Useful guide for growing autoflowering plants outdoors and indoors, discover the best techniques for cultivating autoflowering plants.
Autoflowering cannabis is a unique variety of weed that, unlike the other two species indica and sativa, is not photoperiod-dependent. This means that regardless of the increasing or decreasing hours of light, autoflowering indoor and outdoor seeds produce plants that will flower after a growth period of no more than 25-35 days.
The flowering time ranges from 35 to 50 days. In conclusion, by growing autoflowering marijuana, you can have mature plants ready for harvest in as little as 65 days for the fastest varieties, up to a maximum of 80-90 days for XXL autoflowering strains.
Based on sales statistics, there is no doubt that autoflowering seeds have far surpassed the sales of their feminized counterparts.
This is due to their fast growth and compact size, making them easy to cultivate in gardens, balconies, and small indoor spaces. Today, all seed banks offer a catalog of autoflowering strains, including Dinafem, Sweet Seeds, Barney's Farm, Royal Queen Seeds, Sensi Seeds, etc.
If you're interested in learning more about the differences between various cannabis seed types, check out our guide: Differences between feminized, autoflowering, and regular seeds
Growing autoflowering plants: Some Tips
Growing autoflowering plants has become almost a trend among European growers in recent years. Whether due to their ease of cultivation or their small size, the fact remains that almost everyone has tried growing these genetics.
In this article, we aim to highlight the key differences and advantages of growing autoflowering cannabis compared to traditional marijuana plants.
As mentioned earlier, the main difference is their independence from the photoperiod. This characteristic allows for rapid and immediate flowering even during periods of the year with increasing daylight hours (e.g., February-July).
However, autoflowering cannabis plants require a different nutrient regimen than traditional plants. For example, since the vegetative phase is very short, nitrogen fertilizers should be used sparingly and in moderation, as after just 25-30 days, the plant's nutritional needs shift towards flowering.
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Additionally, due to their rapid growth and rooting phase, pots larger than 15-18 liters are not recommended, as autoflowering marijuana does not have enough time to fully expand its roots within the soil block.
Another important tip is to minimize transplants. Autoflowering cannabis plants do not tolerate frequent transplant stress well.
How to Grow Autoflowering Plants Outdoors
How to grow autoflowering plants outdoors? Let's start by describing the growth and flowering cycle of these cannabis seeds: In our latitudes, it is possible to grow autoflowering seeds outdoors starting in April, weather permitting, while the last autoflowering seeds of the season can be germinated around mid-September.
The maturation time, as mentioned above, is determined not by light hours but by the genetics of the autoflowering marijuana being grown. Typically, indica-dominant strains, such as Cream Caramel Auto, are the fastest, ready for harvest just 60-65 days after germination.
Meanwhile, more sativa-dominant varieties, like Autoflowering Amnesia Haze and XXL auto versions, can take 75-90 days to be harvested. The optimal period for outdoor autoflowering cultivation is closely linked to seasonal trends.
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For instance, the same plant grown from April to early June will never yield as much as one germinated in mid-to-late May and harvested between late July and early August. This is because these two periods provide very different climatic conditions, from daylight hours to temperature.
Our opinion on autoflowering marijuana cultivation is that it performs much better outdoors. Autoflowering plants thrive in natural sunlight much more than under artificial lighting.
With autoflowering cannabis outdoors, it is possible to complete up to 3-4 cycles per season in favorable latitudes, such as southern Spain, where the warm season lasts much longer. When growing autoflowers outdoors, it’s best to use medium-sized pots of at least 12-15 liters—something that is not recommended for indoor cultivation.
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Growing Autoflowering Indoors: Cultivation Time
Autoflowering indoor growth and flowering time, along with the ideal lighting hours for these genetics: For years, many growers have preferred to cultivate autoflowers indoors, thanks to their excellent organoleptic qualities and moderate yields that autoflowering seed varieties offer.
The maturation time is very similar to outdoor cultivation, but in indoor growing, the flowering period tends to be slightly longer due to the type of artificial lighting used.
To grow autoflowers indoors, the recommended light schedule is 18 or 20 hours per day throughout the plant's entire life cycle, from germination to harvest. For more details on light scheduling, check out our guide: Light hours in cannabis cultivation
The two schools of thought regarding indoor autoflowering light schedules:
The 18-hour light cycle is considered the standard for indoor autoflowering marijuana cultivation, ensuring good yields.
Meanwhile, some growers claim that a 20-hour light cycle maximizes final production, but others argue that after 18-19 hours of light, the plant becomes stressed due to insufficient rest time from its biological activities.
