Frequent doubts about growing Autoflowering Cannabis

Principle characteristics of Automatic plants

Autoflowering or Automatic cannabis seeds are characterised by being varieties that flower all by themselves, or in other words, they are not photo-dependent, unlike photo-sensitive feminised cannabis seeds they do not depend on the cycle of light and darkness to trigger bloom.

Once the seed germinates, it goes through its vegetative growth period of about 15-21 days, after which in then begins flowering, regardless of the hours of light it receives.

This is the feature that makes autos so popular with many growers, as they can deliver a harvest just 60-80 days after germination, much faster than any traditional genetics.

Cheesy Auto CBD in full bloom
Cheesy Auto CBD in full bloom

Despite this, many growers have never tried autoflowering seeds, believing that they are more difficult to grow or require special care, when in reality, all we need to do is take some basic concepts into account when working with them.

For this reason, in this post we’re going to address some of the most frequent questions about autos, and at the same time, we’ll expose the pros and cons of growing autoflowering cannabis.

What are the benefits of growing Autos?

The main advantage of automatic genetics is, undoubtedly, the rapid life cycle of between 65 and 90 days, depending on its genetics and its sativa influence, which allows us to enjoy our cannabis harvest in record time.

This is perfect for those growers who don’t want to invest a lot of time cultivating, allowing them to get several harvests during the outdoor season, by staggering them. In this way, they can achieve abundant yields of flowers by making the most of small spaces, and have something to smoke during the summer, before the feminised or regular plants complete their development outdoors.

Sleepy Yoda Auto full of buds
Sleepy Yoda Auto full of buds

Another advantage is their height, rarely exceeding 1-1.5m tall, which makes them perfect for terrace or balcony growing, making sure that we won’t bother the neighbours and that the plants won’t be seen, meaning we can sow them almost anywhere without any problems.

Similarly, growers who prefer to cultivate indoors can be confident that they won’t have any height problems, since the plants limit their own vertical growth naturally or alternatively, we can limit their development by choosing a smaller pot to grow them in.

Autoflowering plants do not require a change of photoperiod to trigger flowering, instead they will start to create buds by themselves after 15-21 days of vegetative growth, which means that the more hours of light we give them, the faster they will grow and consequently more flowers will be produced, with the ideal photoperiod being 20h/4h.

This also means that light pollution does not affect them, so there is no way to interrupt their flowering once it has started, which guarantees we will get satisfactory results in the time promised, without revegetation taking place.

As for the nutrients, if we use a specialist soil for cannabis with enough nutrition for 3 weeks, we’ll only need to apply flowering fertilisers, with no need for growth nutrients, this is because their nitrogen needs are very low compared to feminised genetics.

Cheesy Auto, aromas of cheese and forest fruits
Cheesy Auto, aromas of cheese and forest fruits

What are the disadvantages of growing Autos?

Regarding the disadvantages, there are very few in comparison to the advantages, we can point to their size and their short vegetative time, meaning we always obtain small plants, which in turn means that they won’t give us more than 150-200g per plant, both in outdoor cannabis gardens as well as indoor grow tents.

This point is quite subjective, as while autos may disappoint lovers of huge, bud-laden plants, they are ideal for those who want to grow discretely, and harvest a good ratio of buds to plant size.

Another difference is that autoflowering plants offer, on average, THC levels between 18% and 20%, which are similar to those of most feminised genetics, however, non-auto varieties are capable of offering a higher concentration of this cannabinoid, reaching as high 25% -28% in some cases, while with autos, this does not happen.

Another point that we must take into account is that we cannot take vegetative cuttings from autoflowering plants, meaning we can’t keep a mother plant, since any clones will behave like the seed plant, starting flowering when they reach maturity, after a very short time.

Finally, some growers believe that autos aren’t suitable for indoor cultivation, since they need a large pot that’s taller than it is wide (between 15 and 20 litres) to offer their full potential, occupying a lot of closet space and only allowing us to grow a few plants every time, which doesn’t take advantage of all the light energy used.

Lemon Auto CBD, citric and therapeutic
Lemon Auto CBD, citric and therapeutic

But this is just an opinion, as, if we want, we can also choose to grow more plants in smaller pots, with a photoperiod of 20h/4h to achieve the maximum possible yields and resin production, taking full advantage of their capabilities, which we are unable to do in outdoor grows.

Why is my autoflowering plant so small?

With all that has been said so far, now it’s time to address this question, one that we’ve all made at some point when cultivating Autoflowering genetics. My plants haven’t grown, why is that?

