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LED Lights for Cannabis: 3 Types & 4 Mistakes You Should Avoid When Using LEDs

July 15, 2021

Are you a beginner cultivator looking to find out how to grow cannabis with LED lights? Or a seasoned grower looking for a more efficient lighting setup for your weed crops? What are the best LED lights for cannabis on the market now, and how do they compare with other systems? What are the common mistakes that can occur when using LEDs? 

To discover the answers to all these questions and more, continue reading. You’ll be amazed to find out how LED technology has evolved to benefit your marijuana cultivation today.  

Are LED lights a good choice for growing cannabis?

If you don’t want to deal with the inconveniences of constructing ducts or exhaust systems, then LED lights are a great choice for you. You can customize and choose the spectrum of light you want with LEDs.

All you need to do is survey your surroundings and do a little research to determine what kind of setup you wish to have. 

Spider Farmer SF 4000 LED Light
LED Grow Lights

Of course, you’ll have to maintain your weed crops and supply them with all the nutes, fertilizer, and water they’ll need. LED lights for cannabis will mimic the sun and provide your marijuana plants with a source of light without excessive heat.

LED lights are an ideal choice for beginner cultivators, as they are efficient, affordable, and easy to manage. Expert cultivators accustomed to other lighting systems may find switching to LEDs a little more tricky.

But, as the benefits of growing cannabis with LED lights surface, they’ll soon realize they made the right choice.

Benefits of using LED grow lights

LEDs are very beneficial for weed cultivators. They are kind to your pocket, don’t cause harm to our planet, and can help produce substantial yields. Below are the advantages of using LED lights for growing cannabis:

  • Cost-effective: LED technology is now more widespread and available, which means it’s more affordable. You’ll also see a reduction in your energy bills as LEDs are more efficient and use less electricity.
  • Less heat: LED lights emit less heat than most other light setups. Indoor cultivators will benefit from LEDs and won’t have to endure uncomfortable heat levels in their homes.
  • Better for the environment: LED lights use less electricity compared to other lighting systems. LED setups significantly reduce your carbon footprint on the planet, and they are a cleaner energy source for the environment. 
  • Great yields: LED lights can produce greater yields in your marijuana plants in cooler conditions. LED lights that contain UV can increase the potency and resin of your weed crops. 
Cannabis flower under grow lights
Cannabis flower under grow lights

Types of LED grow lights

We’re now going to look at the best LED grow lights for cannabis available to buy on the market.

1. LED light spread

LED light spreads have a substantial amount of LEDs on their board or panel. The two main types available are the quantum board and the spider-style LED.

Quantum board

Quantum boards contain low wattage diodes spread out over a board or a large area. Cultivators use them as they produce great growth results and yields. They’re also suitable for commercial growing and can cover large setups. 

Spider LED

Spider LEDs are smaller than quantum boards, but their panels stretch out with spider-like arms containing LEDs. They are incredibly energy efficient but are among the most expensive LED types to buy.

Many cannabis enthusiasts agree that spider LEDs produce the best results out of all LED lights.  

2. Traditional LED panel

Traditional LED panels are compact lamps that are still widely used by weed cultivators today. They contain wattage diodes from small to medium, and some panels are like a mixture of COB and quantum boards in one.

The combination of red and blue LEDs emit a purple color. Cannabis growers use them as they are affordable and readily available to buy online

3. Chip on Board (COB)

COBs are an energy-efficient light source and contain hundreds of miniature LEDs on a single chip. They emit an intense white illumination, almost close to the natural light spectrum of our glowing sun.

COBs penetrate directly through your weed canopy. They also optimize your cannabis plant’s growth and yields.   

Growing cannabis with LED lights: stages of the plants

The three main stages of a weed plant’s life are seedling, vegetation, and flowering. We’ll now take a closer look at these three phases to determine the impact that cannabis LED grow lights will have on them. 

The recommended distances from the canopy to the lights fixtures are general, and you should read your LED instructions to ensure you correctly position your plants from your lights. 


