Growing Auto-flowering Cannabis

auto flowering

Growing Auto-flowering Cannabis

Today, auto-flowering cannabis is on the rise.

Reduced plant size, ease of growing and the rapid speed of growth are all factors which are leading more and more growers to choose this type of seed for their operation over regular varieties.

Many auto-flowers will be prime for harvest after just ten weeks.

The original Dwarf varieties are short and stealthy while still offering decent yields. At the opposite end of the spectrum, super-autos require 100 days to hit maturity. They can grow over 6 feet tall.

With auto-flowering seeds, a novice grower can enjoy bountiful harvests quickly and easily. There is no need to adjust light cycles or to remove male plants – most of these strains (but not all) are feminized.

Many medicinal users of cannabis do not have the time, inclination or expertise to undertake a complicated grow. Perhaps, too, they have limited space.

This is where auto-flowering seeds come into their own.


What are Auto-flowering Plants?

 Regular cannabis shifts from vegetative growth to the flowering stage due to changes in light. These strains are known as photoperiod dependent.

With auto-flowering seeds, as the name suggests, this process is automatic.

Even with 24 hours of light, auto-flowering seeds will happily enter the flowering stage. By contrast, photoperiod plants need 12 hours of darkness to induce flowering.

Short History of Auto-flowering Cannabis

 A strain of hemp called Ruderalis was identified growing wild in Russia back in the 1940s.

Auto-flowering plants today are the descendants of this strain.

Ruderalis plants do not wait for a signal but simply start flowering after 3 or 4 weeks. This shortened lifespan meant that Ruderalis plants were able to flourish and survive in Russia where the summers are short and the winters incredibly long.

Most types of hemp which grow wild, though, contain very little THC. An unknown breeder appreciated the auto-flowering capability of Ruderalis and though that this, combined with the short growing period required, would be potentially useful for hobbyist growers.

To overcome the low THC count, this breeder started to intermingle the strain with famous varieties of photoperiod cannabis. This way, the benefits would remain intact while the bud potency would increase.

After many generations of close and careful breeding, the potency of most auto-flowerers today is indistinguishable from that of photoperiod plants.

Features of auto-flowering plants 

  • Suitable for growing anywhere, indoors or outdoors
  • Usually 30-60cm tall meaning growing in confined spaces or stealth growing are both easy
  • Automatically starts flowering after 3 weeks
  • Seed to harvest around 10 weeks in general 


  • Very short life span meaning more and quicker harvests
  • Multiple harvests every season
  • No need to have separate vegetative and flowering environments
  • Suitable for all climates if growing outdoors
  • Stealth growing possible due to size
  • Simple production of seeds. One plant can yield 100 seeds 


  • Poor reputation for quality with older auto-flowerers
  • Often lower yield than photoperiod strains

Auto-flowering vs Photoperiod Strains 

Time to harvest 

Auto-flowerers do differ but, as a rule, they are ready for harvest within 2-3 months after sprouting. Stems and leaves – vegetative growth – occur for the first 3 weeks then they skip straight to bud.

They continue to grow, both out and up, until just weeks before harvest time. All the energy is then transferred into fattening buds. These buds can gain lots of weight in the lead-up to harvest.

Photoperiod cannabis takes longer, anywhere from 3-4 months after seeds sprout. Grow style and strain can affect this timescale.

They need more time, too, at the vegetative stage.


With autos, each plant tends to yield around 4 ounces. This is impacted by many factors. Poor genetics or weak lighting can reduce this significantly so invest in some great LED lights and maximize your crop.

It should be noted that while these yields are not enormous, the additional number of potential harvests should be considered.

The variation in yields with photoperiod plants is greater. More control is possible over the shape and size of the plant and this alters the yield.

When growing photoperiod cannabis indoors, set-up is absolutely key to make the most of your plants in terms of yield.



 Auto-flowering buds are now no less potent than regular strains. Forget about their reputation and focus on the advances made which has boosted THC up into the 20% range.

Autos have more CBD than photoperiod plants. This cannabinoid is documented for its medicinal properties and can help with anxiety.

If you compare like-for-like, the same strain of auto and photoperiod are roughly the same when it comes to potency. 



As mentioned, autos usually remain short in stature. The short lifespan means large plants are difficult to achieve. They only grow in size for a maximum of 2 months before bud fattening takes all their energy.

4 feet is normally the maximum height.

It’s easiest to say that the sky is the limit with regular photoperiod strains. 

Ease of growing 

Overall, autos are probably the easiest option but there is one major consideration…

If you experience problems from the beginning then the plant will still skip straight to flowering without giving you chance to take action. If you find that your plants are stunted or in any way sick, it will be almost impossible to nurse them back to health.

To look on the bright side, experiencing such problems will teach you a lot and it will soon be time to harvest and start again.

You really need to think about what is best for you and your skill level when it comes to choosing which type to grow. There is less room for maneuver with autos but, if you are confident, they will be a breeze to grow.


We have come a very long way with auto-flowering strains since the days of the first Lowryder plants.

If you have your LED lights and set-up in place then think about some of the above pointers and decide whether it might be time to try giving autos a go.

One Response

  1. Robert Murphy November 13, 2016 Reply

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