Well, in short, we can point either to environmental causes, or to stress, or to the size of the pot and the amount of substrate.

Basically, autoflowering plants have a very short growth period, as we’ve already mentioned, and they need to take full advantage of this brief time to grow as much as possible.

In addition, the more space available to the plant’s main root, the taller it will consequently grow, which is why these plants show their maximum potential if we sow them in open ground, where they are free of the restrictions imposed by the size of the pot.

Cheesy Auto CBD, sweet and medicinal
Cheesy Auto CBD, sweet and medicinal

This means that, if during this stage the plant suffers any type of setback, it will halt its growth due to stress, taking a week to recover and resume its development and thus wasting this precious time, reaching a much lower final height than expected.

If we sow the plant in too small a pot, or if it receives very few hours of sunlight, or bad weather and cold, or if we use a very compact soil that hinders root development, or we don’t provide enough fertiliser, or it suffers cannabis pests or fungal diseases, the plant will slow its development, remaining very small.

The ideal method is to sow it in a deep pot or in open ground, using an aerated, balanced and quality substrate, during spring/summer, when there is no cold or frost, with sufficient hours of light (ideally 16h- 20h), watering it with care, avoiding both deficiencies and excesses, to achieve optimal development.

Can I prune my automatic plant?

Main bud of Cheesy Auto CBD
Main bud of Cheesy Auto CBD

As we’ve already mentioned, it’s not recommended to take cannabis clones from automatic plants because they quickly begin to bloom, and it’s not advisable to prune them either, and certainly not in the short growth phase, since if we cut their branches, we will provoke stress and slow down their development.

In other words, if we prune the plant, the wound we inflict will cause changes to its metabolism, altering its normal functions and forcing it to stop development until it has healed, which means that the growth halts, and the final height of the plant is reduced. This takes valuable resources away from the plant and prevents it from showing its full potential, squandering its capabilities.

Which plant pot and fertilisers do I use with Autoflowers?

If we are going to plant them on a patio, a balcony or indoors, we must use a pot, either a rigid one or a fabric one of the Smart Pot type. The volume that we choose will determine the final size of the plants, becoming smaller as we reduce the volume of the containers.

If we want the plants to offer their full potential, we should use an 18L conical pot, with deeper than it its wide, which allows maximum development to the main taproot. But if we want to control its height for a discrete grow, we can opt for pots of 10-12L maximum capacity.

As far as the choice of fertilisers goes, it’s a personal preference, and we can use the brand we like the most, either organic, bio-mineral or pure mineral, as long as we always remember that they don’t need high concentrations of nitrogen due to their short vegetative growth period.

Fraggle Skunk Auto, highly resinous
Fraggle Skunk Auto, highly resinous

If we provide too much Nitrogen, we run the risk of the buds not compacting well, having an airy structure and being too green, sacrificing flavour considerably.

Ideally we will use an All Mix soil, which has enough fertiliser for the first three weeks of plant development, accompanied by a root stimulator. Then we would use a flowering fertiliser with its respective stimulators and enhancers to avoid any problems.

Can I cultivate Autos as SCROG or SOG?

Autoflowering cannabis varieties are not suitable for this method of cultivation. This is because plants grown in SCROG require several weeks of vegetative growth to allow them to develop enough branches and thus fill the growing space, something that can not be done with automatics as their growth period is limited to 2-3 weeks.

To cultivate cannabis using the SCROG method, non-autoflowering varieties with at least 50% Sativa genetics are recommended. For this type of crop, we need to give a longer growth period than for SOG cultivation, at least 20 days.

The recommended varieties for the SCROG technique are Easy Haze, Amnesika 2.0, Fruity Jack and our regular variety Jamaican Blueberry BX.

When it comes to growing Autoflowers in SOG, it can be done by using small pots (5-7L), filling the grow space with them so that the plants only develop a central tip with hardly any side-branching, but we would achieve the same result as using photo-sensitive feminised plants, with no real advantage.

Happy growing!

Comments in “Frequent doubts about growing Autoflowering Cannabis” (2)


Ryan 2020-05-10
Great and insightful share, thank you from California. First time grower starting with auto flowers. I would be very interested in learning more about not being able to take vegetative cuttings.


louis (TONY) maloney 2019-12-20
I'm a little bit past my teen years, & thankyou so much for your knowledge of Autoflowering. If my wife of (30) years was still alive, she would know what to do & NOT do. Anyway thanks again. The beginning.

Philosopher seeds Staff

laia 2020-01-17
Pleased to help, but so sorry about your wife. :( All our best vibes!

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