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How Far Should LED Grow Lights Be From Plants?

Table of Contents

Understanding LED Lights

Determining the Best LED Grow Light Placement

  • Setting Up Reflective Walls + Pros & Cons
  • Using Overlapping Lights + Pros & Cons
  • The Plant's Growth Stage Determines the Distance

  • Seedling Stage
  • Vegetative Stage
  • Flowering Stage
  • Monitoring the Health of Your Plants

    Final Thoughts





    Today, many growers are switching to LED lighting and evolving from the traditional HID and fluorescent lighting systems. Not only are LED lights more cost-efficient, but they also emit less heat. Across many sectors, LED lights are becoming preferred over other types of lights.

    One popular question growers ask themselves is "how far should LED grow lights be from plants?" Knowing the right way to use your LED lights will save you the struggle of ending up with an unhealthy crop. You'll save yourself a lot of time if you know about how to use LED lights to your advantage. There is a science behind properly growing plants with LED lights that will give you the full benefits of your efforts.

    This article will discuss how to set the optimal distance of your LED grow lights so that your plants can thrive at every stage of their development. We'll help you understand the particular factors involved with LED lighting systems and how the distance in which you place your grow lights impacts the plants at their various growth phases.

    No need to guess or wing it, it is best to know what your plants need and how to use your equipment properly, so you can reap the full benefits of your crop.

    Understanding LED Lights

    First, we want to point out the difference between LED lights and traditional growing lights. LED systems emit low heat compared to HID and fluorescent sources. This means that the placement distance will be different.

    LED lighting systems for growing plants have revolutionized the horticulture industry. They are allowing growers to produce their best indoor crops ever seen. LED lights have variable spectrum control and high-intensity, which perfectly mimics natural sunlight.

    Some major advantages of LED lights are that they have minimal energy consumption and emit very low heat. However, it is still essential to know how to use these innovative lights to their fullest potential. If used incorrectly, they can harm to your plants, as with any type of lighting system.

    Since LED lights vary according to the manufacturer and there are no set industry standards for usage, it is important to fully research the product you're using. Manufacturers usually provide an LED grow light distance chart for guidance. You may also find online resources that have particular information about the system you're using. There are many forums that provide user reports from real people that have experience using your type of LED lights.

    Determining the Best LED Grow Light Placement

    Artificial lights that replicate sunlight are referred to as a point source. A mathematical concept called the Inverse Square Law describes the relationship between the light intensity (output) from the point source and the distance from the plant.

    When shopping around for different LED grow lights, it is important to note the wattage. How far should led grow lights be from plants depends on wattage. The higher the wattage, the more distance you'll have to allow to avoid damage to the plants.

    Let's review other terms you'll need to be familiar with to purchase and use LED lights effectively:

    Knowing the light intensity an LED system offers and the PAR required for your specific crop is the basis of choosing the best light source and implementing the appropriate placement.

    There are methods such as using reflecting walls and overlapping lights to achieve better results.

    Setting Up Reflective Walls

    The Inverse Square Law, meaning the relationship between the intensity of the light and the distance from the plant changes significantly when reflective walls are used. Reflective walls are like a mirror that bounces the light on the plants as the distance increases.

    No matter where you need to place the lights, whether higher or lower, reflective walls will ensure that the plants are penetrated with light from various angles leading to thorough penetration and an even yield.


    • Helps to keep buildings cool, especially in warm climates
    • Are very durable, are resistant to moisture, and don't degrade as time passes
    • Easy to use, lightweight, and comfortably fit to most spaces
    • Waterproof material makes them great for acting as a vapor barrier
    • Made from safe materials compared to other insulation products that contain toxic and carcinogenic substances


    • Metal-based material may be expensive for some people
    • Requires additional insulation in cold climates to prevent the loss of heat
    • Metal material can pose as a fire hazard if electrical wires are faulty
    • Must be regularly maintained to ensure dust or debris doesn't build up and interfere with its proper function

    Using Overlapping Lights

    Another way to ensure your plants receive enough light from different angles is by overlapping multiple lights in the same room while using reflective walls. This method is more appropriate in larger grows that require more lights and are situated in a more spacious room.

    An effective method for using multiple light sources is to put the fixtures at a higher level to create an overlap of beams that evenly and intensely penetrate the plants. This is not only more healthy for the plants, but it will also provide a better yield because of the abundant light they consistently receive.


