Can Grow Lights Burn Plants? | Precautions You Need to Take!

  • Home
  • Blog
  • Can Grow Lights Burn Plants? | Precautions You Need to Take!

by Morgan

Last update:

August 29, 2023

How To Choose The Right Lighting For Your Marijuana Grow Room

The effectiveness of grow lights for indoor plants will depend on the accuracy in regulating the heat. Artificial lights constitute different elements such as heat, color, and light intensity.

The lights will burn the plants if the heat intensity is too high. You should ensure you use the right number of watts and the correct distance of the bulb from the marijuana seedlings. Furthermore, you should be adequately knowledgeable about the light requirements for your plant before you buy the bulb.

So if you have been asking yourself, "Can grow lights burn plants?" you are in the right place. This article aims at equipping you with sufficient information about the precautions you should take to ensure your artificial light doesn’t burn your plants.

🌿  Join my "growing" community 
of 5000+ happy
cannabis farmers! πŸ‘©β€πŸŒΎ

Receive my weekly articles in marijuana growing,
from seeds to smoke! 
β€” Morgan, 420GreenThumb 🌱

Growing cannabis plants in a room

Why Are My Grow Lights Burning My Plants?

Your grow lights are burning the plants because the bulb emits excess heat. In addition, you cannot regulate the distance between the bulb and the plants effectively, resulting in too much heat on the plants.

The following are various factors that determine the effectiveness of your lights and heat on the plants.

  1. Providing excess heat.
  2. Providing insufficient light.
  3. Setting the bulb too close to plants.
  4. Using poor-quality bulbs.
  5. Using the wrong lighting.
  6. Poor lighting plan.
  7. Overwatering when switching the lights.
  8. Poor maintenance of the lights.

Providing Excess Heat

One of the common misconceptions is that LED bulbs do not produce heat. The misconception is the cause of many mistakes that gardeners make, resulting in the burning and dying of their plants.

The enclosed biodiversity of the house plants can cause LED bulbs to produce heat as high as a poor incandescent bulb, metal halide, or high-pressure sodium. The problem occurs when the heat from the diode gets absorbed by other elements in the enclosure.

The scientific process behind heat production is the diode that does not entirely get converted into light. The other reason behind heat production is the light that does not exit the diode. This light gets reabsorbed by the light-emitting diode generating more heat that burns the plants.

Blue LED lamps

Providing Insufficient Light

Insufficient light in the grow space causes the plant leaves to turn yellow and die out slowly. Your plants need enough light for photosynthesis to take place. There will be insufficient nutrients if there is poor photosynthesis, causing the plant's leaves to burn and die.

The process of photosynthesis mainly uses the blue and red light color spectrum for effective energy production. In that case, insufficient grow light will lead to a poor supply of light color spectrum, causing the plant to burn and die out.

Setting the Bulb Too Close to Plants

Setting the bulb too close to plants will emit intense light on the plants, which will, in turn, increase the heat intensity. Another critical thing to note is that the plants will require different light intensities at various stages of growth.

Once you have established the stage of the plant's growth and the proper distance, you should also ensure the wattage of the grow light source is correct. You may set the appropriate distance, but if the bulb wattage is too high, the heat will also be too high and burn the plants.

There are three critical stages of to help your plants grow that you should pay attention to when setting the grow light. These stages are seedling, vegetative and flowering. The source of grow light should be far from the seedlings at the seedling stage, while the lights should be closer to the plant during the vegetative stage. The flowering stage is the most delicate since it requires different light intensities.

Using Poor Quality Bulbs

There are different types of light LED bulbs used for plant grow lights; hence, you should choose the correct bulb for the kind of plant and stage of growth. A quality bulb should closely imitate the sun rays, which are the natural source of light that the plant needs.

The grow light bulb emits two rays: the full spectrum and red and blue lights. The full spectrum lights emit the electromagnetic spectrum, which closely imamates the sun's rays. Furthermore, the red and blue lights work in combination for good results.

There are three types of plant grow lights: incandescent lights, fluorescent lights, and LED lights bulbs.

1. Incandescent Light Bulb

The positive side of incandescent lights is their ability to emit full spectrum lights just like halogen lights. However, they are not preferable because they rerelease very high temperatures that burn plants, and they are also high-power consumers.

2. Fluorescent Light Bulb

The fluorescent light led bulb is commonly used for grow lights due to its availability and the ability to emit full-spectrum lighting. Another advantage of fluorescent light is that it doesn't release much heat that damages plants. It also consumes less energy compared to an incandescent bulb.

3. LED Light Bulb

The LED grow light bulb is the most preferred for grow lights because they emit very little heat. They are also advantageous due to their low energy consumption and durability.

In addition, the light LED bulb offers flexibility in adjusting the color wavelength. One bulb can produce a combination of red and blue wavelengths while making it the best light. That eliminates the need to have many grow light LED bulbs in the grow tent.

Using the Wrong Lighting

Various kinds of plants need different light types. In addition, the same plant may need different lighting at different stages of growth.

The following parameters help determine the proper lighting to avoid the burning of the plants.

1. Light Spectrum

A suitable grow light should constitute the full spectrum of colors that are responsible for complete photosynthesis to take place. The basic colors in the spectrum are blue light, red light, and green light.

The blue LED light facilitates the production of chlorophyll, while the red light facilitates the effective production of flowers and fruits and regulates plant growth. The green light acts as a supplement to blue light in maximizing the blue light.

