LED Grow Lights Distance for Cannabis & Other Plants - BIOS Lighting (2022)

LED Grow Lights Distance for Cannabis & Other Plants - BIOS Lighting (1)

Today, more growers are moving away from traditional HID and fluorescent T5 grow lights and are installing LED lighting. LEDs emit less heat than HID sources which means that the proximity of LED grow lights to the canopy varies from that of traditional grow lights. It is important to also understand how optimal grow light distance impacts the different phases of plant growth.

See all available Cannabis Grow Lights by BIOS

This article outlines the different lighting needs for a variety of plants, (including cannabis) according to their growth stage. It also addresses how to determine the proper distance of LED lighting from the plant canopy to nourish plant growth, as well as the importance of PPFD (PAR), and other popular grow light terminology.

How To Measure Light for Plants

Let’s quickly define PAR and PPFD. PAR (Photosynthetically Active Radiation) describes the portion of the visible spectrum that plants “see” and use for photosynthesis (400nm-700nm). PPFD (Photosynthetic Photon Flux Density) measures the amount of light (PAR) a plant receives over time. PPFD represents the light density a plant receives over time and is measured in micromoles [of photons] per square meter per second (1).

A way to visualize PPFD is to imagine the sun is “pouring” light onto the plant leaves. As the sun pours light onto the plants, their leaves are collecting the energy. PPFD is the measurement of the amount of light (photons) the sun “pours” onto the plants over time. PPFD is an important metric because it helps growers accurately measure the light intensity for photosynthesis at the canopy level. It is also important because lights placed too close to the canopy can cause burning, bleaching, stunted growth, or discoloration.

LED Grow Light Distance Chart

LED Grow Lights Distance for Cannabis & Other Plants - BIOS Lighting (2)

(Video) How Far Should LED Grow Lights Be From Plants? - FAQ

Distance from

Plant Canopy

(meters / inches)

Intensity

(Lux)

PPFD / PAR

(μmol/m-2/s-1)

Coverage or “Light Footprint”

(m² / ft2)*

2m / 79 inches955lx6707.6m2 / 81.8ft2
1.5m / 59 inches1692lx11705.0 m2 / 53.8ft2
1m / 39 inches3663lx16703.0 m2 / 32.3ft2
0.5m / 20 inches12,500lx21701.5 m2 / 16.1ft2
0.2m / 8 inches50,300lx26700.5 m2 / 5.4ft2

* Coverage will vary based on the grow light being used. LED source shown here does not use a reflector to direct the light

Table 1: Distance of LED Lighting from Plant Canopy (600W LED Grow Light)

Table 1 shows how a 600W LED grow light performs at varying distances from the plant canopy. It outlines light intensity (lux), delivers PPFD (μmol/m-2/s-1 or micromoles per square meter per second), and also shows the “light footprint” or canopy coverage. Intensity, PPFD/ PAR, and “light footprint” all change as the distance of the light from the plant canopy increases or decreases.

Table 1 also highlights how changing the distance of the same 600 watt LED light changes the light intensity and “light footprint” or canopy coverage a plant receives. As the light source is located closer to the canopy, the light intensity increases. In general, grow lights should be mounted closer to the plant canopy for vegetative stages of growth and higher up (further away from) the plant canopy during the flowering stages of growth.

Where Should Grow Lights Be Located?

For seedlings, LED grow lights should generally be mounted between 24-36 inches above the plant canopy – however, this depends on the power (wattage) of the light source. Locate your LED grow lights at the furthest distance from the seedlings (~36”) – this keeps heat and light intensity levels lower and helps prevent seedlings from drying out. Once roots have been established and sprouting has started, the lights can be moved closer (usually within the first 2-3 weeks).

(Video) How Far Should Grow Lights Be From Plants? Learn How high To Hang A Grow Light

In the vegetative stage, LED grow lights should be between 12-24 inches away from the top of the canopy. During this stage, more light is needed for photosynthesis, so the light source should be located closer to the plants.

