The debate over the effectiveness of implementing a 3-day dark period before harvesting cannabis plants is one that has intrigued and divided growers for years. The practice involves keeping the plants in complete darkness for several days before harvest, with the belief that this stress will lead to an increase in THC production. This technique, which some growers extend to 7 days or more, has been the subject of both anecdotal praise and skepticism. In this comprehensive exploration, we’ll examine the origins of this practice, the scientific rationale behind it, the potential risks and benefits, and whether it’s worth incorporating into your cultivation routine.

Aside from the major milestones in the cannabis plant’s life cycle, like the seedling, vegetative, and blooming phases, the plants also go through regular cycles relating to respiration, photosynthesis, and other metabolic activities. Terpenes and cannabinoids, the two most valuable active chemicals in the cannabis plant, a peak near the conclusion of the dark cycle and begin to decline as the light cycle proceeds. So, right before the sun rises, or when your grow lights turn on, is widely regarded as the optimal time of day to cut the plants down to optimize the terpene and cannabinoid content of your buds.

Understanding the Dark Period Before Harvest

The concept of a dark period before harvest is rooted in the idea of manipulating the plant’s natural life cycle to maximize its final cannabinoid output. During the dark period, typically lasting from 24 to 72 hours, growers deprive the cannabis plants of light entirely. This period is believed to mimic the natural environment as the growing season comes to an end, leading the plant to intensify its efforts to reproduce by increasing resin and cannabinoid production.

The dark period is considered a form of stress, and plants often react to stress by producing more trichomes—the small, resinous glands that contain THC and other cannabinoids. This response is thought to be a defence mechanism, where the plant produces more resin to protect its flowers from environmental stressors. However, the effectiveness of this technique, particularly regarding a significant increase in THC levels, remains a topic of debate among both amateur and expert growers.

The Science Behind Extended Darkness

To understand whether a dark period before harvest can truly increase THC levels, it’s essential to delve into the science of cannabis plant biology. Cannabis plants, like many other flowering plants, follow a photoperiod—a cycle of light and darkness that triggers different stages of growth, including flowering. As the plants near the end of their flowering stage, they are typically exposed to a consistent light schedule, usually 12 hours of light and 12 hours of darkness, to maintain the flowering cycle.

Do you need darkness before harvest with an autoflower? Note that autoflowers are non-photoperiod cannabis plants, therefore, consult a guide on autoflower light cycles before making any decisions here.

The theory behind extending the darkness before harvest is that it can further stress the plants, pushing them to produce more trichomes as a last-ditch effort to protect themselves. Trichomes contain THC (tetrahydrocannabinol), the psychoactive compound responsible for the “high” associated with cannabis, as well as other cannabinoids and terpenes that contribute to the plant’s aroma and flavor.

Research on plant stress and trichome production does suggest that environmental stressors—such as changes in light, temperature, and humidity—can influence cannabinoid production. However, the specific impact of prolonged darkness on THC levels is less clear. While some studies have shown that stress can lead to increased trichome density, conclusive evidence supporting a substantial increase in THC due to extended darkness is lacking.

The lack of robust scientific data has not deterred many growers from experimenting with this technique. The anecdotal evidence from growers who report increased potency after a dark period before harvest adds to the intrigue, though results can vary significantly depending on the strain, growing conditions, and individual plant characteristics.

Common dark period before harvest theories

Here are prevalent theories explaining the dark time before harvesting your cannabis;

Cannabis dark period main theories

1. One explanation why dark before harvest improves cannabis quality is that mild stress increases resin production in buds. Lowering the nighttime air temperature is another method to stress your plants in a (supposedly) beneficial way. Alternatively, you can cool the root zone by watering mature plants with ice-cold water. There could be some truth, so go ahead and try it.
2. According to another theory, such a reaction to prolonged darkness is an evolutionary mechanism. Here’s how it works: cannabis begins to flower as the nights grow longer and longer. This tells the plants to act quickly to produce seeds before winter. Unpollinated female plants continue to have more flowers in the hope that some will catch pollen.

Other theories

If the nights are not only long but also appear endless, producing more flowers. Such a reaction could not have evolved because no one in nature turns off the sun for several days.

3. According to another theory, sugars and starches travel from the above-ground part of a plant to the root zone at night and are stored there for future use. Now, sugars and starches need to improve the quality of the smoke.

