Do Autoflower Cannabis Plants Need Complete Darkness

Are you ready to embark on a fantastic voyage through the mystical world of auto cannabis plants? Let’s dive into the depths of the dark, unraveling the enigma of do autoflowers need darkness and exploring the perfect light schedules for these green treasures.

Do Autoflower Cannabis Plants Need Complete Darkness
John Kees

Author: John Kees

Publish Date: July 13, 2023
Last Update Date: September 13, 2023

What is Autoflowering Cannabis Plant

What is Autoflower Cannabis Plant

Born from the union of Cannabis ruderalis, the wild child of the cannabis family, and the more familiar sativa and indica strains, autoflowers have risen like a phoenix from the ashes, capturing the hearts and gardens of cultivators worldwide.

These green gems are known for their ability to flower under almost any light schedule, a trait inherited from their hardy Cannabis ruderalis parent, who thrived in the harsh, unpredictable conditions of the Siberian tundra.


Characteristics Of Autoflowering Plant

Auto cannabis are like the chameleons of the cannabis world, adapting and thriving in various environments. They’re a delightful bunch, with unique characteristics that make them stand out in a sea of green.

When we compare auto vs photoperiod plants, autos possess unique traits, including a shorter growth cycle, the ability to flower under any lights cycle, and smaller stature.

Firstly, these compact, pint-sized warriors only need little space to strut their stuff. Their small stature, often half the size of their photoperiod counterparts, makes them perfect for cramped quarters or stealthy operations.

Secondly, autos have a need for speed. They race through their life like a cheetah on roller skates, reaching maturity in as little as 8 to 12 weeks. No more waiting around, twiddling your thumbs as you watch photoperiod take their sweet time to bloom.

Finally, the autos don’t rely on changes in the light to trigger their flowering stage. Instead, they march to the beat of their drum, blooming based on age rather than light exposure. This characteristic is what prompts us to ask the question, “Do autos require darkness?”

Do Autoflowers Need Darkness to Grow and Flower?

Do Autoflowers Need Darkness to Grow and Flower

Ah, the age-old question: to darken or not to darken?

That is the question.

All plants, including our precious autos, partake in a delicate dance between light and darkness.

But what role does darkness play in their growth and blooming?

Let’s embark on a journey to uncover the truth about the necessity of darkness in the plant life.

The Role Of Darkness In Plant Life Cycle

The Role Of Darkness In Plant Life Cycle

The plant life period is like an elegant waltz between the forces of light and darkness, each playing a crucial role in the growth and development of our leafy friends.

To better understand the necessity of darkness for autos, let’s explore the significance of photosynthesis and respiration in plant growth and the function of light and darkness period in regulating their development.

Importance Of Photosynthesis And Respiration In Plant Growth

Importance Of Photosynthesis And Respiration In Plant Growth

Photosynthesis and respiration are the Romeo and Juliet of the plant world – star-crossed processes that fuel growth and development.

Photosynthesis, the process by which plants convert sunlight into food, occurs during light hours, powering our green darlings with the energy they need to flourish.

Respiration, however, is the dark knight of the plant world. It’s a process that takes place 24/7, but its impact is especially felt during the dark hours.

During respiration, plants break down the food produced by photosynthesis to release the energy they need to grow, develop, and repair themselves.

Role Of Light And Dark In Regulating Plant Growth And Development

Role Of Light And Dark Periods In Regulating Plant Growth And Development

As we’ve seen, light and darkness periods play different roles in the lives of plants.

While light fuels the photosynthetic engine, darkness offers a respite from the sun’s relentless rays, allowing plants to rest, repair, and grow.

But what about our star of the show, the auto cannabis?

Does it also need periods of dark to grow and bloom?

Well, the answer is nuanced.

While autos can grow and bloom under constant light, many experienced growers argue that a few hours of darkness benefit these plants, allowing them to recharge and maximize their potential.

Impact Of Light and Dark Cycles

The light for auto cannabis can significantly impact their growth, yield, and quality. Generally, autoflowering cannabis strains prefer a light of 18-24 h of light per day, with the remaining hours in complete darkness.

Here are some ways in which the light can affect auto plants:

  1. Growth: Providing a consistent and appropriate light is crucial for the growth of auto. If the light is too short, the plants may not get enough light to grow properly, and if it is too long, they may not get enough rest.
  2. Yield: Providing a sufficient amount of light for a full 18-24 hour light can lead to highest yielding. However, too much can cause the plants to become stressed and produce lower yields.
  3. Quality: The quality of auto plants can also be affected by the light. Providing a consistent light can help produce consistent buds with higher levels of THC and other cannabinoids. Inconsistent lights can result in lower-quality buds with less potency.

During the dark cycle, plants use the energy produced during the light to repair and grow. Darkness is also necessary for the production of certain hormones, which can help regulate plant growth and development.

Explore our comprehensive guide on maximizing autoflower harvest yields here.

Evidence And Research On The Role Of Complete Darkness In Auto Growth And Blooming

Evidence And Research On The Role Of Complete Darkness In Auto Growth And Blooming

Like brave explorers charting uncharted territories, scientists have ventured into the realm of darkness, searching for answers to the auto enigma.

Some studies have shown that a period of dark, even as little as a few hours, can benefit auto cannabis, promoting robust growth and improved yields.

Studies On The Impact Of Light Cycle And Dark Cycles On Auto Growth And Development

Studies On The Impact Of Light Cycle And Dark Cycles On Auto Growth And Development

The research on lights and auto growth is like a roller coaster ride, with twists and turns that leave us both exhilarated and confused.

Some studies suggest that a cycle of 18 hours of light and 6 hours of darkness is optimal for growing autos, while others claim that a 20/4 or even a 24/0 cycle can produce impressive results.

