The Effects of Light Intensity on Plants


When growing marijuana indoors, you need to control the right environmental conditions for the healthy growth of the plants and the final harvest of high-quality cannabis buds. The yield and quality of cannabis are affected by many factors, among which light intensity is an important environmental factor. So, how does light intensity affect the growth and development of plants? This article will explain it to you one by one.

the Relationship between Light Intensity and the Growth and Development of Cannabis

Illumination intensity refers to the luminous flux of visible light per unit area, usually expressed by PPFD (photosynthetic photon flux density), and the unit is micromol/square meter/second (μmol/m2/s). PPFD reflects the amount of light that plant leaves can absorb and is also an important factor affecting plant photosynthesis and growth. Different plants have different requirements for PPFD. Generally speaking, plants with high light requirements need higher PPFD, while plants with low light requirements need lower PPFD.

What impact does PPFD have on the yield and quality of cannabis grown indoors? – The Effects of light intensity on plants

Generally speaking, the higher the PPFD, the higher the yield and quality of the cannabis. Cannabis is a plant with high light requirements, and it can accept PPFD up to 2000 μmol/m2/s in a natural environment. High-intensity light can promote cannabis branching, flower bud formation, and resin secretion, thereby improving cannabis weight, density, aroma, and potency. However, it is not that the higher the PPFD, the better, because too high light intensity can also bring some negative effects to cannabis, such as causing leaves to turn yellow, wither, burn, or fall off, and reduce the ability of cannabis to resist diseases and insect pests.

According to several studies, cannabis yield increases linearly with light intensity up to at least 1500 μmol/m2/s, twice the light intensity most commonly used by cannabis growers. This means that for every 1% increase in PPFD, there is a proportional 1% increase in production. For example, if you increase the PPFD from 400 μmol/m2/s to 800 μmol/m2/s, the expected harvest will double.

the Relationship between the Light Intensity and the Photosynthesis of Cannabis

The light intensity can affect the potency of cannabis. Studies have shown that high light intensity increases the concentration of cannabinoids and terpenes in cannabis flowers. Because high light intensities induce a stress response in plants that triggers the synthesis of these compounds, high light intensities also increase the density and size of trichomes.

Light intensity determines the ability of plants to photosynthesize. The study found that the rate of photosynthesis in cannabis leaves increases with light intensity, which boosts plant growth. The rate of photosynthesis begins to drop when light intensity exceeds a certain point, which can be caused by factors such as photoinhibition and the inability to effectively manage airflow, carbon dioxide delivery, or maintain desired temperature and humidity setpoints. These findings suggest that there is an optimal light intensity range for the maximum rate of photosynthesis in cannabis plants and is related to airflow, carbon dioxide, temperature, humidity, and other factors.

In conclusion, light intensity (PPFD) is one of the important factors affecting the yield and quality of cannabis grown indoors. Indoor growers should choose the right lighting system and PPFD level for optimal planting results based on their goals and conditions.

As always if you have any questions you can message our Instagram or Facebook and we’ll be glad to help you out! We’re happy you’re on this journey and we want to help in any way we can.

Subscribe to the VIVOSUN newsletter for growing tips, grower stories, and special offers, and get 12% off your first order!

We love the new VIVOSUN Smart Grow System and we are certain that you too will love it once you try it.

And join our Facebook farmer’s community for even more exclusive contests and prizes!

Download VIVOSUN App to get 15% off and explore more information!