However, they make it harsh and the taste unpleasant. Farmers slowly dry and cure their buds for several weeks to remove these unwanted substances (and chlorophyll). Conversely, you can do the same with the long dark period before harvest. At least partly.

4. Finally, there is this explanation, which is very good science. The level of cannabinoids and other components’ concentrations are known to fluctuate. It peaks at the end of the dark period (night), after which cannabinoids are partially degraded by light during the day. Cannabinoids protect cannabis flowers from the damaging effects of UV radiation.

They are naturally depleted, and plants slowly replenish them at night. So, the obvious option is to harvest your cannabis before the lights are on inside or at dawn outside. Some growers use shorter days and longer nights (for example, an 11/13 flowering light cycle). It’s also said to make cannabis more resinous, but experts are not sure it is true.

Lab results on the dark period before harvest

Many websites and forums mention research allegedly conducted by the Stichting Institute of Medical Cannabis (SIMM). It was one of two approved sellers of medical cannabis in Holland until it went bankrupt within a year or two*, thanks to an American activist named James Burton. According to stories, Burton and his colleagues reportedly conducted an intriguing experiment. They harvested half of the plants normally while leaving the other half in the dark for 72 hours.

Furthermore, when they tested the finished dried product, they discovered that the cannabinoid level in some strains was up to 30% higher than in their usual harvest counterparts. CBD and CBN levels were constant.

Darkness time before harvest and terpenes levels

During the dark cycle, the content of aromatic compounds in buds rises. During the day, some of the terpenes evaporate when the air warms and occasionally becomes hot. For this reason alone, it’s critical to drop daily temperatures by a few degrees throughout flowering, especially closer to harvest. Keep in mind that terpenes and flavonoids do more than make the smoke smell and taste better.

They also have an effect on the character of the high, which is known as the entourage effect. A few dark days before harvest naturally, lead to a higher concentration of terpenes in buds. Farmers who have kept their plants in a fully dark room for 24h-48h or longer have reported how strong the smell becomes.

Implementing the Dark Period: Techniques and Variations

If you’re considering experimenting with a dark period before harvest, it’s crucial to understand the different techniques and their potential outcomes. The duration of the dark period, the environmental conditions during this time, and the specific strain you’re growing all play a role in determining the success of this method.

1. 24 Hours of Darkness Before Harvest:

• The shortest of the dark periods, 24 hours of darkness is often seen as a conservative approach. Growers who opt for this duration believe it provides enough stress to potentially increase resin production without over-stressing the plant. This period is generally low-risk and is a good starting point for those new to the technique.

2. 48 Hours of Darkness Before Harvest:

• A more commonly practiced duration, 48 hours is considered the sweet spot by many growers. This period is long enough to potentially induce significant stress responses in the plant, which could lead to increased trichome production and higher THC levels. At the same time, it is short enough to minimize the risks of mold or other issues that can arise from extended periods without light.

3. 72 Hours of Darkness Before Harvest:

• The 72-hour dark period is favored by growers who are convinced that a longer duration is necessary to see noticeable increases in THC levels. This period is thought to give the plant ample time to react to the absence of light by boosting resin production, potentially resulting in a more potent harvest.

4. 7 Days of Darkness Before Harvest:

• The longest and most experimental of the dark periods, a full 7 days of darkness is practiced by a minority of growers who believe in its dramatic effects on THC levels. However, this approach is controversial due to the high risks involved, including the potential for mold development and significant plant stress, which could negatively impact the quality of the final product.

Potential Benefits of a Dark Period

The purported benefits of implementing a dark period before harvest largely revolve around the idea of increasing the potency and quality of the cannabis. These potential benefits include:

1. Increased THC Content:

• The primary reason growers experiment with a dark period is the belief that it will lead to higher THC levels. By stressing the plant, growers hope to encourage the plant to produce more trichomes, which contain THC. Some growers report noticeable increases in potency, though these reports are anecdotal.

2. Enhanced Resin Production:

• In addition to potentially increasing THC levels, the dark period may also boost overall resin production. More resin generally means a stickier, more potent bud with a stronger aroma and flavor profile, which is highly desirable in the final product.