As the plants progress through the flowering stage, their demand for intense light decreases. The top leaves of the canopy should be between 18-24 inches from the light source to produce flowers. It is at this stage that the plants increase in height and grow fruit. Depending on lights and how you want your crop to grow, it is not necessary to change the height of the lights during flowering, especially if you do not want taller plants.

How Far Should LED Grow Lights be from Seedlings?

At the very early stages of growth, seedlings are delicate and require less light intensity. This means you do not want to turn up the intensity too early as the seedlings will thrive with a far gentler approach. Depending on the size of the light, it is safe to keep grow lights located somewhere between 24-36 inches from the top of the soil.

How Far LED Grow Lights Should be From Clones

Cannabis cloning is a process where clippings or cuttings from a mature plant are used to grow another plant of the same kind. The LED grow light distance above the clones differs from the height required for seedlings. With clones, they will need intense light to begin. Depending on the power of the light and maturity of the plants, this could vary quite a bit between 14-36 inches from the top of the plant canopy.

How Far Should LED Grow Lights be for Flowering Plants

As plants grow, their needs change. Once the vegetative stage is complete, plants enter the bloom or “flowering” stage. For established plants, they are already where they need to be in order to thrive. During the flowering stage LED Grow lights should be located between 16-36 inches from the plant canopy. Moving the grow light closer will increase the light intensity which can maximize photosynthesis. However, if the grow lights are too close above plants, they can cause wider, more sprawling growth or can even damage the plant.
What about Other Stages of Growth? (H2)

Plants require different levels of light depending on each stage of growth. To understand exactly how far grow lights should be from plants, it is important to factor in the different stages of growth (2). It is also important to consider the power output of the grow light — this usually is related to the wattage of the light source, which is a primary factor in determining the optimal distance for LEDs when starting the growing process.

Plant growth can roughly be divided into three different stages – Seedling, Vegetative, and Flowering stages.

This means once healthy roots are firmly established, it’s time to increase the intensity and lower the lights.

Seedling Stage

During the initial stage as seedlings, LED grow lights should be placed higher up from the plants to avoid drying out the soil.

Some growers may be tempted to blast seedlings with a high-intensity light to promote faster growth, however, this will not help until the plants become established. Seedlings are too vulnerable in this early stage and require a gentler approach. Once plants mature, then higher light intensity is required to promote photosynthesis.

(Video) INCREDIBLE CLOSET GROW USING LED GROW LIGHTS

Vegetative Stage

During the vegetative stages, plants respond well to intense light – it is during this period that they are maturing and using photosynthesis to grow quickly. To increase the light intensity, LED grow lights should be located closer to the plant canopy. Strong, healthy stems and roots are key for a successful and repeatable yield.

While increasing light intensity promotes growth in the vegetative stage, it is important to closely monitor your plants, making sure to look out for adverse symptoms caused by too much light or not enough.

Flowering Stage

Flowering is the final stage of a plant’s growth cycle — during this time fruit production and stem growth accelerate. As plant growth transitions from the vegetative to the flowering or bloom stage, it is good practice to “phase” this transition process. To do this, gradually raise the height of the LED grow lights away from the plant canopy (using the height recommendations outlined earlier). Monitor the distance closely, keeping in mind the desired crop height and flowering needs for the specific plant/crop.

Adverse Effects of Too Much Light

When a plant like cannabis receives too much light at any stage, they often show symptoms of distress. Since LEDs do not give off much heat, the main issue that needs to be closely monitored is any indication of “light burn”. Other side-effects related to grow lights that have been placed too closely to the plant canopy could be discoloration or stunted/irregular growth. Both of which must be identified quickly and the grow light height adjusted accordingly.

Signs of light burn in cannabis plants include upward-pointing leaves and what is known as “bleaching”. Bleaching is the white or yellow discoloration on the leaves closest to the light. Light burn can also be identified when the plant veins stain green as the rest of the leaves turn yellow.

