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Growing Photosensitive Cannabis Indoors

Photosensitive Cannabis

Introduction to Photosensitive Cannabis

What is Photosensitive Cannabis?

Photosensitive cannabis refers to a variety of cannabis that respond to changes in light exposure. These plants use light as a signal to transition from one growth stage to another. Understanding the photosensitivity of cannabis is crucial for indoor growers, as it allows them to control the plant’s growth cycle by manipulating light exposure. Want to read about the science behind and the advantages of photosensitive Cannabis, read this article.

Importance of Light in Cannabis Growth

Light plays a pivotal role in the growth of cannabis plants. As photosensitive organisms, cannabis plants rely on light exposure to trigger essential biological processes. The amount of light a cannabis plant receives within a 24-hour period can significantly impact its growth and yield. Want to learn more about the essence of light in cannabis cultivation, read this guide.

Stages of Indoor Cannabis Growth


Light Requirements in Germination

During the 5 to 10-day germination stage, indoor cannabis plants thrive on abundant light, with a recommended photoperiod of 16 hours of light and 8 hours of darkness. Red-enriched light aids germination. Sufficient light is vital for successful seed germination in this phase. Cannabis seeds require a specific light spectrum to initiate germination, usually in the blue range (400-500 nm). Light sources with high color temperatures like metal halide or LED lights are preferred. Offering 18-24 hours of continuous light daily accelerates and enhances germination. Optimal light intensity and duration ensure ideal conditions for seedling development, establishing a solid foundation for vigorous indoor cannabis growth.


Light Requirements in Seedling Stage

The seedling stage of cannabis growth typically spans 2-3 weeks. During this critical period, providing a light cycle of 18 hours of light and 6 hours of darkness is recommended, simulating an extended summer day. Optimal lighting for the first 10-14 days is achieved with an LED blue light spectrum, which contributes to the development of robust and healthy leaves. By ensuring the appropriate light requirements during the seedling stage, cannabis plants receive the necessary energy to establish a strong foundation for subsequent growth phases.


Light Requirements in Vegetative Stage

The vegetative stage is a crucial period for cannabis plant growth, lasting approximately 3 to 16 weeks. During this stage, the plant experiences significant development. To support optimal growth, it is essential to provide full-spectrum light for 18 hours, followed by 6 hours of darkness. Specifically, blue-enriched light with a wavelength of around 450nm is highly recommended during this stage. By ensuring the right light conditions in the vegetative stage, cannabis plants can thrive and establish a strong framework, preparing them for the subsequent flowering phase.


Light Requirements in Flowering Stage

The flowering stage, which typically spans 8 to 11 weeks, is a critical phase in cannabis cultivation. To maximize flowering potential, a light cycle of 12 hours of full-spectrum light and 12 hours of darkness is advised. Specifically, incorporating the red light spectrum during this stage proves highly effective, leading to denser, resinous buds and accelerated growth. By providing the appropriate light conditions during the flowering stage, cultivators can optimize bud development, resin production, and overall yield, ultimately achieving the desired results for their cannabis plants.

Manipulating Cannabis Growth with Light

Role of Different Light Spectrums

The role of different light spectrums is crucial in manipulating cannabis growth. Each wavelength of light affects the plants differently depending on the growth stage. By carefully exposing the plants to specific durations of light and darkness, along with the appropriate photosynthetic active radiation (PAR) light spectrum, growers can stimulate growth and achieve a higher-quality yield. Understanding the impact of light spectrums allows for targeted control over plant development, optimizing various aspects of growth, such as flowering, resin production, and overall plant health.

Commercial LED Lighting for Cannabis Growers

When it comes to lighting, the choice of spectrum is paramount. Modern indoor grow light options, particularly LED lights, offer cannabis growers the flexibility to select the ideal light spectrum for their plants. LED lights can provide a tailored spectrum that matches the specific needs of each growth stage. This customization ensures that plants receive the optimal light wavelengths for photosynthesis and other biological processes, resulting in improved growth rates, increased yields, and enhanced overall plant performance. The use of commercial LED lighting systems empowers cannabis cultivators to achieve consistent and efficient growth throughout their cultivation cycles.


Growing photosensitive cannabis indoors requires a deep understanding of the plant’s growth cycle and its light requirements at each stage. By manipulating light exposure and spectrum, indoor growers can control the growth of the cannabis plant and optimize its yield and quality.


  1. What is photosensitive cannabis? Photosensitive cannabis refers to strains of cannabis that respond to changes in light exposure.
  2. Why is light important in cannabis growth? Light triggers essential biological processes in cannabis plants. The amount of light a cannabis plant receives within a 24-hour period can significantly impact its growth and yield.
  3. What is the recommended light exposure during the germination stage? During the germination stage, cannabis plants need 16 hours of light and 8 hours of darkness.
  4. What type of light is recommended during the vegetative stage? Blue enriched light, ideally at 450nm, is recommended during the vegetative stage.
  5. What type of light is recommended during the flowering stage? The use of the red light spectrum is incredibly effective during the flowering stage.