Lumens Vs Micromoles

Before we get too far into this, there are a few terms that need to be broken down first:

September 24, 2015

Before we get too far into this, there are a few terms that need to be broken down first:

  • Photon: A quanta, or particle, of light
  • Micromole: a way to measure the amount of a substance, or in this case the number of photons passing through a target area, one micromole of light equals just over 62 quadrillion photons
  • Photosynthetically Active Radiation (PAR):  all radiation with a wavelength of 400nm-700nm that is used for photosynthesis
  • Photosynthetic Photon Flux Density (PPFD): a measurement of PAR; the number of photons falling on a given area in a given amount of time, typically measured in micromoles per square meter per second

Because plants have evolved over thousands of years using sunlight, their preferred spectrum for growing mimics the spectrum of sunlight, also known as full-spectrum light. Full-spectrum light includes wavelengths between 380 and 700 nanometers (nm). Nanometers measure wavelengths of light in billionths of a meter, the smaller the number, the shorter the wavelength. As stated above, plants have evolved to grow best with light within this spectrum, specifically light between 400 and 700nm; however, Cannabis also uses some Ultra-Violet (UV) components below 400nm for increased essential oil production and some Near Infra-Red (NIR) wavelengths above 700nm to help the plant compete with neighboring plants that may be shading it from the light source.

If you are growing indoors, it is important to mimic the plant’s preferred spectrum as closely as possible. But what’s the best way to ensure the proper spectrum for plant growth is being utilized? Most bulbs will tell you right on the box what spectrum the bulb is designed to emit.

However, it is not as easy as that. Another measurement is typically included that can be misleading: lumens. Lumens measure relative brightness as observed by humans.. While it may seem obvious that the brighter the light, the more light that is being put off, lumens are based on human perception and plants view light differently than humans.

Humans cannot see as much of the full-spectrum of light as easily as plants. In fact, the human eye is sensitive to light in the middle of the spectrum, 500-600nm, and is most equipped to use light at 550nm. As mentioned above, plants have a larger range of ideal spectrum, but they react most strongly to light at 400-460nm (blue spectrum) and 580-700nm (red spectrum). As you can see, the light plants prefer, for the most part, is not within the same range as the light humans prefer. This is why using a subjective measure of light, such as lumens, an ideal way to measure the amount of light reaching the plant canopy.

Another Way

Light that is useful for photosynthesis is not necessarily bright, it should be dense. Light given to plants should be measured in micromoles and PPFD (see definitions above) which describe the density of light on the target are, rather than the brightness. This provides a more accurate measurement of the amount of light available for photosynthesis.

Micromoles and PPFD are what actually cause plants to react to the light reaching them. As PPFD increases, the light that is reaching the plant is more dense, and thus actually provides more light for the plant to use for photosynthesis, creating larger plants. As a quantifiable measurement, PPFD is a better way to determine how much light plants are receiving than lumens.

Next time you shop for a light or reflector, be sure to ask about the PPFD it puts out. And remember, a bright light for humans is not necessarily a bright light for plants.

Contact Us

Ready to get started or learn more about how we can help your facility succeed? Fill out the form and a company representative will be in touch.

Area of Support*

Share:

Featured Articles

Challenges of Indoor Cannabis Grows vs. Sun-Grown Cannabis

Cannabis has a long history, once frowned upon and illegal, but now widely accepted. Indoor cultivation is prevalent, despite support for legalization and outdoor cultivation in 21 US states.

Is Indoor Cultivation Difficult?

Indoor cultivation requires precise control of artificial environments for successful leafy greens and cannabis growth. Facilities, lighting, and automation play crucial roles. Discover the pitfalls many growers find out too late.

Optimizing Cooling Efficiency: Exploring the Benefits of the 4-Pipe Chilled Water System

Discover the benefits of the 4-pipe chilled water system for optimizing cooling efficiency and maximizing energy savings in this informative guide.

Interview with Brandy Keen: Emerging from the Indoor Growing Dark Ages

In this episode of the Cannabis Equipment News Podcast, Brandy Keen, co-founder and senior technical advisor of Surna Cultivation Technologies, discusses her nearly 17 years of industry experience helping some 800 cultivators.

Dodging Downtime [Case Study]

TruGro turned to Surna to provide a grow room HVAC solution that was efficient and would keep them running reliably for years to come.

4 Ways to Maximize Grow Room Square Footage

Staying competitive means maximizing your available grow room space. Cannabis cultivators and indoor food producers who can increase yields without sacrificing product quality or adding square footage are on the path to increased ROI. Here are 4 ways you can maximize your commercial grow space.
Sign up to receive blogs and other news

Footer

© 2023 Surna. All rights reserved.
Surna
Scroll to Top
commercial indoor farm considerations and setup examples