Grow Light Distance – Cannabis vs. Other Plants

Using LED grow lights for cannabis production has become more popular as growers have moved crop production indoors. LED has also provided a benefit to growers because they can utilize specific light spectra to provide more targeted lighting conditions for different crops. Additional benefits when considering LED grow lights include lower power consumption, reduced forward heat, and increased yield over a shorter period of time as compared to traditional sources.

Grow light distance should reflect growers’ desired height and uniformity of their plants, with a nice spread of leaves and healthy flowers. If we look at the crop needs for salad greens or lettuce compared to cannabis, we see that salad greens and lettuce are suited to short, wider growth, whereas cannabis is more suited to taller, narrower growth.

Regardless of your crop type, farmers and cannabis growers alike want maximum-quality yields over a shorter growth cycle.

Lighting Distance for Traditional Grow Lights

Before LEDs became popular for indoor growing applications, traditional High Intensity Discharge lamps (HID) like High Pressure Sodium (HPS) and metal halide, as well as fluorescent lamps, were widely used. These lamps historically have had a much lower first-cost than LED grow lights, making them more affordable to purchase and therefore accessible for large-scale indoor growers.

The distance that HID or fluorescent grow lights should be from the plant canopy is greater than from LED. This is partially because they give off more forward heat than LEDs, but they also are only available in a few different wattages/light outputs. The distance that grow lights should be mounted varies for each stage of growth and depends on the wattage of grow lights used.

(Video) ✅ 10 Best Grow Light New Model 2022

While traditional grow lights have a lower first cost (they are less expensive to buy) they require more maintenance over time – the bulbs need replacing and/or cleaning more frequently – and they have significant limitations related to lighting controls – many do not dim and can take a long time to turn on to full light output.

Fluorescent Grow Lights

There are three (3) basic types of fluorescent grow lights – T5, T12, and Compact Fluorescent Lamps. To achieve different light intensity, growers must adjust the height of the lamps from the plant canopy accordingly. One benefit to fluorescent is that it is very difficult to cause light burn because they don’t emit enough heat. Regardless, light intensity and heat should always be closely monitored.

For young crops, approximately 6-12 inches is a sensible height to begin since they need a higher intensity of light. As they mature from vegetative through flowering, it’s wise to double this distance to around 12-16 inches. As a general rule, when T5’s are used it’s wise to keep them as close as possible but to monitor overheating or drying out.

HID Grow Lights (Metal Halide and High Pressure Sodium – HPS)

Metal Halide (MH) lamps provide a large amount of blue light – the spectrum considered best for the vegetative stages of growth (3). High Pressure Sodium (HPS) lamps are ideal for both vegetative and flowering. Both of these produce significantly more heat than LEDs but are relatively inexpensive to buy.

One way you can test the heat of HIDs is with the back of your hand. This can help you gauge the right grow light distance. Simply place your hand just over the top of the canopy and hold it there for 30 seconds. Your hand should become hot, but not unbearable. If this happens, increase the grow light distance above the plants.

Many commercial growers use 1000W HID lighting, which normally would see a height of 19-26 inches used to begin. From here, they can gradually be moved closer.

However, since HIDs produce a large amount of heat it’s critical to avoid heat burn since this will damage any plant. Plus, indoor ventilation is very important with HID lamps due to the higher heat they give out.

With 50 years of collective experience and expertise, BIOS Plant is a leader in LED grow lighting solutions and continues to innovate and push the industry forward. BIOS biology-first and research-based approach to LED grow lights are led by nature as we build brilliant full spectrum LEDs so plants grow stronger and yield more – from seedlings to maturity.

With a 50% reduction in electricity consumption and up to 50% less heat produced compared with HPS, our SSL grow lights provide your plants with natural light for up to ten years. The BIOS Icarus® line of LEDs provide optimized light spectrums for superior results which also use plug and play configuration. Our grow lights are easy to set up with effortless maintenance, backed by our ongoing commitment to support our partners’ LED integration.

