October 20, 2022

Spectrum (lighting) in Riverside, CA

What Is Light Spectrum?

The light spectrum is the range of waves within the electromagnetic spectrum that is visible to us as humans. Measured in nanometres (nm), the visible spectrum sits between 380nm to 750nm on the scale. This means the blue side (bottom) of the visible spectrum has a slightly shorter wavelength than the red side (top).

The sun radiates solar energy, of which a very small portion ends up reaching Earth. This is because the ozone layer absorbs and reflects back most of the damaging waves, enabling life to thrive. Waves that infiltrate the ozone layer are between 300nm - 1100nm, so the spectrum coming into the atmosphere is wider than we are able to see.

Beyond the visible light spectrum we have gamma waves, x rays, ultraviolet waves, infrared, microwaves and radio waves. Ultraviolet waves and infrared waves sit at either end of the visible spectrum meaning they are included in the wavelengths that penetrate the ozone. Both are beneficial for plants in some ways.

  • UVC (180 - 280nm) - Includes harmful ultraviolet waves that are blocked by the ozone layer. Causes serious burns.
  • UVB (280 - 315nm) - Can burn skin yet only small amounts reach earth. Higher altitude places will have higher levels of UVB.
  • UVA (315 - 400nm) - Always present in the atmosphere yet not visible. 95% of ultraviolet waves entering through the ozone are UVA.
  • Visible Light (380 - 750nm) - The range of the electromagnetic spectrum that we can see as color.
  • Infrared (700 - 1100nm) - Invisible to the human eye but can be felt as heat.

Why Light Spectrum Is Necessary

Cannabis plants need the right type of light to grow to their full capacity. Without the right spectrums of light, plants can underperform, growing small and producing low yields. Fortunately, indoor growing strategies have allowed us to mimic the most vital elements of the sunlight received by plants outdoors.

Outdoor plants receive the full spectrum of light offered by the sun. In the spring, the spectrum of light that filters through the atmosphere creates a bluish color. The blue spectra is what allows plants to produce strong foliage during the early stages of growth.

As the summer arrives, the sun is higher in the sky and more light passes through the atmosphere. By the time fall arrives the sun starts to dip, when the red spectrum is most prominent. Red wavelengths indicate the end of summer so plants grow flowers in an effort to pollinate before winter.

How Marijuana Plants React to Light

Marijuana plants can flourish well under blue and red lights provided they get the right spectra within the color band. By singling out these wavelengths, plants have easier access to the type of light they require. This is among the reasons why indoor plants can be grown smaller than outdoor plants, since they do not have to expand in search for the required spectra.

  • Blue (400 - 500nm) - Blue light is needed for plants to grow strong leaves and branches during its vegetative cycle. Providing large quantities of blue results in short, bushy plants, which can be useful for growers trying to prevent tall plants with long branches. Suggested for seedlings, especially if you are growing indoors.
  • Red/Infrared (620 - 750nm) - Red is important for expanding plant structure and promoting bud production. Naturally, plants use red light to identify when it is day or night. Small amounts of infrared make its way through the atmosphere during sunrise and sunset when wavelengths are longer. Cannabis plants grow taller under infrared until visible red becomes more direct.

Photoreceptors in a cannabis plant's leaves are continuously trying to understand the light spectrum surrounding them. Leaves will turn to face the light during the day. When there is no light cannabis plants save their energy by 'relaxing' their leaves, making them droop slightly. Photoreceptors do not really turn light into energy, which is more to do with photosynthesis.

How a marijuana plant reacts to light will also depend on the strain and where it comes from. Some genetics have been brought from high altitude areas where the light is more powerful and there is a higher presence of UVB rays. It has been argued that exposure to more UVB can enhance THC production, although this theory is inconclusive and needs to be investigated more.

Finest Spectrum to Grow Marijuana

It is difficult to say precisely which part of the color spectrum is best but a big part of it relates to the type of light your marijuana plants are grown under. Not all lights produce the same spectrum so choosing will depend on the outcomes you are trying to achieve. The main thing is that your garden has sufficient blue light during the vegetative cycle and sufficient red light for blooming.

You may be planning to grow indoors where you can have full control over the light. Or maybe you're considering trying some outdoor plants, much of which will be determined by the sun. Whichever you choose, make sure your plants receive a lot of light.

  • CFL (compact fluorescent light) lights are typically measured in Kelvin (K), which tells us the color temperature of a bulb. Cooler, blueish lights have a higher Kelvin reading (6000 - 6400k), whereas a CFL that looks red will have a lower reading (2800k).
  • LED (light emitting diode) - LEDs give off a narrow spectrum of light, either in a small band of blue or red. Red, blue and white LEDs are frequently merged to produce a 'full spectrum' emission that plants can understand for proper growth.
  • HPS (high pressure sodium) - Yellow/red light can be used throughout the grow cycle, but plants will grow taller with more spacing between internodes. Marijuana plants benefit from HPS lighting mainly in the flowering stage.

If you are cultivating outdoors, you can anticipate plants to grow larger than they would indoors because the spectrum is broader. Depending on where you live and the time of year, plants will react to the light in different ways.

The color spectrum of your grow light is important however if you want to produce decent harvests, the intensity is also necessary. The intensity of your light source plays a big role in plant growth and has to be powerful enough for plants to photosynthesise appropriately. If marijuana plants do not get sufficient light, it doesn't matter what spectrum they receive, because they will not have the ability to function.

For all the grow lighting supplies with the best and latest technology in Riverside, California, contact Grower’s Choice at 909-972-8419 or visit our website at Growersc.com for more information.


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