    • It turns out to be more cost efficient in the long-run
    • The plants receive consistent uniformity of light levels
    • You may combine different light spectrums to provide plants maximum support
    • Various angles provide exceptional crop penetration


    • May not be practical for every space, it requires a large room
    • Must be calibrated and done carefully because too much light can harm the plants
    • It is only practical for large grows, it doesn't make sense for small projects

    The Plant's Growth Stage Determines the Distance

    There are no set universal rules when it comes to growing plants. Various factors have to be taken into account and considered on a case-by-case basis. With time, you'll know how to exactly fine-tune the formula for each scenario.

    One of the factors you must consider is that LED lights are designed in different ways depending on the manufacturer. Remember to find a LED grow light distance chart to help you determine the right strategy.

    Another factor to consider is the stage of growth your plant is experiencing and the intensity of light it requires at that stage. Some lights have a great design that allows you to dim them. However, if you don't have a dimmer on your lights, the other option to decrease its intensity is to change the height of placement over your plants.

    Consulting your light's manufacturer is the best way to know what to do at each growth stage.

    1. Seedling Stage

    After germination from a seed, the plant enters into the seedling stage and develops characteristic leaves. Its roots are small requiring very little water. They do need plenty of light, but at a low intensity. This means they require the most distance from the light source while still receiving even distribution.

    Some might think plants at the seedling stage need high-intensity light to trigger lots of growth, but in fact, plants at this stage do better with a much gentler approach. They are young and vulnerable and must be carefully handled.

    There are two priorities when providing light for your seedlings: The amount of light and the amount of coverage.

    Typically, if you're using a Phillips LED bar, the distance will be 24-36 inches away from seedlings. Using multiple LED bars will ensure proper coverage.

    Depending on the plant, the seedling stage lasts anywhere from two to three weeks and requires light for approximately 16 hours per day.

    2. Vegetative Stage

    At the vegetative stage, the plant quickly starts to grow and needs to be transferred to a bigger pot to let its roots expand. The foliage develops at a very fast pace and stalks start to thicken. Along with plenty of water, plants at the vegetative stage need an abundant amount of nutrients.

    The vegetative stage can last from three weeks to four months. They are at the peak of their photosynthesis process gathering lots of light and turning it into foliage, getting ready for flowering and reproduction.

    Depending on the plant, during the vegetative stage, it is typical to provide 18 hours of light per day along with six hours of complete darkness. At this stage, LED lights can be placed 12-24 inches away from the plants.

    3. Flowering Stage

    Finally, the plant reaches the flowering stage where it starts to develop buds that will become flowers. You can start to see this happen after eight to nine weeks depending on the plant species.

    At this point, the plants continue to require plenty of nutrients, but in order for them to start flowering, they require 12 hours of continuous darkness.

    If too much light is received, they may stay at the vegetative stage. Therefore, LED lights must be set at the proper schedule and should be placed approximately 16 to 36 inches away.

    This stage lasts for about eight to eleven weeks.

    Monitoring the Health of Your Plants

    A major advantage of using LED lights is that they don't give off much heat, thus it minimizes the chances of your plants being damaged. Light burns are often mistaken by a nitrogen deficiency, which causes growers to provide a faulty solution.

    A correct assessment of your plants is necessary to fix any problems that may arise. Watch out for the following symptoms that may indicate light burns:

    • Leaves start to point upwards
    • White or yellow discoloration on the leaves closer to the light
    • Leaves turn yellow while veins remain green

    Since the appearance of light bleaching or burns and nitrogen deficiency are so similar, it is important to note the symptoms of nitrogen deficiency:

    • Yellow patches develop on the leaves from the bottom towards the top
    • Leaves start to wilt
    • Leaves fall out on their own

    If you suspect that your leaves have light burns or bleaching, you'll want to consider adjusting the height of the light.

    Final Thoughts

    As you can see, your horticulture success depends on many variables. Fortunately, most of them are under your control. Even if you're an experienced grower, you'll learn something new each time you grow a crop.

    The main components of success include becoming familiar with the species of plants and their needs. You also have to know your equipment, its capabilities, plus the recommendations provided by the manufacturer. Knowing the growth stages of the particular plant you're growing will determine how far your LED lights should be placed.

    Finally, learning how to make the proper adjustments and spot damage on your plants will allow you to tweak your strategy until you reach a healthy balance. As you practice, you'll know exactly how far LED grow lights should be from plants for them to thrive and provide the best yield.

    Choose a manufacturer that provides user reports with expert advice. You should also stay connected to various online forums that have lots of anecdotal reports to help you at each step of the process. The growing community is stronger than ever before and we now have many resources at our fingertips. That's all you need to know about, "how far should led grow lights be from plants


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