See all available Cannabis Grow Lights by BIOS

(Video) The Future of Vertical Farming: Growing Smarter with LEDs

  1. Park, Y., & Runkle, E. S. (2018). Spectral effects of light-emitting diodes on plant growth, visual color quality, and photosynthetic photon efficacy: White versus blue plus red radiation. PloS one, 13(8), e0202386. <https://doi.org/10.1371/journal.pone.0202386>
  2. Niinemets, U., & Keenan, T. F. (2012). Measures of light in studies on light-driven plant plasticity in artificial environments. Frontiers in plant science, 3, 156. <https://doi.org/10.3389/fpls.2012.00156>
  3. Pennisi, G., Orsini, F., Blasioli, S., Cellini, A., Crepaldi, A., Braschi, I., Spinelli, F., Nicola, S., Fernandez, J. A., Stanghellini, C., Gianquinto, G., & Marcelis, L. (2019). Resource use efficiency of indoor lettuce (Lactuca sativa L.) cultivation as affected by red:blue ratio provided by LED lighting. Scientific reports, 9(1), 14127. <https://doi.org/10.1038/s41598-019-50783-z>

FAQs

How far should my cannabis light be? ›

Once roots have been established and sprouting has started, the lights can be moved closer (usually within the first 2-3 weeks). In the vegetative stage, LED grow lights should be between 12-24 inches away from the top of the canopy.

How far should a 1000 watt LED light be from plants? ›

Lower wattage LEDs of around 200 watts should sit between 12-20 inches from the top of the plant. Higher wattage LEDs of 1000 watts and above should sit between 36-46 inches from the top of the plant.

How high should my LED light be above my plants? ›

So the ideal way to use an LED light is to place it as close as possible to the canopy without burning the plants. In well-ventilated areas, we have found the mounting height to be as close as 6 inches.

How far should a 600 watt LED light be from plants? ›

LED distance from plants and LED wattage
WattageDistance from top of plant (inches)
200-39912-20″
400-59920-27″
600-79930-38″
800-99932-42″
1 more row

How far should lights be from plants? ›

In general, you'll want to hang your light no more than 12" away from your plants. - Remember: after 12" fluorescent lighting loses its power, so make sure you don't raise it any more than 12" above your canopy otherwise your plants aren't getting light energy.

How many LED grow lights do I need? ›

How many plants per LED grow light?
Grow Room SizeSquare FeetRecommended # of Plants in Veg
1' x 1'1Up to 2
2' x 2'4Up to 4
3' x 3'9Up to 9
2' x 4'8Up to 8
6 more rows
5 Mar 2021

How many plants can a 1000W LED light grow? ›

Yield Lab 1000W HPS+MH Cool Hood Reflector Grow Light Kit (Price: $239.95) — With a 1000w grow light, you'll get 130,000 lumens from an HPS bulb and 110,000 lumens from an MH bulb. That's sufficient to provide coverage for up to 6 plants.

How many plants can I grow with a 600w LED light? ›

2 month plants should give about 40g per plant, so with about 9 you'll be able to easily fill a square meter and get up to 400g per 600w light. 3 month autoflowering plants grow much bigger, however, so you should only plant 4 per 600w light.

How do you know if your plant is getting too much light? ›

Telltale Signs of Too Much Light

The most apparent sign is leaf burning. This typically causes the yellowing of leaves at the top of the plant but the veins stay green, and the leaves take on a yellow or brown, burnt look.

Where should grow lights be placed? ›

Ideally, a grow light or bulb should be placed within a couple of feet of a plant to ensure it receives enough light. It is usually also best to place the light directly above a plant, rather than off to the side as this could cause the plant to grow sideways and “reach” towards the light.

Should I leave a grow light on 24 hours? ›

A: In general, you should not leave grow lights on 24/7. Plants need a light-dark cycle to develop properly. It's believed that they truly do “rest” during periods of darkness, and probably use this time to move nutrients into their extremities while taking a break from growing.

