How Far Should LED Grow Lights Be From Plants? Learn How high To Hang A Grow Light

Ever wondered How far away should LED lights be from plants? We show you how to evaluate proper grow light distance for yourself, for each of the growth stages for your indoor plants or type of grow light you are using.

As an indoor grower, one of the things that could be troubling is figuring out how far your grow lights should be from your plants.

The truth is, there could be multiple answers to this question, but there is a general rule you can follow, and that is called the hand test.

The hand test is when you leave your hand under your grow lights for 30 seconds and when you find the heat too much to bear, then your lights are too close to your plants.

How Far Should My Growlight Be From My Plants Led grow light distance

That’s something you don’t want as too much light, or strong intensity of lights could damage your crops, or worse, it could even kill your plants.

While the hand test could work, there are still different types of grow lights you may use when setting up an indoor garden. This determines the specific distance you should consider when it comes to your grow lights.

Here we will discuss optimal distance between your grow lights and your plants to get enough light coverage for robust photosynthesis and maximum yield in all stages of plant growth, seedling, vegetative and flowering. You can apply this information to HPS, LED T5, or CFL technology.

Importance of Grow Lights When Growing Crops Indoors

Plants require light in order to thrive and when indoors, this is one of the important factors to consider. We need to mimic how healthy plants grow outside and because of that, we need something that will substitute the sun when it comes to giving the plants what they need.

Light, whether natural or artificial, helps plants go through the process of photosynthesis. This is when plants produce glucose through the carbon dioxide, water, and light that they get. They store the glucose in their system so that they can consume it as their food and energy.

Like a lot of things, too much is just too much. Same thing with getting not enough. It just won’t work, so we have to make sure that our plants are getting just the right amount of light they need.

You need to know how long you should be exposing your plants under the light to make sure that you’re doing things correctly, but aside from that, the heat your grow lights produce also has to be considered.

There are different grow lights that you can use for indoor gardening. Some growers use fluorescent bulbs, HPS lights, and LED grow lights. What’s nice about getting LED grow lights is that these have the shades that plants need to thrive. These are the colors red and blue.


Why do Different Grow Lights Need to be Hung at Different Heights?

As you already know, there are different grow lights that you can choose from when it comes to delivering to the light needs of your plants.

However, you need to take note that not all grow lights are entirely alike. Each grow lights need to be hung differently to avoid over and underexposure of your plants to the light.

Even if all of them give the light your plants need, their intensity and spectrum are all different, and it doesn’t mean that you can have them placed above your crops in the same manner.

Here we will tell you what those are and how far you should be placing them from your crops.

HID Light Spacing: How close is too close?

HID or High-Intensity Discharge grow lights can produce a strong amount of heat while it’s turned on. With that said, if you’ll be using these as your light source, this should not be placed too close to your plants as it will quickly dry them up.

HID Grow Light distance from plants

Here’s a suggested guide on how far you should be placing the HID grow lights away from your plants based on the wattage:

Wattage

Suggested Distance

400W – 600W

12 to 19 inches away from your plants

600W – 1000W

14 to 26 inches away from your plants

More than 1000W

16 to 31 inches away from your plants

Now, even if HID grow lights produce can produce intense heat, it doesn’t mean that it should be placed way too far from your plants.

Underexposure to lights will also cause you a problem. You should really take note of the maximum distance for each wattage to be sure all your plants will get enough light.

fluorescent grow light distance

There are different types of fluorescent grow lights like T5s, CFLs, and T12 so there will be differences when it comes on distancing them from your plants.

T5s and T12s do not really produce enough light to cause light stress or burn on plants but do take note that T5s has higher light output. That said, T5 is still more intense than T12s.

CFLs, on the other hand, can produce heat that can build up, especially if you’ll get the compact ones. However, this is generally not too intense that it produces heat that could kill your crops.

The general rule you can follow when it comes to using fluorescent T5 grow lights is to keep them at least 12 inches away from your plants. When your plant grows, that’s when you can just readjust the distance.

Metal Halides and HPS Grow Lights

These two usually both comes together in kits as they both help in giving the right spectrum to your plants. Metal Halides provide the cool spectrum which is good for the vegetative stages, while the HPS (High-Pressure Sodium) lights are ideal for the flowering stage.

We’ve come up with a guide you may use when it comes to distancing them to your plants based on their wattages.

