For indoor autoflower cultivation, the commonly recommended light cycle is 20 hours of light and 4 hours of darkness. This cycle is often considered optimal for promoting vigorous growth and maximizing yield throughout the plant's life cycle.
Understanding Autoflower Light Requirements
Autoflowering cannabis plants differ significantly from photoperiod strains because they transition from the vegetative phase to the flowering phase based on age, not changes in the light cycle. This unique characteristic means they do not require a specific 12 hours of darkness to initiate flowering, unlike photoperiod varieties.
Because autoflowers are not dependent on darkness to flower and have a relatively short life cycle (typically 8-10 weeks from seed to harvest), growers aim to provide them with as much light as possible without causing stress. More light generally translates to more energy for growth and bud development.
Based on common practice and grower experience, the best light cycle for autoflowers is often considered to be 20 hours of light and 4 hours of darkness (20/4). This provides extensive hours of light for photosynthesis while still allowing a short period of darkness for essential plant processes like respiration and nutrient transport.
Why 20/4?
Choosing a 20/4 light schedule for autoflowers indoors offers several benefits:
- Maximizes Growth: Providing 20 hours of light daily gives plants ample time to photosynthesize and build energy, leading to faster vegetative growth and larger flowers.
- Consistent Development: Since flowering isn't triggered by light changes, a consistent long light cycle supports uninterrupted development from seed to harvest.
- Efficient Use of Space: The faster life cycle supported by optimal light usage allows for multiple harvests per year in the same space.
While 24 hours of continuous light is sometimes used, the consensus often leans towards including a short dark period (4 hours) as it is believed to benefit overall plant health and development, although the specific reasons are debated among growers and researchers. Conversely, shorter light cycles like 18/6 are also used, but 20/4 is frequently cited as providing the best balance of growth potential and plant rest.
Practical Considerations
Implementing a 20/4 light schedule requires reliable equipment:
- Grow Lights: High-quality LED, HPS, or CMH lights are suitable. Ensure the light intensity (PPFD) is appropriate for the growth stage.
- Timers: Digital or mechanical timers are essential to automate the 20 hours on / 4 hours off cycle accurately every day.
- Environment Control: With 20 hours of lights on, managing temperature and humidity in the grow space becomes crucial.
In summary, to answer "How much light do autoflowers need indoors?", a cycle of 20 hours of light and 4 hours of darkness is widely regarded as the most effective schedule to optimize their unique growth characteristics.
