what is the best light to grow cannabis indoors

What is the best light to grow cannabis indoors

Cannabis plants grown by depthchargeseeds under an HLG 300 Quantum Board LED grow light (check out their Instagram profile!)

Best Way to Avoid Problems with LED grow lights: Keep them the right distance away!

3.) COB Style

Generally, your goal with LED panels should be 50-60 watts per square foot of grow space to get the best results.

LEDs are often compared to HPS grow lights and each type of grow light has pros and cons for cannabis growers. Here’s the quick summary to help you decide whether LEDs are a good fit for you, and you can also read more deeply into the differences between LED and HPS here.

LEDs vs Other Popular Cannabis Grow Lights

HLG 550 Quantum Board (R-Spec spectrum recommended)

What is the best light to grow cannabis indoors

ALWAYS ask for a light plan that shows an average light level in micromoles AND a uniformity average (hopefully above 90% uniformity). Most LEDs are a very directional source of lighting. If a crop is grown under lighting that is not uniform across your canopy but instead has “hot spots” and “dark spots” it will cause you trouble as the hot spots will use more water, evaporate water, absorb nutrients, etc. at a different rate of speed then the dark spots! To truly have an “apples to apples” comparison be sure to compare light plans with the same targeted light level in micromoles and close to the same average uniformity number. If a supplier cannot provide you with these numbers then it may not be someone you should be considering.

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To use the PL Light TopLED R/MB as an example: 320W fixture with PPF of 860 μmol is 2.7 μmol/J (860 / 320 = 2.6875) where the 1000W DE HPS has an output of 2100 μmol is 2.1 μmol/J (2100 / 1000 = 2.1). This is important because I have sat in many presentations, by LED manufacturers, who show how quickly they can hit a good ROI with their LED and use 1.85 μmol/j as their HPS comparison. They’re not lying about this but they are using the old single-ended screw in 1000w HPS lamp in the comparison. These lamps have an output of 1850 μmols at 1000w. But, it is an old technology only in use by small hobby grows these days. I have seen manufacturers use as low as 1.7 μmol/J for HPS which would be the equivalent to the end of life of the old HPS technology.

Light Planning

This is a big consideration to consider when comparing these technologies. There is no easy math to calculate an ROI for this but when comparing light plans from one source of light to another be sure to take into consideration the distance of the light source from the canopy.

LED technology has only been available on a commercial level in the horticultural industry for around three years. So realistically, they would only have had time to trial a limited number of spectrums that may yield good results for one or two strains/cultivars. We simply have not had the technology long enough to perform the testing needed!

When it comes to building an ROI comparing LED versus HPS be careful with results that are supplied by manufacturers of only one type of light source. I have seen manufacturers on both sides of the argument manipulate numbers to favor their specific light source. Below is an outline of things to look out for when receiving an ROI comparing lighting technologies:

Unpacking Existing Information

The bottom line that I can share with you, from my perspective where I get visibility to lots of opinions on the topic, see lots of sales and growth cycles, talk to lots of growers, is this: We are still in the investigative and development stage with LED technology in this sector.

Another area you should always do your own math on is the BTU calculation for your grow room. Yes, LEDs produce less heat than HPS and this can be the deciding factor. As the cost to cool your grow room can be one of your highest production costs. Your AC load is based on the amount of BTUs produced from your fixtures. This is simple math as 1 watt equals 3.412 BTUs. No matter what 1000w HPS fixture you use the BTUs from that fixture will be 3412!