How much area does a 600 watt grow light cover? ›

A 600 watt will cover 6x6 feet, a 400 will cover 4x4 feet, a 250 will cover 3x3 feet and a 150 will cover 2x2 feet. Higher wattage lights will cost more to operate, you can estimate operating cost with our cost calculator.

How far should T5 grow lights be from plants? ›

When it comes to hanging your T5 grow lights, you'll want to hang them around 12 to 18 inches above your plants. Unlike HIDs that you'd need to hang 18 to 20 inches above plants, and LEDs that need 20 to 24 inches of space above plants, T5s don't have the same intensity as other lights.

Do grow lights have to be above plants? ›

Types of Grow Lights

LED grow lights should be suspended higher above the plant canopy than HPS lights because they produce higher light spectrum output (known as PPFD). Hung too close to plants, they can cause bleaching and reduced productivity.

Can you have too many grow lights? ›

Is there a downside to having too many grow lights in our grow rooms? The answer is yes, and there is economic and scientific evidence to back it up. First, we need to consider what is cost-effective and ecological. Many grow rooms are set up with a lot of grow lights and ballasts that need to be purchased up-front.

Can LED grow lights burn plants? ›

While LED lights do produce some heat, they deal with that heat more effectively than other light types. Plants can grow much closer to LEDs than other lighting types because of this. Usually crops can grow right up to the light without burning.

How far should LEDs be from seedlings? ›

Different plants have different light intensity needs, but most seedlings grown for the garden will need higher intensity light to flourish. In general, the leaves should be about 2 - 4 inches away from the light source (assuming use of a fluorescent bulb – see below).

How far should my light be from my seedlings? ›

Different plants have different light intensity needs, but most seedlings grown for the garden will need higher intensity light to flourish. In general, the leaves should be about 2 - 4 inches away from the light source (assuming use of a fluorescent bulb – see below).

How do you know if your plant is getting too much light? ›

Telltale Signs of Too Much Light

The most apparent sign is leaf burning. This typically causes the yellowing of leaves at the top of the plant but the veins stay green, and the leaves take on a yellow or brown, burnt look.

How do you know if your plant is not getting enough light? ›

So, how do you know if your plant is not getting enough sun? Common signs include stretched or leggy growth, abnormally small leaves, pale green or yellow leaves, and slowed or stopped growth. Flowering plants may flower only sparsely or not at all, and plants with variegated leaves may turn completely green in color.

How far should light be from Autoflower? ›

Most lights are placed at a distance of at least 18-22 in (46-56cm) away from seedlings, and you can do that too. Once you observe how the plants react, you'll be able to judge the distance yourself. Autoflower seedlings need to be observed much more because the plants can get stunted if the tender leaves get burnt.

Videos

1. What it Means to Build High-Performance LEDs with the Grower in Mind
(BIOS Lighting)
2. Do Amazon LED Grow Lights Work For SEEDLINGS and VEGGIES? The Simple Truth
(Expedition Homestead)
3. Full spectrum grow light comparison test - COB vs Red Blue LED vs CFL
(MIGRO)
4. DIY LED basics: getting started building your own grow lights: (pt 1/6)
(growmau5)
5. The Best Light Setup for Growing Cannabis: Beginners guide!
(The Cannabis Experts)
6. Bios Icarus 4x4 week 5.5
(The Cannabis Specialists)

Top Articles

You might also like

Latest Posts

Article information

Author: Tyson Zemlak

Last Updated: 11/05/2022

Views: 5394

Rating: 4.2 / 5 (43 voted)

Reviews: 90% of readers found this page helpful

Author information

Name: Tyson Zemlak

Birthday: 1992-03-17

Address: Apt. 662 96191 Quigley Dam, Kubview, MA 42013

Phone: +441678032891

Job: Community-Services Orchestrator

Hobby: Coffee roasting, Calligraphy, Metalworking, Fashion, Vehicle restoration, Shopping, Photography

Introduction: My name is Tyson Zemlak, I am a excited, light, sparkling, super, open, fair, magnificent person who loves writing and wants to share my knowledge and understanding with you.