Wattage

Suggested Distance

150 W

8 to 12 inches

250 W

10 to 14 inches

400 W

12 to 19 inches

600 W

14 to 25 inches

1000 W

16 to 31 inches

Remember to keep an eye on your plant’s growth as you need to adjust the distance of your grow lights once the plants grow taller. If you don’t do this, it will hurt the tip of your plants.

How Far Should Led Grow Lights Be From Plants

With right distance, you’ll be able to grow strong and healthier plants or crops as this won’t burn them out. Keep in mind that grow lights as LEDs can easily burn your plant out if it’s placed way too close to your crops.

When plants are overexposed and are grown too close to their light source, you’ll see that they’ll acquire bleaching and have yellow spots all over their leaves.

This could also cause them to have nutrient deficiencies that we’d really need to avoid.

The distance really varies and so there’s nothing specific when it comes to the distance of your LED grow lights form your plants.

When we say it varies, what we consider is the shape, size, and wattage of the LED grow lights that you have.

How Far Should LED Grow Lights Be from Plants

You need to check the specifications of the LED grow lights you purchased. If it doesn’t have any recommendations when it comes to how you should be placing it in your grow room, tent, or space, it’s always best to contact the manufacturer.

This is why it’s advisable to get an LED grow light from trusted manufacturers or brands.

Unlike other types of grow lights, it could be a bit complicated to know how exactly far your LED grow lights should be from your plants.

Led Grow Light Distance Chart 

There’s no exact computation to help you determine how far your grow lights should be from your plants, but here is a guide that we can share with you:

LED grow lights Wattage

Distance from Plants

1 watt

16 inches or 30 cm from your plan

3-5watts

20 inches or 30 cm from your plants

6-10watts

21 inches or 53 cm away from your plants

200 watts

12 to 20 inches away from your plants

250- 400watts

16 to 30 inches away from your plants

450- 550 watts

20 to 30 inches away from your plants

600- 800 watts

28 to 42 inches away from your plants

900- 100 watts

36 to 46 inches away from your plants

MEASURE HOW MUCH LIGHT YOUR PLANTS ARE GETTING

Keep in mind that LED grow lights can wilt and burn your plants even if they don’t really produce much heat.

If you want to be sure you’re not going to overexpose your plants, you can always have it placed as far as you prefer. What’s important is that all your crops are lighted evenly.

This could be a trial and error process when it comes to perfecting the distance of your LED grow lights from your plants, so be patient and alert to see how your plants are doing with the distance you’ve set.

Generally, it’s safe to say that you should keep the grow lights at least inches away from your plants.

There are flowering plants, like orchids and citrus that require a high light intensity to flower and produce fruit.

This means that the grow lights should be placed closer to these plants. ZZ and Snake plants only need low light intensity, and so your grow lights should be placed farther.

Lux Meter to measure light levels in your grow room

A lux meter is used to measure brightness levels. This could help you have a better grasp of the distance that you should be giving between your plants and grow lights.

Remember that this doesn’t measure the heat the light emits, but it only measures the brightness. To be more specific lux meter can only measure the brightness based on what humans can see.

Even if it doesn’t measure the heat, this can still be an accurate reference for you to know what would work best with your plants. Here is a guide chart you can check:

Stage

Lux Measure

Vegetative

15,000 Lux to 70,000 Lux

Flowering

35,000 Lux to 35,000 Lux

Clones and seedlings

5,000–7,000 Lux

Conclusion

As of today, LED grow lights are widely used for indoor gardening mainly because of is spectrum capability. It is less expensive and runs longer than other types of grow lights.

While you can already have this during seeding or germinating, the best time for you to really reap the effects of LED grow lights is during the flowering and vegetative stage.

Remember that this shouldn’t be something to miss when growing plants indoors!

I hope that you find this very useful when it comes to keeping your plants and crops string and healthy. Have fun growing plants indoors!

Ever wondered what the optimal distance is between your grow light and your plant

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  • Are lux level recommendations for normal sun or color-controlled grow light sources?
    Do you know if photographic lux meters are affected by color of the emitting source?
    Do lux level recommendations vary for different plant species?

    • The following intensity values in footcandle are given for some light conditions (Janick 1972): starlight- 0.0001, moonlight- 0.02, indoors near window- 100, overcast weather- 1000, direct sunlight- 10,000.

      High light intensity means it is brighter compared to low light intensity. Some terms that are used with reference to light intensity are open or full sun, partial sun or partial shade, and closed or dense shade. Based on adaptation, crops can be classified as sun plants and shade plants with various intergrades in between.

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