Autoflowering vs Photoperiod Cannabis Plants

Autoflowering vs Photoperiod Cannabis Plants

August 01, 2021

When browsing or buying Cannabis seeds you’ll come across the 2 different flowering types: Photoperiod and Autoflowering. It’s essential that you understand the difference between the two before you start growing your own plants, as both have different requirements.

Main Differences

Photoperiod plants are the traditional type of Cannabis plant. They will start to flower and produce buds when their light schedule changes, this happens naturally at the end of Summer when the days become shorter. Indoor growers induce flowering themselves by reducing the amount of light exposure their plants are getting, for example switching from a 16/8 to a 12/12 schedule.

Autoflowering Cannabis plants will start flowering automatically (hence their name) regardless of their light schedule. They were created by cross breeding a regular Cannabis plant with a Ruderalis strain (a hardy Cannabis strain that has adapted to live in harsh conditions.)

Grow Time

Autoflowers grow and fruit faster than their photoperiodic counterparts, the average grow from seed to harvest will take around 2-3 months.

Photoperiods can sometimes take over 5 months to grow and the duration of their vegetative and flowering phases will be determined both by the plant’s genetics and the grower’s personal opinion, as some may choose to keep their plants in the vegetative or flowering phase for longer than others.

Plant Size & Yield

Since autoflowering plants have a limited timeframe in which they can grow, they tend to be smaller than photoperiods, which makes them perfect for indoor growers who don’t have much grow space. Of course the downside to a smaller plant is a smaller yield, though some “super auto” strains have also been bred that can take over 100 days to grow and produce higher yields. Photoperiods have a longer lifespan so they have more time to reach their full potential, this usually results in a much bigger plant if given the right growing conditions.

Another factor to keep in mind that will influence plant size is the size of the pot it’s planted in, if confined to a small pot where the roots don’t have enough space to grow and spread out, your plant’s growth will definitely be stunted. A 12 litre (3 gallon) pot is recommended for most autoflowering strains, any bigger than that is usually wasted space since the lifespan of an autoflowering plant is so short. For photoperiods usually bigger is better especially if you’re growing outdoors or space isn’t an issue.


Autoflowering varieties require little to no maintenance and can be kept on the same light schedule for the whole duration of the grow. You’ll still need to water your plants regularly, and monitor humidity & temperature levels if growing indoors. Depending on the strain and grow medium your plants may benefit from additional feeding, but beware, it’s much harder to recover from overfeeding an autoflower due to it’s limited & short lifespan, so less is more.

Photoperiods definitely require more maintenance and benefit more from advanced techniques like stress training and topping. They usually require more feeding due to the fact that the nutrients in their grow medium get depleted quicker because of their larger size.


Initially when autoflowers started being produced commercially in the early 2000’s, they were pretty underdeveloped and their THC levels were nowhere near as potent as photoperiod strains. These days Cannabis breeders have come a long way and most autoflowering strains are just as potent as their photoperiodic cousins, sometimes even more.

Which Should I Choose?

Photoperiods are great if you have the space, knowledge and patience to care for them properly, and the harvest potential definitely cannot be matched by most autoflowers, however, if you’re a beginner and just want to grow some Cannabis without worrying too much about light schedules and maintenance, then you should definitely go for autoflowers.

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