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autoflowering cannabis seeds light cycle

• Easy, doesn’t require a timer
• May provide the best yields

MH bulbs emit a more bluish light optimal for the growing stage of cannabis. Once a plant goes into flowering, MH bulbs are switched out for HPS, which give off a more orange/reddish light spectrum ideal for promoting bud growth.


60–70 days. Because they grow and finish so quickly, this means you can achieve multiple outdoor harvest per year, or even per season! If you time your grow op right, you can harvest cannabis pretty much all year.

• Stresses equipment more
• Largely under-practiced

• Potentially less stress on your plant
• Theory supports greater production potential
• Can make for a more stable environment (temperature, etc.)

This means that the best light schedule for autoflowers is either 24/0, 20/4, or 18/6 so there are multiple options and the best one will depend on your growing environment and setup.

Unlike photoperiods that need at least 12hrs of darkness to trigger flowering, autoflowers automatically enter the flowering cycle when they’re mature enough. They start producing buds based on age thus they don’t depend on darkness to start the flowering cycle.

1. What is the best light cycle for autoflowers?

There are growers who believe autoflowering plants need a dark period and won’t be as healthy if they get a 24/0 light schedule. There’s no real evidence of that but there may be exceptions. Also have in mind that a 24/0 will lower humidity , increase temperature , and increase the light bill .

You can leave your lights at night and have them turn off during the 6 hottest hours of the day. By using this schedule you’ll be using around 25% less electricity, which adds up to be a good economy at the end of every harvest.

For example, during the vegetative stage, your plants will need a blue spectrum that ranges from around 400 to 550nm whereas during the flowering stage your plants will need a red spectrum, with wavelengths that range from 550-700nm.

However, their yields aren’t as spectacular as those obtained from photoperiod giants, but, the trade-off for brevity makes the decision worthwhile for most growers.

Follow the fail-safe week-by-week grow guide below for a quick and easy route to harvest time. We cover all of the parameters and variables you need to consider—at the correct times—to ensure your plants remain healthy, vigorous, and productive.


8 weeks, with subsequent weekly harvests when growing fast strains.


As the name suggests, autoflowering strains don’t require a change in the light cycle to enter the flowering stage. Many growers choose to keep their autoflowers on a light schedule of 18 hours on and 6 hours off during the entire growing cycle. Other cultivators choose to keep their lights on around the clock in hopes of maximising photosynthesis and growth rate, however, this can get quite expensive.