3. Improved Flavor and Aroma:

• The increase in terpene production, which can accompany increased trichome density, may enhance the flavor and aroma of the buds. This is particularly important for strains prized for their unique sensory characteristics.

4. Final Push Before Harvest:

• Some growers believe that the dark period serves as a final push for the plant to mature, ripen, and maximize its cannabinoid and terpene production. This period can also be seen as a natural conclusion to the plant’s life cycle, mimicking the shorter days of autumn when cannabis plants would naturally be ready for harvest.

Risks and Drawbacks

While the potential benefits of a dark period before harvest are appealing, there are also significant risks and drawbacks to consider. These include:

1. Risk of Mold:

• One of the most significant risks associated with prolonged darkness is the development of mold, particularly in high-humidity environments. Mold can quickly ruin an entire crop, making it crucial to maintain a dry, well-ventilated environment if you choose to implement a dark period.

2. Excessive Stress on the Plant:

• While some stress can encourage trichome production, too much stress can be detrimental to the plant’s health. Excessive stress during the dark period could lead to reduced yields, lower quality buds, or even plant death if not carefully managed.

3. Inconsistent Results:

• The effectiveness of the dark period technique is inconsistent, with some growers reporting significant benefits and others seeing no noticeable difference. This inconsistency can make it difficult to predict the outcome and may not justify the risks involved.

4. Impact on Yield:

• In some cases, the stress induced by the dark period can negatively impact overall yield. Plants may produce less bud, or the buds may be less dense than they would have been without the dark period.

5. Strain Sensitivity:

• Not all cannabis strains respond the same way to stress. Some strains may handle the dark period well and produce more resin, while others may not tolerate the stress and could suffer as a result. Indica strains, for example, might be more robust in handling stress than sativa strains.

Environmental Considerations During the Dark Period

To minimize the risks associated with the dark period and maximize the potential benefits, it’s essential to control the environmental conditions during this time. Here are some key considerations:

1. Humidity Control:

• Maintaining low humidity levels (below 50%) during the dark period is crucial to prevent mold growth. Mold thrives in dark, damp conditions, and the extended period without light increases the risk. Using a dehumidifier or ensuring good air circulation can help mitigate this risk.

2. Temperature Regulation:

• Keep the temperature stable and within the optimal range for cannabis plants. Extreme fluctuations in temperature can add unnecessary stress and may contribute to the development of mold or other issues.

3. Air Circulation:

• Good air circulation is essential during the dark period to prevent moisture buildup. This will also ensure that the plants receive adequate airflow. Fans can help maintain air movement, but be careful not to create drafts that could stress the plants further.

4. Monitoring Trichomes:

• Regularly check the trichomes during the dark period using a magnifying glass or microscope. This will allow you to monitor the plant’s maturity and harvest at the optimal time. By doing this, you’re ensuring that you harvest with peak THC content.

Alternatives to the Dark Period

If the risks associated with dark periods seem too high, there are alternative methods to consider for increasing THC levels. Any success in this area should also improve overall bud quality.

These methods include:

1. Shocking Plants Before Harvest:

• Aside from the dark period, other stress-inducing techniques can help. These include reducing water or lowering temperatures. All of which can also potentially increase THC levels. These methods create stress that may push the plant to boost trichome production without the risks associated with prolonged darkness.

2. Water Deprivation:

• Some growers stop watering their plants a few days before harvest. This method can concentrate the plant’s cannabinoids and terpenes, potentially leading to a more potent final product. However, like the dark period, this method should be approached with caution to avoid over-stressing the plants.

3. Selective Light Spectrum Changes:

• Try to gradually change the light spectrum to more blue or UV light as the plant nears the end of its flowering stage. This can mimic the natural light conditions of late autumn. By doing this you’re signalling to the plant that the end of its life cycle is near. This can encourage increased resin production, similar to the dark period, but with less risk of mold or plant stress.

4. Cold Temperatures:

• Exposing plants to cooler temperatures during the last week of flowering can simulate the changing seasons. This can potentially increase the production of anthocyanins, which give buds their purple hues. On top of that it should also increase trichomes. This technique should be used carefully, as too much cold can also stress the plant.