Remember, cannabis seedlings are vulnerable and will require less light intensity. Too much light can dry out the soil, so you should place your LEDs higher up and further away during this phase.

Always read the manufacturer’s guidelines to ensure you place your marijuana seeds at the correct distance.  

It can be hard to determine the exact distance, as it depends on the wattage of your LED grow lights. Cannabis seedlings will be safe between 24–36 inches from your lights as a general rule of thumb. Check out our "grow lights distance chart" report for more details.

Take a gentle approach, and when your weed plants mature, you can promote photosynthesis with more light intensity.

Cannabis Plant growing indoors in soil
Weed plant growing indoors under LED lights


Your weed plants will need more light for photosynthesis during this stage, so place your LEDs closer. The tops of your cannabis crops should be between 12–24 inches from your LED source. If you can’t adjust the height, you should modify the light intensity.

As your weed plants grow, they’ll become less demanding on light intensity. If you don’t have full-spectrum LED lights for cannabis, blue LED lights are ideal for vegging. Blue LEDs promote healthy and sturdy leaves and stems.


When your marijuana crops have completed the vegging stage, it’s now time for them to bloom. Place your LED lights between 16–36 inches from the canopy of your cannabis plants to maximize photosynthesis.

Be careful of placing your LED lights for cannabis too near, as this can damage weed crops’ growth. 

Red LEDs are perfect for your marijuana plants’ flowering stage to promote bud development and stem acceleration. They also contribute to potency and resin production for a healthy yield.

Ensure you watch the distance carefully and raise your LED lights away from your weed canopy as they grow. 

Mistakes to avoid when growing cannabis with LED lights

LED lights for cannabis are an exciting new technology, and cultivators may find it tempting to set them up straight away. Some common mistakes can occur for beginner and veteran growers that could hinder your marijuana crops.

We’ll now look at four mistakes to avoid when you make the switch to LED lights for cultivating weed.

1. Overwatering

Overwatering can be a problem, especially for veteran growers who’ve used high-intensity discharge lights (HID) in the past. LED lights emit less heat than most other lighting systems like HID, and seasoned cultivators may forget this.

Cannabis LED grow lights won’t dry out the soil in your weed pots, unlike most other lighting setups. 

Too much water may cause deprivation of oxygen to your precious weed crop. Your cannabis plants may droop down, their leaves can turn yellow, and it can lead to other nutrient problems.

2. Buying cheap, low-quality LED lights

The widespread use of the technology means you’re guaranteed to find cheap LED lights for sale on the internet. You should remain vigilant when purchasing the lights, especially if the price is too good to be true. Search well enough and you will get really good discounts on great grow lights though.

Some manufacturers will produce LEDs in high quantities that may overlook quality. You may find wattage outputs can be lower than what’s specified on the box and may hamper your weed plant’s growth. Some LED lights for cannabis may not have passed safety tests and could potentially be an electrical hazard.  

3. Using the wrong type of LED lights

Most weed cultivators use full-spectrum LED lights for their marijuana plants’ vegetation and flowering stages. Depending on the model you buy, you’ll find that some products will have different settings to adjust the light.

LED lights for cannabis are also available to buy for single cannabis plant phases. Blue LED lights are ideal for your weed crops’ growth during the vegetation stages.

Red LED lights are for your marijuana plants’ bud development and flowering phase. Ensure you buy the right type of LED lights for growing cannabis.

 LED cannabis room
LED Cannabis Room

4. Wrong distance

Another mistake that veteran cultivators make when they switch to LED lights for cannabis is the wrong distance. If you’re used to HID setups, you may end up placing your new LED lights at a distance that can stress your cannabis plants.

Because LEDs emit less heat, you may end up placing them too far away from your weed crops. Far distance may cause your marijuana plants to stretch to reach the light. Placing your cannabis crops too near the LEDs may cause brownness, drying, and bleaching of the leaves.

