Light is a salient part of growing cannabis indoors. Without the natural presence of the sun, cultivators are forced to create their own source of energy for the plants. This may seem like a drawback for some people, due to the high standards the sun has set for plant growth. But in the era of modern lighting systems, there are several ways to mimic and artificially manipulate the effects the sun has on cannabis using mounted luminaries.
“If you’re trying to keep plants short with lots of leafy growth, use grow lights that give off light in more of the blue spectrum during the beginning of your plant’s life. When it’s time to switch the plant to the flowering stage, you might switch the lights to something that has more of the reds and oranges that cannabis likes during the flowering stage,” explained Nebula Haze from Grow Weed Easy.
Light Spectrums and Colors
To understand how this works, it is first important to understand the mechanisms surrounding light and plant growth. Light is made up of different wavelengths and spectrums. These components vary in measurements, characteristics and effects on cannabis during various stages of the herb’s life cycle:
- Ultraviolet (10-400 nm): UVB bands said to increase THC levels in cannabis
- Blue (400-520 nm): Helps cannabis plants grow short with robust leaves
- Green (500-600 nm): Improves plant responses (stomatal control, phototropism, etc.)
- Red (630-660 nm): Promotes flowering and budding, helps cannabis plants grow tall
- Far Red (720-740 nm): Promotes flowering
Another factor that dictates the application of light colors during indoor growing operations is the overall objective of the cultivator. For instance, businesses that manufacture edibles may choose to maximize oil yields, making potency top priority. For such objectives, one could focus on improving resin and THC/CBD yields, as well as plant size. To achieve this, a mix of red and blue with a ratio of 70:30 during pre-flowering and flowering stages is effective, followed by doses of UVB bands to boost THC levels (in some cases, up to 30 percent!) during the latter stages of flowering.
When using artificial lighting systems, it is best to avoid using a single, dominant wavelength of light. This is because the sun actually uses a well-balanced formula of light that includes other wavelengths. Failing to meet these requirements could reduce the effectiveness of activating plant pigments that rely on dual wavelength peaks (e.g., chlorophyll a [430-662 nm] and chlorophyll b [453-642 nm]).
Grow Light Technologies
To create a well-balanced lighting system, you need an artificial light that produces a wide range of wavelengths necessary for plant growth. These days, many large-scale growers are using LEDs – due to their ability to reduce energy consumption by up to 70 percent, produce up to 16 million different combinations of RGB-based colors and extensive lifespan of 50,000+ hours. Furthermore, unlike metal halide, fluorescent and incandescent lamps, LEDs are reinforced with solid-state designs, which allows the luminaries to withstand rough treatment (no loose filaments).
Grow light LEDs typically come with multi-band features to accommodate the required light wavelengths needed for optimizing plant growth. These types of luminaries are also compact and extremely portable. “Since LEDs emit little to no heat, they can be mounted closer to plants than other lights, which makes LEDs the optimal choice for lighting in small contained places,” said Advanced LED Lights.