The Best LEDs: 6 Things To Consider When Purchasing LEDs

Contrary to what some LED Grow-light retailers might tell you, no two LEDs are the same. Within a single company, there could be multiple models they sell, each designed for specific purposes, and to achieve a specific result. Expand the scope from within a single company to the free market, and the amount of variations multiply. LEDs for greenhouses, grow-ops, single plants, lamps for keeping plants in vegetative state, and lamps to make them flower; each category a battleground between competing manufacturers. For a layperson, it’s almost impossible to pick a side, at least without the right weapon. However, when armed with enough knowledge, the average grower can distinguish key features, statistics, and details that separate a regular LED grow light from a top-of-the-line powerhouse.

Resistant to dust/ debris/ bacteria

The adage is age-old: the best offense is a good defense. In the cannabis cultivation sphere, there are plenty of foes lobbing relentless attacks on not only your plants but the equipment that aids their growth. Aphids that munch on plants look for places to hide, and a poorly sealed light is a prime spot. Plant-killing bacteria are hungry for hospitable surfaces. Mold and mildew lurk in spaces where water settles, and a hanging light gives them a nice home as they wait for an opportunity to bloom below. Lights without proper protection become hosts to these critters and more.

If you want to see if a grow light has good protection, look no further than its Ingress Protection rating. The rating is made up of two numbers. The first number rates how protected a light is from solids, like dust, debris, etc., on a scale from 1-6. The second number rates how protected a light is from liquids on a scale from 1-8. At 8, a light should be able to be submerged in high-pressure water environments for a long period of time. Typically, lights with 8 as their second number are specifically designed to grow aquatic plants that are adapted to live in highly pressurized environments like the ocean floor. The next step down, a light with a 7 for its second number, can be submerged in water for 30 minutes. While a light with a 6 is protected from jets of water, the constant pressures of a moist environment can slip through the cracks, and an ingress protection from full submersion is the only way to guarantee that your lights are safe, especially when cleaning. Lights that are truly protected from water ingress can be cleaned without ever being lowered and disconnected. Most growers operating high IP rated lights just use the pressure of a normal garden hose attachment to hose down their fixtures post-harvest.

Able to Increase Intensity without Moving The Light

Growers may find that the lights they purchase aren’t able to deliver the photons they produce directly to the plant. Often, lights will have a high PPF figure, which indicates the amount of photos they produce, but in practice, have a low PPFD, which indicates how many photons actually gets to the plant. Even at full intensity! If the light is already operating at max output, one of the only ways to deliver more photons to the plant is to move the light closer to the canopy. Now, as the plant grows, the light will need to be raised to maintain consistent output as the plant grows, so that the heat from the light doesn’t damage the growing plant. This can be accomplished either by repeatedly making laborious adjustments to the light as the plant gets taller, or installing expensive rope and pulley systems to adjust the distance from light to plant.

The added ability to increase or decrease the light’s intensity in fixed intervals as little as 1% is what we like to call power ramping. This feature allowed for a high-powered light to incrementally get more or less intense in its output to match the plant’s needs at every growth stage, so growers no longer needed to adjust their lights with an expensive lift system or repetitive and costly labor. With Fohse lighting, it’s our secret sauce. With a simple swipe on your control screen, you can take the light from 30% of its max power all the way to 100%. This has the added benefit of allowing growers to run their lights more efficiently. They don’t need to be at 100% all the time and running them that intensely at all times will negatively impact how efficiently the light performs, how long it will last, and how hot it will get. 

Abundance of Diodes

This may seem obvious, but the more diodes a light has the more light it can deliver efficiently. Just like how a room with two lights is brighter than the same room with one, a light with a ton of diodes is going to be brighter than a light with less. Now, lights can have the same output and have different amounts of diodes, but the light with more diodes will work less to achieve the same result, meaning it will cost less to run, and run more efficiently, converting energy into light for less cost. This is because having more diodes allows for the diodes to be run at lower intensity, which in turn means that they don’t get as hot. At lower temperatures, diodes perform better, and for longer, fading at a slower rate than diodes that have been forced to run at high outputs. Plus, the grow light with more diodes is going to have a greater potential output, which is especially effective for light-hungry plants like cannabis.

