By / September 3, 2019

How do you grow auto-flowering cannabis plants?

There are always trends and new technologies within the cannabis industry that are not accepted by the plant-growing community. This is usually the case, at least at the beginning, of each innovation. This happened with feminized cannabis and also with LED lamps for indoor growing.

The situation is very similar for self-flowering cannabis varieties, the so-called automatic or auto-flowering strains. These hybrids have the unique ability to automatically enter flowering regardless of the daily duration of light.

What are auto-flowering plants?

With these auto-flowering cannabis strains and ruderal hemp, it is not necessary to trigger the flowering impulse by shortening the photoperiod to 12 hours of light and 12 hours of darkness.

But what is ruderal hemp and why does it bloom by itself, independent of the light exposure? The rudder hemp is Cannabis Ruderalis and it is wild from the Caucasus to China.

“The wild ruderal hemp grows to only 30 to 60 cm in height, has almost no branches and quite small leaves. The inflorescence is not particularly luxuriant and occurs only at the end of the stem. The seed coat has a fleshy base,” continues Rätsch.

A smaller but tough breed

Due to the rather long and usually quite cool days in this area, the flowering of this cannabis species does not depend on the light. Reaching the appropriate vegetative stage is more crucial so that the plants have the chance to reproduce in the wild. The rather harsh climate in the Eurasian home area of Cannabis ruderalis (where even snow can sometimes cover the plants) has made the plants grow relatively compact and small.

If Indica plants are small compared to Sativas, ruderal hemp is the dwarf of the family. The flowering behavior and the relative compactness, which are peculiar to cannabis, are both characteristics advantageous to growers. Therefore, breeders have started to introduce these characteristics of ruderal hemp by crossing them into the common Sativa and Indica strains.

The resulting strains bred have a proportion of between 10 and 35 percent Ruderalis genetics. Christian Rätsch says, “Very popular are crosses of Cannabis indica and Cannabis ruderalis, because they are very small and at the same time highly potent. Crosses with Cannabis Ruderalis suit outdoor cultivation. They ‘bloom’ early regardless of the length of the days.”

He continues: “And in fact, over time, plants have emerged that are easy to grow, sometimes enormously potent and barely noticeable, and can ripen early.”

Advantages of auto-flowering cannabis at a glance

Cultivation of cannabis is still forbidden in most areas. It can be a great advantage to work as a guerilla grower with “automatic” plants. But even if you don’t have to hide from the eyes of the law, here are some of the advantages of these strains:

  • Sowing of the seeds to the harvesting of the weed usually only takes about ten weeks.
  • The plants start flowering after two to five weeks regardless of the photoperiod.
  • Due to rapid growth and flowering, several harvests per season are possible
  • Automatic cannabis is mostly small (many varieties only up to about 70 cm) and therefore only slightly conspicuous.
  • Auto-flowering plants usually do not produce such a strong odor as normal strains.
  • Auto-flowering cannabis is feminized, so it does not produce male plants.

Do these plants also have disadvantages?

Auto-flowering strains have noticeably improved in quality these days, much better than they were just a few years ago. Also, almost all classic and proven strains are now also available in auto-flowering versions.

The only real disadvantage of auto-flowering plants is the small quantity that can be expected per crop and specimen, due to their small size. Average “auto” plants usually weigh between 15 and a maximum of 75 grams of grass. The latter is already quite high in most cases.

Neither cuttings nor mother plants are produced from such varieties. This causes a further possible disadvantage of “automatic” plants. And who knows what the breeders of this world will come up with in the future?

One of the disadvantages of growing auto-flowering plants is the quantity per crop. (Source)

Indoor or outdoor?

Since most strains ripen within 10 or 11 weeks, it is possible to grow several times a year both in the field (in our tubs, of course) and under artificial lighting indoors. They remain slightly smaller inside than outside and grow a little more compactly. Still, the yield should be similar for both settings.

The lighting of the plants

There are recreational growers who simply plant their auto-flowering cannabis in the tub, leave it outdoors, water it from time to time, and perhaps even fertilize it. They can opt to do nothing else until the plants are fully ripe. This works with self-flowering strains.

Some car growers simply give their pupils 18 hours of light a day; the rest is done by Ruderalis genetics. As mentioned above, the photoperiod does not have to be changed to a 12/12 hour cycle to start flowering. Again, auto-flowering plants start to bloom regardless of daily light duration.

Choosing the right variety

It is important to consider how much space is available for the plants and how high they are allowed to grow. There are auto-flowering strains that grow to about 1.5 meters in height, but there are also strains that grow to only 30 to 50 centimeters.

In addition, it must be decided whether the grass should be more indica or sativa branched. Furthermore, whether it should contain more or less THC or CBD. How much time one wants or can invest is also a factor. The expected yield is also important.

Auto cannabis: perfect for patients?

Auto-flowering strains are perfect for cannabis patients who cannot or don’t want to expel so much effort in growing cannabis.

A car plant usually tolerates cooler temperatures or temperature fluctuations. It is not complicated or tricky to care for, and can be harvested in a few weeks. Car plants can also be grown much more easily than balcony plants because do not depend on lighting cycles. This makes these plants suitable candidates for cannabis patients who do not have the time or energy to take care of their planting.

Auto-flowering cannabis is certainly not yet fully developed. For many breeders and enthusiasts, “automatic” plants are certainly a nice change. It gives them easy gardening success sans the usual frustrations that come with growing plants.

First published in Hanf Journal, a third-party contributor translated and adapted the article from the original. In case of discrepancy, the original will prevail.

Although the author made reasonable efforts to provide accurate translations, some parts may be incorrect. assumes no responsibility for errors, omissions or ambiguities in the content provided on this website. Any person or entity relying on the translations does so at their own risk. is not responsible for losses caused by such reliance on the accuracy or reliability of translated information. If you wish to report an error or inaccuracy in the translation, we encourage you to contact us.

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