What to do before harvesting your buds

Watch out for mold and bud rot

Ensure the soil is dry before leaving the cannabis in the dark before harvesting. Watering your plant before turning out the lights is a terrible idea. For starters, lesser humidity equals greater cannabinoids. Second, keeping both the medium and the air dry reduces the likelihood of mold and bud rot. Because you can only monitor your plants for a few days, take all measures if you want your crop to be completely protected.

Curing and drying in the dark

Trimming a plant and hanging it upside down in a dark closet to dry does not imply that the plant is dead. It has no roots, yet it is still alive, and the chemical reactions within it slow but continue. So, the concept of employing prolonged darkness to boost the quality of buds also applies here. When drying and curing your buds, never expose them to direct light. Complete darkness isn’t required, although it wouldn’t hurt.

Autoflowers in the dark before harvest

Given the enormous popularity of autoflower strains, it’s no surprise that people keep wondering if they can give their autoflowers a dark time before harvest. You certainly can. All of the preceding principles apply to any cannabis plant, even autos.

Other tips for cannabis pre-harvest preparation

When it comes to harvesting your plants, the time of day is one vital factor. As the days countdown to harvest, here are some things you may do to prepare.

Monitor the color of the trichomes

While there are a variety of indicators, such as yellowing fan leaves and the size/shape of your flower buds, many growers rely on the appearance of the trichomes to determine the best harvest time. Trichomes will appear foggy or milky when terpene and cannabinoid levels are optimal. Clear-looking trichomes are most likely still immature, whereas amber trichomes indicate that the chemicals inside are beginning to break down.

Choose whether you’ll be wet or dry trimming

You must trim cannabis plants once they have been harvested. It is time to decide whether you want to wet trim (trim before drying) or dry trim (trim after drying) your buds. Both have advantages and cons, and preparing ahead of time is essential for ensuring a smooth harvest process.

Flushing before harvesting

It’s common practice to stop feeding your cannabis plants a week or two before harvest, a method known as “flushing.” Flushing forces the plant to consume both the residual nutrients in the growth media and the nutrients stored in the plant. Excess nutrients in the plant at harvest time might result in a harsh and bitter end product.

Prepare harvesting and drying equipment

Prepare and keep everything you’ll need for harvest near reach. Consider the space and gear you’ll need for drying and curing and the right cannabis harvesting tools.

Darkness aids in the replenishment of terpenes in cannabis plants. Terpenes evaporate during the day. So, the early morning is the best time to harvest. And by extending the night before harvest to at least two days, you can (arguably) obtain more flavorful and potent buds.

The Grower’s Perspective: Experiences and Anecdotes

In the cannabis growing community, growers have reported different experiences with utilising this dark period technique. Some growers report that their buds are more potent and aromatic after a dark period. However some growers see little to no difference. The lack of scientific consensus means that much of the evidence is anecdotal, with personal experiences varying widely.

For example, growers of Indica-dominant strains often report better results with the dark period, as these strains are more accustomed to shorter days and may respond more positively to stress. On the other hand, growers of Sativa-dominant strains, which typically originate from equatorial regions with consistent light cycles, may find that their plants are less responsive to the dark period.

Some cultivators also emphasize the importance of timing when implementing the dark period. The consensus among many is that the plant should be in its final stage of maturity, with trichomes mostly cloudy and beginning to turn amber. If the dark period is started too early or too late, it may not have the desired effect, or worse, it could reduce the quality of the harvest.

Conclusion: Is the Dark Period Worth It?

The question of whether a dark period before harvest increases THC levels doesn’t have a definitive answer. While the technique has its proponents, the scientific evidence remains inconclusive, and results can vary significantly based on the strain, growing conditions, and duration of the dark period.

For growers who are curious and willing to experiment, the dark period offers an intriguing possibility for enhancing the potency and overall quality of their harvest. However, it’s important to approach this technique with caution, starting with shorter dark periods and closely monitoring environmental conditions to avoid the risks of mold and excessive stress.

Ultimately, the dark period is just one of many tools in a grower’s arsenal. Whether it becomes a regular part of your cultivation routine will depend on your specific growing conditions, the strains you cultivate, and your tolerance for experimentation. As with many aspects of cannabis cultivation, the best results often come from a combination of knowledge, experience, and careful observation.

The post Does a 3-Day Dark Period Before Harvest Increase THC? appeared first on Premium Cultivars.