As LED lighting continues to improve, the list of growers who benefit from these advances in technology grows as well. No longer is it just indoor grow room cultivators that can reap the rewards of powerful grow lighting, but also the savvy greenhouse operators looking to join the movement away from inefficient HID systems. Those looking to make the switch should keep a few key things in mind when purchasing a light for their greenhouse in order to share in the bounty that so many LED users have been enjoying.
Small Size
It’s very important that a grow light designed for a greenhouse is small in size. Greenhouses rely on natural sunlight first and foremost, so any additional lighting must not block the path of the sunlight hitting the plants. That’s why greenhouse lights like the Pleiades and Cobra by Fohse are lauded for their small design. The slim profile of the light was designed to line the trusses of a greenhouse, fitting in perfectly without blocking the windows. Because it casts no additional shadows, it is the perfect supplemental light source for a greenhouse or hoop house, as it provides uniform light across the entire canopy.
Large Output
In any grow room, whether a greenhouse or an indoor set up, photon density is key to getting a larger yield. Greater photon density leads to more carbon assimilation in the plant, which means that the plant will pack on more biomass when exposed to increasing light levels. Even a greenhouse light will have more of an impact if loaded with an abundance of diodes.
Because the nature of greenhouse lighting is supplemental, some lighting manufacturers may steer buyers away from powerful lights. However, growers should not be dissuaded from purchasing powerful lights because they think they don’t need the extra juice. Cannabis is a light hungry crop. While other plants experience diminishing returns at higher light levels, cannabis can take more light without experiencing the same growing plateaus. At certain growing stages, the limit to how much light a cannabis plant can take is still unknown. On top of that, a powerful light run at a lower intensity will always outlast a lower intensity light running at full power.
The O6i by Fohse packs more photons into each footprint than any other greenhouse light on the market, and is paired with a spectral distribution ideal for complimenting natural sunlight. The photon output of the O6i is actually 50% greater than a 1000W Double Ended High Pressure Sodium light, and with a 40% higher efficacy, it doesn’t use more energy to deliver more light.
SEE HOW BELUSHI’S FARM GREW MORE WITH THE FOHSE O6i:
Wide Footprint
Because of the limited ceiling space in a greenhouse, a greenhouse grow light should be able to cast a wide footprint of light in order to deliver more light to more of the canopy. This wide range is necessary in order to hit every plant in the room without the need for a large number of fixtures. In order to cast a wide spotlight, the Fohse O6i forgoes additional lenses over the diodes in order to utilize the 180º output that diodes naturally have. Combined with the reflective nature of greenhouse walls, this allows the high amount of supplemental light to cast a wide footprint and flood the greenhouse with an even diffusion of supplemental light, and do so using fewer fixtures. 
Heat Management
Greenhouses are designed to be hot enough on their own… that’s why we named the Greenhouse Effect after them. So, an HPS system, known for emitting tons of infrared heat, may not be ideal for greenhouse growers. The immense heat they radiate can be a headache to deal with, raising the cost of air conditioning and requiring more water to deal with the dry conditions they create.
While LEDs are known for being better at dealing with heat, not all LED grow lights are created equal. An LED that ineffectively manages its heat can still raise ambient air temperature, and, if too close to the plants, can raise their temperatures to unhealthy levels. It’s also important to note that operating at a higher heat will result in the light taking a serious hit to its efficiency. Cool diodes run more efficiently, using less energy to create more light, so there is a tremendous incentive to buy a light that manages heat effectively, keeping diodes cool, and also keeping the heat the light creates at a level plants can tolerate.
The Fohse O6i is a perfect example of a light that utilizes both passive and active cooling in order to maintain low temperatures and efficient output. First, two heat sinks attached to the light increase its surface area, drawing heat away from the source and into the conductive surface of its aircraft grade aluminum fins. These fins are then actively cooled by two hyper-efficient, variable speed fans, which wick away heat whenever it becomes too much. This effectively keeps the LEDs cool and running efficiently.
High IP Rating
To be frank, greenhouses are a bit more rustic than their sterile grow room counterparts, known for high moisture, and a bit more of a natural feel. Having a light that can withstand not only moisture, but dust, debris, bugs, mold and bacteria is paramount to maintaining a healthy crop. Growers looking for a greenhouse light should be sure to check the Ingress Protection (IP) rating of their prospective light purchases. This double digit number signifies how well the light is protected by water and debris.
The first number indicates how well a light is protected from particles on a scale from 1-6. In the grow light world, the particles you want to be protected against can be miniscule, from aphids to fungal spores, and even microscopic bacteria. If a light has a first number below 6, it is vulnerable to dust, and anything smaller, including moisture, bacteria, and fungal spores, could still sneak in. Only at a 6 in the IP ratings is a light certified to be airtight, and protected from intruders of all kinds.
The second number indicates how well a light is protected from water on a scale from 1-8. From 1-6, the IP ratings indicate that “limited ingress is permitted.” What that means is that water can still seep through the protective casing of the light and into the circuitry of the device. Only ratings 7 and 8 indicate that it is safe from the ingress of water, and that includes full submersion.
SEE THE O6i IP RATING:
Because of the invasive nature of moisture, bacteria, bugs and mold, the only way to make sure you are purchasing a light that is safe to use in the greenhouse is to find a light with an IP rating of 67-68. This rating guarantees that your light will not play host to any of nature’s crop saboteurs.