High-quality LEDs come equipped with heat sinks, which allow for the dissipation of unwanted heat. Nonetheless, you should maintain a distance of 30 to 45 cm (12 to 18 inches) between the lights and the plant canopy.

A light burn can occur if the plants are too close to the LEDs. Should this happen, you would see leaves turning yellow or brown, with the edges curled up. If left unchecked, the leaves eventually become crispy and brittle.

Light burn affects the plant's normal photosynthetic process because the leaves can't do their work. Hence, you should do your utmost best to keep the leaves healthy.

The easiest way to check if your lights are too close is to stick your hand under them. If it is too hot for you, then it is also too hot for the plants. Adjust the placement of the lights until the temperature feels comfortable.

You should also check if all parts of the plants are getting sufficient light. The primary lens of an LED directs light at a 160- or 180-degree angle. You might have to purchase a secondary 90- or 120-degree lens to refocus light.

Each extra lens, however, reduces the output intensity by 8 to 10%. Furthermore, it would be best to cover all interior walls with aluminum foil (reflector panels) to bounce light to the plants.

LED lights vs. other types

Choosing the best grow lights is one of the most important steps for any cannabis cultivator. All cannabis plants will need light to grow. Lights allow plants to perform photosynthesis and therefore feed themselves and grow.

So how do LED lights for cannabis compare to other light sources? Here are the main differences between LEDs and other types of lighting systems.

  • LED vs. HPS: Larger HPS generally requires a ballast, whereas LED lights simply plug and play.
  • LED vs. CFLs: LEDs are more efficient and require less wattage than CFL bulbs.
  • LED vs. MH: Metal halide (MH) lights require more maintenance than LEDs. Although MH HPS grow lights produce high-quality lighting, they’re much more expensive to run.
  • LED vs. T5: LEDs are more efficient and have a longer lifespan than fluorescent T5 grow lights.
Cannabis Plant Under LED Lights
Cannabis Plant Under LED Lights

FAQs about LED lights for cannabis

What are the best LED grow lights for cannabis?

Cannabis users love full-spectrum LED growth lights, and traditional LED panels are still popular among cultivators today. Determine your budget and surroundings to choose the best type for you.

How far should LED lights be from cannabis?

Depending on the wattage, the general distance is 24–36 inches for seeding, 12–24 inches for vegging, and 16–36 inches for flowering.

Why do cannabis growers not like LED lights?

LED lights for cannabis can be difficult and expensive to repair or replace if one of the lights stops working.

How many watts are needed to flower cannabis with LED lights?

Although it may sound complicated, finding out the size of the LED lights you will need for your grow room is actually very straightforward. Just refer to the table below.

Number of Plants Area in Square Feet Recommended Wattage
1 1 32
2 2 64
4 4 128
6 6 192
8 8 256
10 10 320

Allow 1 square foot of space for each marijuana plant so that it can spread out and grow. The recommended wattage is what is required by the plants during their flowering stage.

Flowering cannabis consumes significantly more power than the other growth stages, so it is used here as the base point. During the periods when your plants don't need a lot of light intensity, it's easy to switch off or dim the lights, but it's not so easy to adjust when you need more.

If the recommended wattage seems low, remember that LEDs can be much brighter than other grow lights. To illustrate, a typical HID light draws 45 watts of power to provide lighting per square foot. In comparison, LEDs only need 32 watts to produce the same light intensity.

How much can I yield from indoor cannabis plants using LED lights?

LED lights help promote significant yields during the flowering phase. Yields will depend on the weed strain you’ve cultivated.

How good are LED lights for a small beginner growing cannabis?

LED lights are ideal for beginners as expert cultivators would be used to other lighting systems, and old habits can be hard to shake off.

LEDs — make the switch

LED lights are currently the future and one of the most efficient lighting sources for your cannabis plants. This technology can help your weed crops thrive and produce big, healthy yields. It can be hard to switch from a different lighting source, but it’ll be worth it in the long run.

Energy-saving, friendly for our environment, and affordable. LED lights for cannabis are a game-changer, and once you get the hang of it, you won’t look back.

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