Proper heat distribution

LEDs can get hot if not properly built, and as stated above, this has big ramifications. A great LED grow light will have systems in place to dissipate heat and keep the light cool and operating efficiently. Heat dissipation is handled in a couple of ways that can also impact a light’s performance. Some lights will add some form of an air conditioning system to the light. While this will cool the light down, it will require energy to do so. That can come out of the light, lowering its efficiency, or require a separate power source, which will raise overall energy consumption, and the cost of powering the system.

There are other heat management solutions, like heat sinks, that can dissipate heat without using energy. Heat Sinks are added to a fixture to increase its surface area. On the Fohse A3i, the addition of finned heat sinks add over 16,000 square inches of heat-dissipating surface area. By making the light larger, these effectively draw heat from the diodes and spread it across the aluminum fins through conductive heat transfer. The shape of the fins then allows air to pass through the sinks and take that heat away from the entire fixture through convection. Since this whole process is done without power, there is no additional charge to the budget, or loss of efficiency to the light.

Read more about the relationship between light and nutrient uptake in plants. 

Lensing

Not all the light emitted by a grow-light reaches the plant. This is an undeniable fact of light, it dissipates, it gets absorbed, it reflects. That’s why

 there are two different figures that are important to the output of a grow light. First, PPF, which measures how many PAR Photons a light emits, and PPFD, which measures how many of those emitted photons are received by the plant. Even if a light has a high PPF, it doesn’t mean the light will reach the plant. Some lights, like HIDs, emit light at an angle of almost 360º. Because of the shape of diodes and how they are mounted they only emit light at 180º, which is already a better starting point. There is no light being lost to the ceiling, like with HID which requires a reflector hood, but still, light is spilling to the left and right instead of straight down to the plant.

Clever LED manufacturers will apply a secondary optic, like a lens, over the diode, decreasing the angle of the light emitted. While a decrease may sound like a bad thing, in the lighting world it means the light is actually more focused. Whatever light that was being lost to the sides is being redirected, adding its strength to the light that was already headed towards the plants.

Adding the lens reduces the amount of photons that are being emitted by the lamp by a tiny amount, negligibly decreasing the PPF of the light. However, the light that was not hitting the plants will be redirected, increasing the PPFD figures of the light by a substantial amount. So, while it may seem like the light’s performance is being negatively impacted, the amount of light the plant is receiving is actually increased!

At the end of the day, the PPFD efficiency of a grow light matters far more than its PPF efficacy.

PAR spectrum output

Plants require a specific type of radiation to begin photosynthesis, known as photosynthetically active radiation, which is within the same range of light we can see. Plants consume all the colors we perceive, from red to violet, and each color provides specific benefits to the plant. In nature, the colors the plants consume change with the seasons. As the earth spins around the sun, the angle at which sunlight hits the earth alters the ratio of colors, which cues plants to alter how they grow to prepare for the summer or the winter. These changes taken from sunlight’s cues are known as photomorphogenic responses.

In a grow room, in order to mimic sunlight, you need lights that produce this full range of light. You also need lights that can change the ratios at which the lights emit specific colors so you can get the plant to grow and flower. To do so, an LED light needs diodes that emit a range of colors.

Some LEDs will be made with only red diodes, a process we refer to as Red Loading. With a longer wavelength, red is an easier color to emit, so it takes less energy. As red is in the PAR spectrum, it will seem as if the light is emitting tons of light that the plant would love. But without the other colors, the plant won’t be getting the full diet it requires to produce not only chlorophyll, but other secondary photosynthetic chemicals that add color and quality to cannabis.

That’s the difference between a good and a great LED. A good LED will check the boxes, sure. It will emit light, it won’t be as hot as an HID system, and it will save you money on your energy bill. But a great LED will last long, run well, provide more control, better intensity, more efficiency, and increase not only the quantity of your yield but the quality, as well.

In closing, remember the old adage “you get what you pay for.” When building out an artificial grow environment, the first and most important problem to solve is sunlight. It’s also the most expensive problem to solve. The temptation to cut corners and save on costs is strong, but that will only create more problems for you down the road. When it comes to the most important investment in your grow environment, it’s better to buy right the first time… and buy only once.