How high should I hang my 480W LED grow light?

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.

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 high 480W LED grow light place?

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.

Use The Inverse Square Law To Determine Grow Light Hang Distance Above Your Plants:

The inverse square law is a physics law that can help you to determine how intense your grow light is at a specified distance from your plants, which will help you determine whether you need to hang the grow light closer or further away from your plants.

The inverse square law of light applies to grow lights in that when a plant’s distance from a grow light doubles, the area covered in light increases, but the intensity of the light decreases to 25% intensity of the original distance.

Notice the intensity at 2 meters in the image above is 25% of the intensity at 1 meter. The intensity at 4 meters is 25% of the intensity at 2 meters. This will hold true for your grow light intensity at a distance from 6 to 12 inches, 12 to 24 inches, 24 to 48 inches, etc.

Even though the distances in the image above are meters, the law holds true for any distance. If your starting distance is 1 foot, the intensity will be 25% at 2 feet, and 11% at 3 feet. The intensity will be 25% of the 2 foot reading at 4 feet, and 25% of the 3 foot reading at 6 feet.

ECO Farm ECOT 480W Dimmable Samsung LM301H Quantum board LED Grow Light with UV&IR

Pros

Saves energy costs

Enables year round production

Has an advanced cooling system

Cons

Light frequency is a bit lacking

Lamp quality needs to improve

HYPHOTONFLUX HPF4000 Full Spectrum Led Grow Lights For 5x5ft Coverage

Pros

Multiple heat sinks

Upgraded aluminum radiators

Two multiple high-speed mute fans

Cons

Not waterproof

For indoor use only

The Different Types of LED Grow Lights

Growing the hemp or cannabis anywhere using LED grow lights can be an interesting activity. Very few people actually know that these grow lights are available in a number of different types. However, a few of these varieties are very frequently used for growing these plants. Knowing these LED varieties is important and can help you make a better decision while investing in any set of grow lights.

Here are some of the most common types of best LED grow lights. We are not in the position to rank any of these varieties as the best or the worst type. The extent to which they can suit you is a relative idea and can be decided by what you expect your grow lights to do and how you use them.

So, let us jump right into the types of these LED Grow lights:

COB LED Style

COB stands for Chip on Board. Actually, these COB lights are like very big LED lamps with a lot of small bulbs inside each lamp. These smaller bulbs are further made up of many small LED chips. There is a small board inside the bulbs where all the chips are attached together. The intensity of numerous chips in such a limited space creates a very bright and intense lighting effect.

This high intensity of light in these COBs helps them throw more light on the under-growths. However, because they are intense, these lights need a lot of electrical energy and may increase the cost a lot.

Auto-COB LED Style

As their name suggests, these LEDs are also like the COB ones and have similar functionality. However, unlike the COB lights in which there are multiple bulbs per lamp, these lights have a single Bulb in each lamp. These LED grow lights are usually used where one needs to shed the similar level of light throughout the planted area.

However, you can also use these lights in different blub forms to make a customized spectrum of lights. This differing spectrum can help you focus different light intensity on different plants. This can turn their uneven growth to even in a manner that, after some time has passed, all the growths will have achieved similar length.

Spread Style LED Lights

These LED grow lights are unitary systems that spread out light on a large area using small LED bulbs. These spread lights are either available in the form of spider style LEDs or are like a single quantum board. These lights have low watt diodes that spread out light on a large area.

Why are LEDs a good choice to grow Marijuana and Cannabis?

Getting a plant to grow indoors is a full-time task. You are supposed to provide the best possible form of light with the highest possible intensity. LEDs, if compared to any other artificial light source, are the only form of light that one can rely on in terms of intensity.

Including all other benefits of LEDs, there are a variety of features these lights have that can make them the best choice for plant’s growth. No matter how much of these you use, the energy consumption of these lights will be far lower than any other source of light you will use to grow the plants. The plus point here is the average billing that comes without having you to compromise on the intensity of light at all.