When growing autoflowers indoors, one must consider electricity consumption, which is at least 1/3 higher than that of regular feminized plants. Running 18 or 20 hours of light for 60-70 days is far more expensive than 18 hours for 15-30 days of vegetative growth, as with standard or feminized plants. Choose the best light for autoflowering plants.
Feminized Autoflowering Seeds
Are autoflowering seeds feminized? This is a common question among buyers. Some less experienced growers confuse autoflowering seeds with feminized seeds. In reality, feminized seeds refer to photoperiod-dependent seeds, whereas feminized autoflowering seeds are commonly called just autoflowers. This is because autoflowering seeds are inherently feminized, as regular autoflowering seeds are either nonexistent or extremely rare in the market.
In conclusion, all commercially available autoflowering seeds are feminized and produce only female plants.
Growing Autoflowers in Winter
A frequently asked question is whether it is possible to grow autoflowers in winter. The answer depends on the climate zone you are in. To cultivate any variety of autoflowering marijuana, a mild climate and increased daylight hours during spring or summer are important. However, in certain regions of the world, cannabis autoflowering seeds can be grown and flowered year-round.
Cannabis plants are highly resilient, and if grown in an excessively cold winter, they may enter a state of vegetative dormancy, pausing their growth until temperatures rise again. Therefore, in colder climates with limited daylight hours, outdoor cannabis cultivation should be timed with the appropriate season. Autoflowering marijuana seeds can be germinated from early spring until mid-August. Meanwhile, indoor cannabis cultivation allows for year-round autoflower production.
How Much Does an Autoflowering Plant Yield During Flowering?
How much does a flowering autoflowering cannabis plant produce? This is one of the most frequently asked questions by cannabis seed buyers. The answer is not straightforward, as multiple factors can influence the final yield of an autoflowering plant during flowering.
How much weed do indoor autoflowers produce?
On average, an autoflowering plant, when grown with care, in quality soil and with the correct doses of fertilizers, can yield between 30 to 50 grams of dry product per plant.
Meanwhile, among XXL autoflowers, there are varieties that can produce up to 100-120 grams, such as the famous Magnum by Buddha Seeds or the XXL versions by Dinafem and Sweet Seeds. However, all experienced growers know about the variability in the plants produced by flowering autoflowering marijuana. Therefore, the estimated yield per plant cannot be guaranteed, even when following all cultivation guidelines. If you want to learn more, check out our guide: How to manage cannabis flowering without making mistakes.
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To test autoflowering flowering, several experiments were conducted on cannabis cultivation. Here are the details: 100 plants of the same variety were grown under identical conditions—same soil, lighting schedule, and fertilization. By the end of the cultivation period, significant variation in yields was observed, with some plants producing 45 grams, others 12, and others 20 grams, and so on.
By averaging the total harvest, the yield per autoflowering plant ranged from 20-35 grams. Thus, the biggest challenge of flowering autoflowering cannabis is certainly the variability. To explore this further, check out our guide on Cannabis harvesting and drying
How to Grow Autoflowering Marijuana
How to grow autoflowering marijuana? You can purchase a indoor autoflowering cultivation kit to grow all year round or an outdoor autoflowering cultivation kit to grow externally during the spring/summer season. Since these plants remain compact, using large pots (over 15-16 liters) is unnecessary. Conversely, we do not recommend pots smaller than 7 liters, as they could lead to premature flowering.
Frequent transplants are discouraged, with a maximum of one during the vegetative phase. However, our best advice is to germinate the cannabis seed and place it directly in the final pot.
Choosing quality soil is crucial for cultivating autoflowering varieties. Planting an autoflowering plant in rich, well-aerated soil provides balance, stability, and essential nutrients for the delicate early stages of growth. We recommend using airy substrates such as Biobizz Light Mix, Atami Janeco Light Mix, or Canna Terra Professional.
Water should be given in the right amounts without overwatering, ideally with a pH between 6 and 7. It is well known that autoflowering strains do not tolerate excessive stress or various cultivation techniques. However, the only cultivation method they respond well to is LST (Low-Stress Training). This technique increases the yield of autoflowers. If you’re interested, check out our guide on Low-Stress Training for cannabis.
When watering, make sure to thoroughly soak the soil until water drains from the bottom holes of the pot, then wait for the soil to dry before watering again. Fertilization is also essential, starting with good doses of root stimulators, minimal applications of growth fertilizers, and normal doses of flowering fertilizers and stimulators.