Light Cycle In Vegetative Cannabis?

Light is extremely important for plants in the vegetative phase because it’s what they use to photosynthesize and grow sturdy and healthy, so if they get more light, the more and better they grow.

Generally, the most common light cycle for the vegetative stage is 18/6 (light/darkness) but it can be any combination of light and darkness (like 20/4, 19/5, 17/7) as long as they don’t get more than 12 hours of darkness per day as this will trigger flowering.

light schedule for cannabis

Light cycles for cannabis vegetative stage.

Have in mind that giving your plants less light will cause them to develop slower and if you’re not that experienced, you should follow the 18/6 light cycle and only give them more light (like 20/4) if you know your plant can take it.

Not always giving them more light is going to result in faster or more development and you can harm or really stress your plant by doing this, making them turn into hermaphrodites or showing other heat stress symptoms.

2. Light Cycle For Vegetative Cannabis Outdoors

Photoperiodic Plants

When growing outdoors, the light cycle will solely depend on the season you’re in. Each season has a different amount of light and darkness hours, and this will hugely influence when you can start growing your photoperiodic cannabis plants.

For example, in California, we have the following light cycles throughout the year:


December (9/15)

January (10/14)

February (11/13)


March (12/12 of light)

April (13/11 of light)

May (14/10)


June (14:30/9:30)

July (14/10)

August (13/11)


September (12/12)

October (11/13)

November (10/14)

This means that when growing outdoor you have to know the amount of light and darkness you will receive in the next couple of months so your plant develops the way you want to.

Note: Have in mind the information above is exclusive to California, you should get information about how is it in your area. That information can easily be found on the internet.

lightcycle cannabis

When growing outdoors, the light cycle will solely depend on the season youre in.

Autoflowering Plants

On the other side, autoflowering plants do not have a vegetative stage and start flowering directly from seed, not depending on a light cycle to do so.

This means you can grow autoflowering strains outdoors all year long. Although the amount of light and other factors like humidity and temperature may have an influence on the development of your plant, they will definitely vegetate and develop properly outdoors at any given time, before flowering.

3. Light Cycle For Vegetative Cannabis Indoors

Photoperiodic Plants

As you may know, when growing indoors we are responsible for maintaining all the elements of the environment, in the beginning, it can be a little bit hard but when we get more experienced it can have various advantages.

Like we said above, photoperiodic cannabis depends solely on the amount of light and darkness to start flowering, which can be tricky for new growers outdoors but when growing indoors, we are in full control of everything, including the light cycle.

Unlike autoflowering cannabis, photoperiodic plants indoor can vegetate for a long time and will only flower when we change the light cycle.

This allows us to vegetate our plants as long as we want and then flip them to the flowering stage when we have met our goals in the vegetative phase.

100watt cannabis grow light

As long as you keep your plants in an 18/6 (or other combinations with no more than 12hs of darkness) they will continue to grow.

Autoflowering Plants

Autoflowering cannabis will flower independently of the amount of darkness they get. Obviously, giving them too little light like a 5/19 light cycle will make them seriously underdevelop but they will flower either less.

More experienced growers can experiment with different light cycles, some growers even saying they got the best results by giving their autoflowers 24hs of uninterrupted light. We encourage you to experiment also, but be aware that too much or too little light may stress your plants.

Different light cycles with autoflowering cannabis are also used to save electricity, by giving your plant a little bit less of light (like a 16/8) it will sum up to an important amount at the end of each cycle.

Even though it can affect the yield, removing only 2hs of light per day shouldn’t make a big difference on the plant and can save you a couple of bucks.

If you are still new to growing cannabis and want to guarantee your harvest, start with an 18/6 light cycle, and after you get a little bit of experience, it will be easier to read your plant’s signs and you can start experimenting with other light cycles.

4. In Conclusion

The vegetative stage of cannabis is super important. In this stage cannabis is building up strength to be able to support all the buds in the flowering stage. There’s nothing as the best light cycle for the vegetative stage, the light cycle will depend on a lot of factors that are individual to each grow room.

It is crucial that you give the amount of light and nutrients it needs so she can develop properly and be ready for the next stage.

Even though it mostly depends on genetics, the amount of light your plant will be able to receive is a decisive factor in the amount and quality of flowers it will produce.

If you don’t know which one to follow, we recommend providing a 18/6 light cycle for your cannabis plants in the vegetative stage as this cycle has been proved by a lot of growers to work really well, allowing the plant to develop properly.

This is awesome! We will buy more Quantum board grow lights when the time comes! Highly recommend this product!

Jane Travis


Second order, first was a 300 that’s still going strong! So far the new unit – 600 – is performing flawlessly as well.
Easy to use, no maintenance, and last for years. Awesome product.

Larry Wilson


First of all, the QB lighting is fantastic!
Customer service is great. I had a small problem and Thomas has been very helpful in resolving it.
The package arrived on time in good condition.
It’s built tough so it was a little heavier than I thought, but once it’s up and running it’s great.
Would buy it again!
Keep up the good work…

Amanda Richards


Best Light Spectrum to Grow Autoflowers

by February 27, 2018

Providing different spectrums in each stage may influence the quality of your harvest.

When growing auto-flowering plants indoors we need to simulate the environment they naturally grow in. The environment includes humidity, temperature, and the most essential of them all: light.

Either you prefer light bulbs or LEDs, you need the right spectrum in each stage for optimum growth. 

1. What is Light Spectrum?

The light spectrum is the different colors (aka wavelengths) a source of light can emit. Light is measured in nanometers (nm) and each nanometer represents a band of light (a band of light is a section in the color spectrum). Humans can see a small part of the spectrum, between 380 to 780 nanometers, which means we can only see the colors ranging from violet to red.