However, the consensus among experienced growers seems to be that a little bit of darkness can go a long way in ensuring the healthy growth and development of auto cannabis.

Light And Dark Periods

Best For Autoflowers Growing Practices Light Cycle And Dark Periods

For most auto cultivators, the sweet spot lies in an 18/6 or 20/4 light cycle, providing our leafy friends with ample sunlight to fuel their growth while giving them a brief respite in the form of darkness to rest and recharge.

How Much Light is Best for Autoflowers

While the research is still inconclusive, most growers have found success with 18 to 20 per day.

That provides a good balance between fueling photosynthesis and allowing the plants to rest and respire during the darkness period.

Do Autoflowers Require 12 Hours of Light?

Do Autoflowers Require 12 hours of light

Autos will grow, and bloom under a 12-hour cycle, but their growth and yields may not reach the same heights as those grown under longer cycles.

Remember, autos are like sun-worshipping party animals, basking in the glow of extended daylight.

12/12 VS 18/6

While both light schedules can produce successful auto harvests, the 18/6 schedule seems to have a slight edge, providing plants with more energy for growth while still allowing them to rest and recharge during the 6-hour darkness period.

24/0 Grow Lights For Autoflowers

24 0 Grow Lights For Autoflowers

Some daring cultivators have ventured into the realm of 24 hours of light for autos, leaving no stone unturned in their quest for the perfect light schedule.

While auto can grow and bloom under constant light, it’s essential to consider the potential drawbacks of this approach.

Plants may become stressed without any periods of darkness, leading to stunted growth and diminished yields.

Changing Light Cycle for Autoflowering Plants and How it Impacts Harvest

Changing Light Cycle for Autoflowering Plants and How it Impacts Harvest

A change in the light for auto plants can be as thrilling and unpredictable as a plot twist in a gripping novel.

Adjusting the cycle can impact plant growth, blooming, and harvest, so it’s essential to approach this decision with caution and care.

When making changes, it’s best to do so gradually, allowing the plants to acclimate to their new schedule and minimizing the risk of stress.

Grow Journal: Grow An Autoflower Strain with 12/12 Cannabis Light Cycle

Grow Journal Grow An Autoflower Strain with 1212 Cannabis Light Cycle

A grow journal is an excellent way to track the progress of your cannabis throughout their lifecycle.

If you are growing an auto strain, you may wonder about the benefits of using a 12/12 cycle. 

Here is a brief overview of what you can expect when growing an auto strain with a 12/12 light cycle:

When auto plants are 3 week old they should be well-established, and you can start to consider switching to a 12/12 cycle.

This cycle mimics the natural cycle that cannabis experience in the fall, which triggers the blooming stage. In week 1 auto blooming stage, you should begin to see the first signs of flowers forming.

By the time your auto strain reaches 6 week old, it should be well into its blooming stage. One of the advantages of growing an auto strain is that the entire lifecycle is much shorter than that of a photoperiod strain.

Using a grow journal with time lapse photography is an effective way to track the progress of an auto strain grown with a 12/12 cannabis cycle and can provide valuable insights into the growth and development of the plants.

What is Best Light Cycle for Autoflowers and Right Light Spectrum In Seedling Stage

The seedling stage – a time of innocence, vulnerability, and potential.

During this critical period, it’s essential to provide our auto seedlings with the best possible grow room conditions, including the proper light cycle and spectrum.

Most growers recommend a light cycle of 18/6 or 20/4 during the seedling stage, combined with rich blue light, to promote strong, healthy vegetative growth.

Best Light Schedule for Autoflowers Vegetative Growth Cycle

Best Light Schedule for Autoflowers Vegetative Growth Cycle

As our autos transition into the vegetative growth cycle, it’s essential to maintain a consistent schedule to support their continued development and plants grow.

A light cycle of 18/6 or 20/4 is recommended, providing ample energy for growth while still allowing for a brief period of darkness to rest and recharge.

Red Light During Flowering

As our autos enter the blooming stage, they crave the red warm embrace of light, which stimulates the production and increases yield potential.

Providing a light spectrum rich in light during the blooming stage will encourage our plants to produce a bountiful auto harvest.

Perfect Auto Light Intensity During Blooming

Perfect Auto Light Intensity During Blooming

When it comes to intensity during the flowering stage, balance is vital.

Too little light can result in sparse, underdeveloped flowers, while too much can lead to stress and damage.

Aim for “just right” intensity to keep your autos happy and healthy during this critical phase.

Best Nutrients Mix For Autoflower Cannabis Seed

Best Nutrients Mix For Autoflower Cannabis Seed

For autos, a nutrient mix containing nitrogen, phosphorus, potassium, and essential micronutrients is vital in supporting healthy growth, blooming, and yields.

Be mindful not to overdo it; too much of a good thing can lead to nutrient burn, stunted auto and other issues.

Growing Autoflowers Outdoors Without Direct Sunlight

Growing Autoflowers Outdoors Without Direct Sunlight

Picture a scenario where our autos find themselves basking in the great outdoors but lacking direct sunlight – like a sunbather on a cloudy day.

Fear not, for all hope is not lost! With the right approach, autos can still thrive in these conditions.

Provide them with ample light exposure and carefully manage shade to strike the perfect balance, ensuring they receive enough energy to grow and bloom without becoming sun-starved or overheating.


Do autos require darkness to grow?

Yes, autos do need darkness to grow. The dark cycle is essential for their growth and development, as it allows them to repair and grow during the night.

What are the perfect light schedules for autoflower cannabis?

The perfect schedule for autoflowering cannabis is a cycle of 18-24 with the remaining hours in complete darkness.

How long should I keep my plants in the dark?

It is recommended to keep your plants in the dark for 6-12 hours per day during the flowering stage.

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