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Growing Crops with LED Sheet Lighting

Cannabis plants shine purple under violet LED lights.


Growing Crops with LED Sheet Lighting

Photo courtesy of Marijuana

LED technology has become widespread, with many encountering it on a daily basis. They’re bright, use little energy and produce little heat. There are many companies that specialize in LEDs and many of them offer custom sheets of LEDs that can be used as grow lights for cannabis.

These sheets of LEDs can be of any size or shape, but for growing purposes it’s best to have a uniform shape. A sheet of LEDs with dimensions of 2-by-4 feet will put out 5,200 lumens of light. A growing closet lined with 10 2-by-4-foot LED sheets will put out 52,000 lumens of light.

Traditional single-source lamps such as metal halide have always had the problem of scorching the tops of plants. They produce lots of heat and the light source is from only one direction, leaving the lower branches of plants to be light-starved and phototropic. LED sheet lighting is the solution to these problems.

By placing the light source in a 360-degree arrangement (including from the top), it helps to distribute light to all sections of the plant, resulting in copious growth and some couch glue grass after harvest.

Each panel requires only 60 watts of power. With 10 LED sheets lighting the grow area, that means lighting requirements will be only 600 watts. The heat generated by one of these sheets is negligible. With a fairly-light electrical load, it will be possible to position the LED sheets in places previously thought to be impossible.

Some LED manufacturers also offer a tuning module that varies the frequency of the light the LEDs are emitting, which allows for a change in the color of light the sheet is emitting. This ability to dial up a color is a boon for growers, as cannabis likes a white light during its foliage growth phase and a more orange light to ensure maximum flowering and budding.

Most growers use a metal halide lamp for the green foliage growth stage and a high-pressure sodium lamp for the flowering/budding stage. With this light-changing ability, it’s unnecessary to change out grow lights for each growing phase.

Setting up LED sheets is simple, as they’re fairly lightweight and made of tough plastic. Mounting to a simple wood frame is the easiest way to set up a grow area. Because these sheets are so light, it’s not necessary to use heavy duty mounting hardware to support the heavy ballast transformer that both metal halide and high-pressure sodium lamps require.

By utilizing the highest technology to grow crops, many get some welcome and surprising results. LED sheets are the way to go if an operation is in something such as a walk in closet or a portion of a basement. The entire setup is so light that it’s possible stack growing areas on top of each other. LEDs have come full circle and are now a viable option for lighting needs.

The easiest way to house green is to build a box to contain them. I made a simple 6-foot square cube to grow my crop in. This provides ample room to contain the lights, growing medium and fan. I started with a simple frame made of 2-by-4s and covered them with a thin plywood. Since it’s not necessary to build the bottom, only the walls and the ceiling will need to be covered.

In order to mount the lights, I used nuts and bolts instead of screws. This is because it’s not good to have sharp-ended screws protruding from the box. Also, since the walls of the box are made of thin plywood, it’s doubtful that the screws would hold the lights up for any length of time. They’d eventually strip through the hole, causing a light panel to drop onto the greens. There were six mounting holes in the LED sheets I was working with, so the total amount of nuts and bolts needed was 60. The bolts also required steel washers in order to stop the inside and outside portions of the nuts and bolts from pushing themselves through the thin plywood.

Wiring in the lights was a simple affair as well. The sheets came with a 10-foot length of 18-gauge wire. I purchased a 100-foot roll of the same gauge wire in order to span the length from the wires that came attached to the panels. Every wire was fee to a standard 8 cubic inch gang box. I wired everything in series/parallel.

Since most plants won’t grow over 4 or 5 feet, there will be some room to arrange the growing medium. Most people use pots of peat and perlite and this is fine. Pretty good buds this way can be grown in this way, there are better options.

The technique I’ve perfected utilizes pea gravel as the growing medium. The seeds are germinated in a one-inch square Rockwool cube. Once they’re about 3 inches high, they’re transferred from the sprouting area to the pea gravel. The pea gravel container is filled with nutrient solution until the buried Rockwool cube is just barely covered. This is where the plant will grow for the rest of its lifecycle.

Previous to filling the growing tray with Rockwool, I ran aquarium tubing along the bottom of the tray that had been punctured every 3 inches. This tubing was then attached to an aquarium aerator. The idea is to have the aerator bubble air through the pea gravel and growing medium. This super oxygenates the nutrient solution and also moves the liquid solution around so there are no stagnant parts of the tray that will make roots susceptible to mold or fungus.

This easy setup will have anyone producing some prime buds that will blow minds. The cost is minimal compared to the results and since the box is practically air-tight and doesn’t involve any kind of material that can be blown around by the fan, cleaning between crops will be simple and easy.

Have you used LED sheet lights to grow your crops? Tell us all about your growing techniques in the comments.

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