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How To Grow Autoflowering Cannabis Plants

Here's the complete guide with everything you need to know to successfully grow these fast-developing cannabis plants from seed to harvest. Created with Seedsman.

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Fast, easy, and reliable, autoflowering cannabis plants offer a range of benefits over regular photoperiod varieties and are hugely popular among beginner growers and seasoned cultivators alike.

As their name suggests, autoflowering genetics (or “autos”) initiate flowering automatically once they reach maturity, rather than taking their cue to do so from changes in the light cycle.

This makes life a breeze for growers, who are relieved of many of their maintenance duties and can simply watch their plants race from seed to harvest in as little as ten weeks.

Advantages Of Autoflowering Plants

Autoflowering cannabis cultivars were originally created using genetics from an extremely robust wild hemp strain called Ruderalis, which hails from the cold, dark forests of eastern Europe. While this parental plant offers little in the way of flowers or cannabinoids, it does provide certain highly useful adaptations, such as resistance to pests, an indifference to low light and cold, and an extremely fast life cycle.

Crucially, while photoperiod cannabis plants hold off flowering until late in the autumn, when nights are around 12 hours long, Ruderalis flowers automatically once it reaches a certain age. By painstakingly crossing Ruderalis with certain popular photoperiod cultivars, breeders have managed to create autoflowering cannabis that offers the best of both worlds.

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It took a while to perfect the genetics, but many autoflowering cultivars now more or less match photoperiod varieties for cannabinoid content, with some containing upwards of 20 percent THC.

Obviously, the main advantage of autos is that they eliminate the need for growers to control the light cycle, and can therefore be grown indoors or outdoors with the minimum of fuss. Yet the speed at which they reach maturity is another major bonus.

The fact that autos can be harvested in as little as eight to ten weeks is excellent news for anyone living in cold locations with short summers, as it makes it possible to squeeze a full outdoor grow cycle into those few warm months.

People in hotter, sunnier locations, meanwhile, may be able to fit as many as two or three full cycles into each summer.

Photo by Irina / Adobe Stock Photo

Because of their relatively short vegetative stage, autos invariably remain much smaller than photoperiod cultivars and rarely exceed a meter in height.

While this means that they typically produce smaller yields, it also makes them more practical, as they can easily be grown in compact spaces and are therefore more suitable for indoor cultivation at home.

Where To Get Autoflowering Seeds

One of the pioneers in cannabis, Seedsman.com was first to make autoflowering genetics available to the wider market through sales online in 2006. Since then, the company has since evolved and expanded to become one of the leading seedbanks in the world.

With operations in Spain and the UK, Seedsman offers its own premium quality genetics, currently 57 strains with new strains being added, while also maintaining one of the most comprehensive libraries of cannabis seeds including more than 2,000 strains from 65 different brands.

Photo courtesy of Seedsman

Seedsman often has special offers on autoflowering genetics this time of year including their current 3 for 2 promotion on Seedsman as well as other top-selling brands now through the end of June.

Seedsman auto strains of note include the newly launched Alaskan Diesel Auto that produces resinous buds, a sweet diesel taste, and a potent high; Gelat.OG Auto with plenty of THC, a rich dessert-like scent, and earthy notes on the palate; the hugely popular Alaskan Purple, a winner for its generous yields, adaptability, sweet taste, and characteristic purple hues; as well as the recently launched Strawberry Cheesecake Auto that produces dense and resinous buds with good THC levels, and relaxing, yet mentally stimulating effects.

Tips For Growing Autoflowing Cannabis

Speed is one of the distinguishing attributes of autoflowering cultivars, and while this is obviously a highly desirable trait, it also makes plants less able to deal with certain stresses.

Photoperiod plants, which may vegetate for several months, have plenty of time to recover when they experience a shock to the system, but autos don’t have that luxury, which is why cultivators must make sure to avoid stressing their plants.

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It’s therefore advisable to sow your seeds directly into their final growing container, rather than starting them off in a small pot and transplanting them into something bigger later on. Doing so usually sends a plant into transplant shock, which can stunt its development for a period of time.

Given that autoflowering cannabis has such a short growing cycle, such setbacks can negatively affect the final harvest and must therefore be avoided.

Typically, autos do well in pots that can hold ten to 15 liters, as this allows enough space for their roots to develop. Because time is of the essence, plants need to expand their roots as quickly as possible after germination, so it’s best to opt for a light and airy soil that won’t impede growth.

Photo by RYLAND ZWEIFEL / Adobe Stock Photo

Standard potting mixes generally work pretty well for autoflowering cannabis, although they can sometimes be a bit rich. Because autos require less nitrogen and other nutrients than photoperiod cultivars, it’s always a good idea to go for a soil that is only lightly fertilized.

You can also make your own soil by mixing three parts peat moss, three parts compost, one part coco coir or perlite, and one part vermiculite. Be sure to keep an eye on the acidity of your soil too, as autoflowering plants grow best when the pH is between 6.0 and 6.5.

Adding extra nutrients is usually unnecessary when growing autoflowering cannabis, although it may be called for if you start to notice signs of deficiencies during flowering, such as yellow leaves. Similarly, water should only be applied as and when necessary, and not on a fixed schedule.

Overwatering can be fatal for autos, so it’s a good idea to keep an eye on your plant’s soil and only water when you notice it drying out.

Photo by encierro / Adobe Stock Photo

Once your plants are growing nicely, the best approach is to simply leave them alone. With photoperiod cultivars, many growers apply stress techniques like topping, pinching, or trimming, all of which are designed to shock the plant into flowering earlier or increasing cannabinoid production.

With autos, though, such methods can have a detrimental effect on the final harvest and are therefore best avoided. Having said that, some cultivators do choose to apply low-stress training to autoflowering plants, which involves gently bending the stem and tying it down in order to expose more bud sites to the light source.

This brings us neatly onto the topic of light. This might seem a bit redundant given that autoflowering plants don’t depend on the light cycle in order to flower, yet it’s worth bearing in mind that the amount of light they receive can still have a significant impact on their ability to photosynthesize, thereby affecting their final size and yield.

If growing outside, it’s therefore best to plant seeds in late spring or early summer, so that plants can bask in the long summer days while vegetating.

Photo by contentdealer / Adobe Stock Photo

Indoor growers, meanwhile, have more control over the light cycle, and must therefore decide exactly how much illumination to provide. Some people go all out, hitting their plants with 24 hours of light throughout their grow cycle, yet this strategy comes with a hefty energy bill.

Most growers therefore stick to 18 hours of light per day, as this saves on energy while still producing excellent yields.

FAQgrowinghow tolearnseeds
June 03, 2021
Written by Herb
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June 03, 2021
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