I am a beginning grower of cannabis. I am really struggling to find out which LED light is best for a 4' by 4' inside grow area? What would be your recommendations?

Thank you for your question. It can be difficult to determine which horticultural LED lighting system is best for an indoor cannabis garden. Artificial horticultural LED lighting is a competitive market, boasting many products and this can be overwhelming for a new grower. LED lighting systems are very popular among growers due to their low heat signature and relatively efficient light output. LED technology allows growers to maximize the amount of PAR (photosynthetically active radiation), or usable light energy, for their plants and do so without creating an abundance of heat. To compare LED lighting systems, it’s helpful to understand the different types of LEDs used for horticulture.

There are two types of LEDs used for horticultural lighting systems: surface mount and chip-on-board (COB). Surface mount are the most common and what most people would associate with an LED system. Surface-mount LEDs come in low-, mid-, and high-power options. Mid- or high-power diodes are used for horticultural purposes, as the low-power surface mounts are too weak to get results in the garden. Mid-power surface mount LEDs for horticulture are cost efficient and have a power range of one watt or less for each diode. High-power surface mount LEDs for horticulture are more expensive and typically have a power range of three to five watts per diode. Chip-on-board LEDs are essentially multiple LED chips adhered to a substrate which produces a sort of LED array. Both surface-mount and COB LED systems can be effective for growing plants.

The biggest determining factor for choosing the right LED for your grow space is the amount of light energy available to the plants. This is most accurately done by measuring the photosynthetic photon flux density (PPFD) at your garden’s plant canopy. PPFD is the amount of light photons that hit a surface (in this case your plant canopy) during a one second duration. This can be measured in units known as micro-moles. To take it a step further, you can look at the lighting system’s daily light integral (DLI). The DLI is the calculation of your PPFD throughout one day (or light cycle). Cannabis growers will shoot for at least 40 moles (one mole equals 1,000,000 micro-moles) of light per light cycle. Beyond 40 moles per day, most cannabis gardens experience a point of diminishing returns.

For most beginners, PPFD, micro-moles, moles, and DLI are a bit overwhelming. Although these measurements can help professionals maximize their returns, hobbyist growers can adequately choose a LED lighting system for their gardens based on the actual wattage of the lighting system. A good rule of thumb is to incorporate at least 32 watts per square foot of growing space. Keep in mind this refers to the actual wattage of the unit, not the amount of watts the LED manufacturer claims the unit replaces. For example, in a 4x4-foot garden (16 square feet), you would want to have an LED lighting system with an output of at least 512 watts. This will provide enough energy for your cannabis plants to mature and flower effectively in that given space. I hope this answers your question.

Keep on Growing,
Lee G. Lyzit