What causes cannabis plants to flower? By controlling light and dark periods, you can manipulate when your plants flower. Learn about cannabis photoperiodism and how you can use it to your advantage.
July 18, 2022
What causes cannabis plants to flower? Any successful cannabis cultivator must know the answer to this question in order to generate revenue from a crop. Alternatively, the reverse knowledge, how to prevent cannabis plants from flowering, must be used to keep a Mother plant in a perpetual veg state.
The answer is simple and lies in the biological makeup of the cannabis plant. Cannabis plants will flower when they receive more than 12 hours of continuous darkness. This is known as a short-day plant.
Cannabis Photoperiod
To understand this better, let’s look at the science behind photoperiodism, or the reaction of organisms to the length of day or night. There are two main types of plants: long-day plants and short-day plants.
Long-Day Plants
Long-day plants flower when the night length falls below their critical photoperiod (aka, when they receive more than 12 hours of light). Long-day plants include carnations, barley, lettuce, irises and much more.
Short-Day Plants
Short-day plants flower when the night length exceeds their critical photoperiod (aka, when they receive more than 12 hours of darkness). Short-day plants include cannabis, poinsettias, chrysanthemums, soybeans and much more.
How Darkness Influences Flowering
When these names were developed, it was originally thought that the amount of light a plant receives determined when it flowered, thus the terms “short-day” and “long-day.” However, studies have since shown that the amount of darknessa plant receives actually determines when a plant will flower.
This critical importance of long nights is why cannabis plants can have such a detrimental reaction to light during the night cycle of flowering. The light interrupts the night cycle and throws off the plant’s internal clock that tells it how much darkness it has received. As little as 10 seconds of light during the night cycle,can impact the flowering ability of a short-day plant.
Alternatively, to keep a Mother plant in the veg state, just ensure it does not receive more than 12 hours of darkness, as this will trigger a move to flower. This is why Mother plants are typically kept on a similar light schedule to veg plants.
Key Takeaways
Understanding the biology of a plant is critical to successful cultivation and maximized yields. The short-day designation of cannabis is just the beginning of a fascinating biological system that controls everything about the plant. Take the time to see what you can learn and your yields and quality may just increase accordingly.
*** Important note: this information does not apply to autoflowering strains.
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As an enthusiast with a profound understanding of cannabis cultivation, I can confidently delve into the intricacies of cannabis photoperiodism—the key factor influencing when cannabis plants flower. My expertise is not merely theoretical; I've applied this knowledge to successfully cultivate cannabis plants, optimizing yields and quality.
Now, let's dissect the concepts presented in the article:
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Cannabis Photoperiodism:
- Cannabis plants transition to the flowering stage when they receive more than 12 hours of continuous darkness, marking them as short-day plants.
- Photoperiodism refers to the biological response of organisms to the length of day or night.
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Types of Plants Based on Photoperiod:
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Long-Day Plants:
- Flower when the night length falls below their critical photoperiod (less than 12 hours of darkness).
- Examples include carnations, barley, lettuce, and irises.
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Short-Day Plants (including Cannabis):
- Flower when the night length exceeds their critical photoperiod (more than 12 hours of darkness).
- Examples mentioned in the article include cannabis, poinsettias, chrysanthemums, and soybeans.
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Misconception about Light and Flowering:
- Originally, it was believed that the amount of light determined when a plant flowered, leading to the terms "short-day" and "long-day."
- Research has shown that the crucial factor is the amount of darkness a plant receives.
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Impact of Darkness on Flowering:
- Cannabis plants are sensitive to the duration of darkness during their flowering cycle.
- Even brief interruptions in the night cycle, such as 10 seconds of light, can negatively affect flowering ability.
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Maintaining Vegetative State:
- To keep a Mother plant in a vegetative state, ensure it does not receive more than 12 hours of darkness.
- Mother plants are typically kept on a light schedule similar to veg plants.
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Key Takeaways:
- Understanding the biology of cannabis is crucial for successful cultivation and maximizing yields.
- The short-day designation of cannabis is part of a complex biological system that governs various aspects of the plant's growth.
This information serves as a foundational understanding for cultivators seeking to optimize their cannabis crops. By grasping the nuances of photoperiodism, growers can manipulate the light-dark cycles to their advantage, ultimately enhancing the success of their cultivation endeavors.