Even though it appears white, the sun is a full spectrum light source and contains the whole spectral wavelength. That’s why rainbows happen. When raindrops refract light into individual wavelengths you can see all the colors (visible to humans) that makeup sunlight.

visible spectrum

Humans can see only a part of the spectrum, between 380 to 780 nanometers (from violet to red).

In nature, cannabis plants grow under the sun, receiving the whole spectrum of wavelengths. This means we have to provide the maximum amount of wavelengths possible for the best development of our plant.

Although it’s not essential, it is considered good to provide the best light spectrum to encourage plant growth.

Remember this is not a rule, you can grow your plant from seed to harvest with any spectrum or amount of light but this can seriously affect your harvest.

2. Light Spectrums in Each Stage

During the vegetative stage, cannabis in the wild needs blue wavelengths to grow strong, big, and promote leaf growth. When growing indoors we aim to grow as many leaves as possible. With more leaves, there is more surface to absorb light, this way we ensure our plant develops a strong stem and branches preparing her for the flowering stage. 

When entering the flowering stage, cannabis in the wild uses red wavelengths to promote bud formation. If we want to produce dense buds and increase yields we need to provide the plant red wavelengths, this will increase the rate of photosynthesis thus increasing bud formation.

light spectrum and its benefits for cannabis growth

Light Spectrum and its benefits for Cannabis growth.

•  Tip: When experimenting with training, using “red” light will make plants grow taller, making it easier to train.

The general rules are “blue” light = shorter and stronger plants with more leaves, “red” light = taller and weaker (when compared to plants grown under “blue” lights) plants with fewer leaves.

3. Types of Light

Grow lights are usually divided into two kinds, light bulbs, and LEDs.

Light bulbs emit a limited scope of wavelengths meaning there are colors of the spectrum they don’t emit, therefore they are narrow-spectrum lights.

LEDs emit almost all the colors in the spectrum, they are composed of blue, red, and white diodes allowing them to emit all the wavelengths of the spectrum, therefore making them full-spectrum lights.

Light Bulbs: HPS, MH, CFL, and HID

Light bulbs come in four types: Metal Halide (CMH), High Pressure Sodium (HPS), Compact Fluorescent Lights (CFL) and High Intensity Discharge (HID). 

MH bulbs are rated around 6500 Kelvin and are usually used in the vegetative stage because they emit a “blue” light (aka colder light).

HPS bulbs are rated at 2000 Kelvin are usually used in the flowering stage for their “red” light (aka warmer light).

vegetative stage

Light Spectrum: use blue wavelengths for the vegetative stage, and red for the flowering stage.

CFLs are rated at around 5000 Kelvin, they emit a very weak “blue” light and are only used with seedlings and clones as they just need to develop roots for the first couple of days when the vegetative stage begins they should be transferred to a growing space with stronger lighting. 

HID can cover from 3500 to 5000 Kelvin, they are similar to HPS but contains xenon inside, thus emitting a different spectrum and are more efficient while being more compact.

differen light bulbs

Light Bulbs: HPS, MH, CFL, and HID.

•  Tip: You can also grow your plants under both CMH and HPS bulbs, this is called a mixed spectrum and will ultimately result in a better harvest.


•  Cheaper than average LED lights

•  You don’t need to change the whole fixture, just replace the bulb


•  Electricity cost is higher if compared to LEDs.

•  Need extra equipment for cooling.

•  Requires changing bulbs (CMH to HPS) when entering the flowering stage.

Full Spectrum LEDs, and Infrared and UV Lights

All LEDs are full-spectrum lights unless advised, they may not contain all wavelengths but will emit the needed amount for each stage, unlike light bulbs, you won’t have to change anything other than your timer when you’re about to enter the flowering stage.

You can find full-spectrum LEDs that have UV and infrared diodes, if not, there are LEDs designed to emit those spectrums. They’re not that common in indoor growing but are said to benefit growers.

Quatumn Board LED Grow Light 100w

LEDs – Light Emitting Diodes. Many manufacturers now produce outstanding LEDs that almost mimic the suns full spectrum.

Just like everything else on the planet, cannabis plants are damaged by too much UV light but at the right amount. It can promote trichome production as the cannabis plants produce trichomes to protect itself from too much light. 

As UV lights, infrared lights can harm your plants in excess but at the right amount, it can boost photosynthesis, affect yields, plant growth, and plant health in a positive way.


•  Used on the entire life cycle.

•  Energy-saving.

•  Longer lifetime than bulbs.


•  Higher cost.

Note: It’s unusual to have UV and Infrared lights, they’re expensive and are NOT essential for growing good flowers. They’re recommended for more experienced growers who want to experiment with different spectrums.

4. Light Spectrums for Autoflowers

As most of you already know cannabis plants have two stages: the vegetative stage, and the flowering stage, needing a different light schedule and spectrums in each one of them. 

Unlike photoperiodic, autoflowering plants start their life cycle in the flowering stage and depend solely on age to start producing buds. That’s why we recommend using a mixed spectrum of warm and cold light bulbs (CMH and HPS) or a full-spectrum LED during the whole lifecycle of your autoflower.

This way your plant will receive a complete spectrum of light guaranteeing the best flowers and biggest yield. 

5. In Conclusion

The light spectrum is a small part of a much bigger system, there’s nothing as better light for your plant. But remember, the final product does NOT depend solely on your light.

Depending on which type you choose, either an LED or bulbs, you’ll have to adjust your growing environment accordingly to guarantee the best result possible.

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