LED lights usually last longer than any other light source and are usually priced reasonably. All of this combined with the fact that these LEDs can provide instant bright light to your plants makes them an event better plant growing source. Other features including the idea of these lights being environment friendly, incapable of producing harmful UVs, and their strong build are enough to regard these lights as the best choice to help your plants grow.

LED Grow Light Placement

If you do not have reflective walls, the inverse square law is very important, and you should never raise the lights higher than the manufacturer’s recommendations. Moving the lights too high in this case greatly reduces light intensity and yield.

REFLECTIVE WALLS

While the inverse square law applies to any light – these changes drastically when you use reflective walls. Reflective walls bounce the light back to your plants and greatly reduce the light loss from moving the lights higher. So, when using reflective walls in a grow room or grow tent, it is possible to place the lights much higher without losing a large percentage of the light.

If you have efficient reflective walls – going higher is normally better than lower regardless of which LEDs you are using. With reflective walls, the light bounces from many different angles into the plant and you will get move even yields and deeper penetration into the canopy.

The distance between your LED lights and your plants is, in fact, an exact science. Seemingly minor adjustments make a huge difference when it comes to giving your plants the kind of light intensity that makes them flourish, without giving them so much that they burn and wither.

OVERLAPPING LIGHTS

In larger grows where there are many lights in the same room along with reflective walls, it is often more effective to puts the lights higher so that the is overlap between many lights. This means that each plant will get light from many angles and this will promote much better penetration into the canopy and better overall yield.

For professional installations, California Lightworks can prepare a computerized light plan which can present the best light orientation in any environment.

Understanding this, the inevitable question is: What is that exact right placement?

How Far To Place LED Lights From Plants In Each Stage Of Growth

Once again, it is important to understand that there is no universal rule for how far to place LED lights from plants in each phase of growth. Different manufacturers construct their LED lights in different ways. There are multiple details to take into consideration, such as the power and angle of individual LED diodes within a fixture and the use of lenses to reflect light downwards. The best way to get that perfect distance between the light and your canopy is to consult with the manufacturer.

The second thing to keep in mind is that the correct LED light placement changes for each stage of growth. If your LED is dimmable, you can use dimming to adjust the intensity of the light on the plant surface. If your LED is not dimmable, your only option is to change the hanging height. These examples aren’t hard-and-fast rules, so don’t follow them without the blessing of your light’s manufacturer. But just to give you a ballpark sense of what LED light placement generally looks like throughout the growth cycle:

LED Light Placement For Seedling Stage

Seedlings need the least intensity and most distance between the canopy and the lights. You may have the instinct to blast these little guys with high-intensity light to promote fast growth. The truth is, they’re young, vulnerable, and likelier to thrive with a gentler approach.

Vegetative Stage

In the vegetative stage, you want to get your LED lights closer to your plants. In general, plants in veg only need about half the light that they need in bloom. It follows that you could have up to twice the hanging height that you use in bloom.

Flowering Stage

It’s in the flowering stage that you really need the highest intensity. It is important to build in a “hardening off” phase as you move from veg to bloom. Slowly increase the intensity or lower the hanging height until you reach the manufacturers recommended height in bloom.

Again, these are general guidelines. Discuss the ideal distances with your manufacturer and keep an eye on your plants for signs that you’re overloading them. If your plants are getting too much light intensity, they’ll let you know.

Final thoughts

Keep in mind, led grow lights for indoor plants are a bit more diverse when it comes to intensities, spectrum, and recommended heights. Furthermore, not all grow light manufacturers use the same measurements to talk about their products' intensity. You might find lumens, lux, PAR, PPFD, and wattage equivalency. It's much harder to estimate appropriate distances between plants and fixtures.

Unlike an HID light, you cannot perform a hand-heat test with an LED fixture because it doesn't create enough heat. Hanging height comes down to sheer-light intensity, not so much heat.

The intensity of the light all comes down to the strength of the individual diodes and how much of that reaches the plants. Most lLED lands somewhere between 1W to 5W diode power. The lower the diode strength, the closer you can place the lights to the canopy. Other manufacturers may talk about PPFD or lux ratings, but the higher the rating, the farther away the lights must sit.