How to choose indoor cannabis grow lights

Indoor grow lights are known for facilitating large yields of high-quality cannabis and can help you take your harvest to the next level. But how do you begin to choose if you're just starting your indoor grow journey?

To help you choose the best grow lights for your indoor cannabis garden, Weedmaps tapped into the specialized knowledge of a team of experts from the Resource Innovation Institute (RII), a non-profit devoted to efficient cannabis agriculture in Portland, Oregon.

Why should I use indoor cannabis grow lights?

Indoor cannabis grow lights offer several benefits and cultivators have virtually endless options to choose from, according to Michael Zartarian, an engineer at Zartarian Engineering and the RII Technical Advisory Council. "We are living in the golden age of grow lights. There have never been so many high-quality options available to home and commercial growers," he said.

Some of the reasons he touts indoor grow lights are:

  • Cost-effectiveness 
  • Efficiency
  • Productivity
  • Safety
  • Standardized technology
  • Third-party testing and verification

What type of light is best for growing plants indoors?

"Generally, white light with a 'bright white' appearance is used for growing small and vegetative plants indoors," according to Gretchen Schimelpfenig, RII's Technical Director. Specifically, LED grow lights are the recommended type for indoor marijuana cultivators for the reasons listed in the section above. Enhanced organic compound expression is possible with LEDs, meaning growers may see enhanced cannabis properties. 

Bottom line: LED grow lights are the way to go. 

indoor marijuana cultivation lighting
LED grow lights are the recommended type for indoor marijuana cultivators.
Photo by: Gina Coleman/Weedmaps

Can any LED light be used as a grow light?

Technically, yes, any LED light can be used as a grow light. However, there are some that work better depending on the stage of growth that the cannabis plant has entered. Zartarian noted that any standard 150 watt LED white light bulb could adequately nurture a small cannabis plant in the early stages of life.

As the cannabis plant matures, its need for light will change. "As the plant gets bigger and matures into the flowering stage of its life, it requires much more light over a wider area to grow optimally. This is where high-power, purpose-built grow lights are needed to get the job done properly," explained Zartarian. In terms of what to look for, Schimelpfenig pointed out that growers can “trust third-party certifying organizations to test and validate the claims made by manufacturers."

Bottom line: Consider consulting the DesignLights Consortium's Horticultural Lighting Technical Requirements and Qualified Products Library to compare grow lights by wattage, spectral distribution, and manufacturer.

Do I need a special light to grow plants indoors?

Some plants, such as microgreens, may flourish under basic desk lamps, according to Zartarian. But cannabis plants need brighter and more consistent light to carry them into maturity. At the same time, cannabis plants need a so-called "dark period" during the flowering stage, but ample light is key throughout most of the marijuana plant life cycle.

indoor cannabis cultivation lights
Cannabis plants need specialized lighting solutions to support photosynthesis, and horticultural lighting products are designed to optimize plant development.
Photo by: Gina Coleman/Weedmaps

So, not just any light will do the job. "Yes, cannabis plants need specialized lighting solutions to support photosynthesis, and horticultural lighting products are designed to optimize plant development, unlike your office desk lamp," according to Schimelpfenig.

Bottom line: Investing in high-quality LED lights for your indoor garden may pay off in the long run. 

Are house lights good for plants?

Even if you no longer use incandescent or halogen bulbs and have opted for LED lighting, it is unlikely that the lights in your home will be sufficient for your cannabis plants. Schimelpfenig cited the simple reason that the lamps in your house are designed for human eyes, not marijuana plants.

"Since the needs of humans to see are different than the needs of plants to grow, lighting solutions in your house are not designed to provide the spectra plants need for photosynthesis, and many cultivars will not get the light they need to develop to their maximum potential," she elaborated.

Bottom line: Choosing an LED grow light specifically designed for plants is a reliable way to ensure an abundant harvest.

What is the average cost of indoor grow lights?

The cost of operating indoor grow lights varies depending on wattage and how much light you are shining on your plant through each growth stage. Since young plants require less light, energy costs are likely to be lower during this stage. In 2018, indoor grow lights at different stages of the cannabis life cycle cost the following on average:

Clone phase

  • 54-watt high-intensity discharge (HID) T5HO fluorescent tube: $5.20
  • 24-watt LED T5 tube: $25

Vegetative phase

  • 1,000-watt single-ended HID grow light: $278
  • 630-watt LED grow light: $1,524

Flowering phase

  • 1,000-watt double-ended HID grow light: $495
  • 630-watt LED grow light: $1,524

Bottom line on indoor cannabis grow lights

LED grow lights are relatively inexpensive, energy-efficient options that provide essential photosynthesis for the indoor cannabis garden.

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The information contained in this site is provided for informational purposes only, and should not be construed as medical or legal advice. This page was last updated on December 1, 2020.