Light Spectrum

2. Color Temperature

Different grow light bulbs have varying color temperatures measured in unit Kelvin (K). The color temperature refers to the appearance of the emitted light. The grow light may either be cool or warm.

3. Light Intensity

The intensity of light that the LED light LED bulb produces is responsible for the amount of temperature released by the bulb. High levels of light or temperature will burn your plants.

The following parameters help determine the correct light power for your plant:


The LED lights bulb uses Lumens to measure the intensity of light. A higher number of lumens produces a higher intensity of light, while a lower number of lumens produces a lower intensity.


The number of watts determines the level of energy that your bulb consumes when it is on. A high number of watts produces a higher intensity of light, while a low number of watts produces low intensity.

Led bulb

Photosynthetic Photon Flux Density (PPFD)

PPFD gauges the light density requirement in the grow space. The light intensity should be evenly distributed within the given area to avoid the burning of plants in some sections.


Lux is used in the LED bulb to measure the number of lumens in the grow space. Lux determines the number of lumens released within a specified square meter.

Color Rendering Index (CRI)

CRI measures the accuracy of color spectrum distribution to the plants. The CRI has a scale of 0 to 100, with a zero CRI, meaning the colors from the bulb will appear black. A CRI of one hundred means the colors will closely imitate the natural light in appearance.

Light bulbs of different colors

4. Coverage

Good quality lighting should evenly cover the plants in the grow space to ensure some plants do not burn. When determining the suitable light LED bulb to buy, you should consider its lux, foot candles, or lumens per square meter.

Poor Lighting Plan

A poor lighting plan is one of the reasons you may have a light burn on your plants. You may have all the settings right but fail to master the plant requirements at different stages of growth and time of the day.

The first step to a good lighting plan is determining the plant requirements. You should accurately determine the hours of light that the plant needs exposure in a day. In addition, you should feed the plants with enough light, the correct lighting intensity, and light spectrum.

The second step in the lighting plan is choosing the right luminaries. The plant needs different lighting at different stages of its growth cycle. That requires knowing the number of luminaries to use, the right type, and the angling.

The third step in the lighting plan is setting the lighting schedule. The right schedule will help you save power consumption, achieve lighting uniformity, and maximize light utilization.

Watering system

Overwatering When Switching the Lights

There is a direct effect of grow lights on how you water your plants. If you use HID lights, your plants will need more water than when using LED grow lights.

Your plants will need less watering if you use an LED light bulb as it generates less heat. Compared to HID lights, LED lights can save up to 50% of the water that may drain through evaporation. If you are using LED bulbs, it is recommendable to water your plants when the soil goes dry.

In addition, you should take precautions when switching the lights at different times of the day or at different stages of plant growth. Additionally, you need to take extra precautions when switching from HID lights to LED lights. Poor switching of the grow lights can burn the plants.

Poor Maintenance of the Lights

One of the most important aspects of plant maintenance is ensuring that grow lights function properly. These lights provide the plants with the energy to photosynthesize and produce food.

However, if grow lights are not properly maintained, they can burn the plants. The lightbulbs can become too hot, causing the leaves to dry out and turn brown. Additionally, if the lightbulbs are not replaced regularly, they can become dim, which can stress the plants and cause them to produce less food.

It is important to check to grow lights regularly and replace any burned-out bulbs as soon as possible to prevent the above problems. You can ensure that your plants stay healthy and happy by taking these simple steps.

How Far Should LED Grow Lights Be From Plants?

One of the most common questions growers asks about LED grow lights is how far to place them from their plants. After all, too much light can burn plants, while too little light will limit growth.

The answer to this question depends on several factors, including the type of LED grow light being used, the size of the plant, and the stage of growth. Generally speaking, it is best to start with the light a few inches from the plant and move it gradually.

You can determine how much light they need to thrive by paying close attention to your plants. With a little trial and error, you'll be able to find the perfect distance for your LED grow lights.

The Ideal Distance Between the Plants and LED Lights

You should consider all the factors, such as the type of light and type of plant, before setting an ideal distance.

The following guidelines will help you set an ideal distance between the location of the light LED  bulb and the plants.

  • If you are taking care of seedlings, you should place the LED grow lights at approximately twenty-four to thirty-six inches above the plants. Since the distance is also majorly affected by the wattage of the light LED bulb, consider locating the bulb at the highest spot at thirty-six inches.
  • You should keep monitoring the seedlings, and once the roots are established, you can place the LED light closer to the plant. That should be at approximately twenty-four inches.
  • Once the plants reach the vegetative stage, you should move the LED light closer to between twelve and twenty-four inches. It is at the vegetative stage when the plants need more light to facilitate photosynthesis, hence placing the lights closer.
  • During the flowering stage, the plants need less light; hence you should move the LED bulb further from them. The distance at this stage should be between eighteen inches to 24 inches.

    🌿  Join my "growing" community 
    of 5000+ happy
    cannabis farmers! πŸ‘©β€πŸŒΎ

    Receive my weekly articles in marijuana growing,
    from seeds to smoke! 
    β€” Morgan, 420GreenThumb 🌱

Related posts

About the author 


I discovered the benefits of Cannabis at a young age in 2002, with years of trial and error, my knowledge grew just like my plants. As my love for cannabis unfolded I began to teach and learn, trying to gain as much information and practical growing experience.

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}