What is a spectrum?
Although natural light may look white to us, it is actually made up of many different colors. When we pass light through a prism, or see a rainbow, we can see the true face of sunlight. When light is refracted into its parts, we can see all the colors that make up that light.
Over the years, we’ve learned that plants actually make “decisions” about how to grow based on the spectrum they receive. Different spectra can change the way marijuana germinates, grows and even blossoms. Although there aren’t many options to change the spectrum of sunlight when growing outdoors, since many users now use plant growth lights, we have almost complete control over the spectrum when growing marijuana indoors!
What is the “optimal” spectrum for growing marijuana?
This is a big problem because each spectrum has its own unique effects, and some spectrum is more useful for cannabis growth than others, there is no “best” spectrum for cannabis growth, but users can choose the best spectrum for their own goals and growing space!
Why does the cannabis plant respond to the spectrum?
When grown outdoors in the sun, the spectrum received actually provides cannabis plants with a great deal of information about what is happening in the world around them. In spring and summer, more of the blue spectrum reaches the surface.
In summer, the plant responds to this bright direct light (with a lot of blue light component), indicating that it has many large leaves and short stems growing nutritionally. The plant tries to spread as much as it can and increase the mass of its leaves.
Blue Light – Plant growth lights with a higher percentage of blue light are often used in the plant growth stage, as they tend to make cannabis plants short and robust, with large, healthy leaves.
As autumn approaches, the sun begins to set in the sky. As a result, more of the light reaching plants falls within the red spectrum. More light in the red part of the spectrum indicates that the plant is coming to the end of summer and it’s time to adapt before winter. When the cannabis plant is exposed to a higher percentage of red light, it responds by growing a longer stem with more space between the leaves, and grows as high as it can into the best condition to start germinating and pollinating by wind!
Yellow/red light – Growth lights with lots of red are often used during flowering to encourage plants to grow (spread) and help promote budding. Under red light, plants may enter flowering more quickly than under blue light.
By tracking the ratio of colors in the spectrum, marijuana plants are able to “learn” what’s going on around them, thus helping the plant grow in the optimal way!
If you want to make plants short and leafy at the same time, it is recommended to use more blue spectral components of plant growth lights. By switching the plant to flowering, you can switch the lights to the parts of the marijuana that like more red and orange during flowering.
How much does spectrum affect plant growth?
The cannabis plant needs bright light, at least some red and blue, for it to grow properly. Although certainly not essential for healthy plant growth, it is considered a good form of selecting the appropriate spectrum of light to encourage you wish to grow during the vegetative and flowering period of the cannabis plant.
Keep in mind, however, that different strains will be affected differently by the spectrum. Some plants are barely affected, while others may react more strongly. It is important to remember that the changes caused by the spectrum are relatively small (such as stems tending to grow longer), and that many other factors can drive some of the same changes.
On the other hand, if a plant is given a lot of yellow light, it tends to last very short, because it gets so much light that it has enough blue and does not need to be tall. Because almost all growth lights emit a spectrum appropriate for healthy marijuana growth, in many ways the amount of light affects the plant much more than the spectrum.
How does an in-depth study of the spectrum change the way marijuana plants grow
Light is part of the electromagnetic spectrum, which includes not only the visible spectrum but also X-rays, gamma rays and infrared light. Plants respond to spectra through a process completely separate from photosynthesis called photomorphogenesis.
Plants have certain light sensors (photoreceptors) throughout the plant, which act like the “nose” of the plant to detect information about the spectrum. Just as humans use their sense of smell to help find good food, plants use spectral information to help them grow in a way that gets the maximum amount of light.