A favorable yield is one of the most important aspects of running a marijuana business. You want to ensure the proper growth of cannabis plants once they reach the dispensary or the consumer. When growing marijuana plants, your success often depends on one crucial factor — lighting. 

Light plays a crucial role in the quantity and quality of bud growth. A full-color light spectrum enables growers to maximize plants’ budding abilities. Read on to learn how various lights can boost your yield. 

Stages of Cannabis Growth

The cannabis growth cycle has four stages: seed germination, seedling, vegetative, and flowering. Using the correct lights plays a critical role during the last two stages of the sequence.

Vegetative Stage

Keep in mind that cannabis plants are sensitive to light, so it’s necessary to make adjustments to match natural light sources. We recommend learning about the cannabis light cycle to produce more high-quality buds.

The vegetative stage is when the leaves and stems begin growing. During this stage, you can manipulate plant lights for a more favorable result. Since cannabis does not produce any buds, it’s essential to control its size and shape.

Our cannabis pros suggest keeping the plants under growing light for at least 18 hours during the vegetative stage. However, if you prefer growing your plants as big as possible, it’s best to keep them under a 24-hour indoor light. 

Flowering Stage

Remember, cannabis plants don’t develop flowers until they receive 12 hours of continuous darkness. They need at least 12 hours of darkness exposure to move from the vegetative to the flowering stage.


During the vegetative state, growers typically prefer indoor plants. They start with 12 hours of darkness until the plants reach their ideal shape and size. We recommend caring for such plants from four to eight weeks under an 18-hour or 24-hour light period. 

Outdoor plants begin developing flowers when days become shorter because they get at least 12 hours of total darkness. It’s essential to emulate this pattern to achieve desired results for indoor plants.


If you plan to grow cannabis plants outside, let nature take its course. During this period, the plants start producing flowers on their own. Cannabis plants do not stop growing or developing flowers during this phase. After some time, these plants experience a growth spurt in height and shape. 

Do not expose your plants to light during the 12 hours of darkness. Exposure to any light source — including floodlights and street lights — can disrupt the flowering process. 

Image by NickyPe from Pixabay

Light Spectrum and Cannabis Growth

Below are various light colors that can impact plant growth. Each color along the spectrum has a wavelength responsible for what that the human eye sees. Understanding how different lights can affect your plants will help you make sound choices for their growth.

Sunlight provides plants with the entire light spectrum and changes along with seasons. The goal of using lights is to emulate these seasonal wavelengths. In the summer, sunlight naturally radiates cool colors like blue. During seasons with shorter days, the sun gives off more warm colors like red.

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Ultraviolet Light

With a wavelength ranging from 10nm to 400nm, ultraviolet light can either make or break a cannabis plant. It provides benefits to cannabis plants, but too much of it can damage them. When it comes to cannabis plants, there are two types of ultraviolet light to consider. These are UV-A and UV-B, ranging from 280-315nm and 315-400nm respectively. 

Experts consider UV-A harmful, but plants can naturally defend themselves against these lights. Plants may find it more difficult to fend off higher UV-A concentrations.

On the other hand, UV-B causes less harm. When used correctly, UV-B lights may prove beneficial for plant growth. We recommend feeding plants with substantial amounts of UV-B light to encourage robust growth and flavor. 

Blue Light

Blue light provides plants with many benefits that UV does — without the harmful side effects. It is milder compared to UV, making it ideal for plant growth. 

With wavelengths ranging from 450nm and 495nm, blue light plays a critical role in total yield output.

It’s best to use these lights during the sprout and vegetative stage to enhance compactness. Without this light, cannabis plants will experience difficulties in supporting flowers. 

We recommend using blue LED chips or cool white fluorescent bulbs to produce blue lights. 

Red Light

With a wavelength ranging from 620nm to 750nm, red light is the last visible color on the light spectrum. 

Red light is essential during photosynthesis and propels flowering, making growers switch to a brighter source once plants begin budding. Doing so boosts germination and prevents plants from becoming elongated. 

Unlike blue light, red LED chips are some of the least expensive on the market. For best results, try combining red and blue lights. 

Green Light

A green light has a wavelength range of 495nm to 570nm. Studies show that green light can effectively penetrate leaves, unlike blue and red that the outer leaf layers absorb. We recommend this light to help lower layers produce yield.

Light and dark cycles easily affect cannabis plants, and any light source at night can trick them into flowering. However, green lights don’t have this effect on plants. We recommend them for those who prefer caring for their plants at night.

Violet Light

Violet light is at the lower end of the light spectrum and has a wavelength range between 380nm and 450nm. It has a shorter wavelength and higher energy concentration than most lights, making it an ideal secondary light source. We recommend using it to improve vegetation and taste. 

Yellow Light

Yellow light has a wavelength ranging from 570nm to 590nm. This light promotes budding, making it helpful during the flowering stage. However, yellow light has minimal effect on overall plant growth.

Image by NickyPe from Pixabay

Grow The Best Cannabis Plants

Growing cannabis plants indoors involves emulating ideal outdoor conditions for photosynthesis and bud formation. It’s necessary to understand how various light wavelengths affect a plant’s growth. This guide should help you choose the best lights that can lead to a better yield.

Do you want to read more articles like this one? Whether you’re looking for information on cannabis licenses or product reviews in your state, TNMNews.com has it all. 

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