What are Fast or fast flowering cannabis strains?

Fast strains represent a significant advance in the genetic developments within the cannabis market of the last few years. These varieties offer all the benefits of photo-dependent feminised genetics but with a shorter flowering time, which is a huge advantage for growers in regions with cold climates and short summers, as well as for those looking to maximise their number of annual harvests. Here we tell you everything you need to know about these strains!

Fast flowering strains, also known as “Fast” or “Early”, are an innovative solution for growers looking to reduce the flowering time without sacrificing the quality of their crops. These varieties combine the genetics of photo-dependent and autoflowering plants, resulting in specimens that require a specific light cycle to flower, but with a shorter flowering period than that of traditional strains.

The development of these genetics started in the early 2010s, when breeders were trying to create automatic versions of photo-dependent strains (i.e., those that flower depending on the photoperiod, or the hours of light and darkness that they’re exposed to). By crossing autoflowering plants with their photo-dependent sisters, it was soon discovered that the new strains were not fully autoflowering, but had a faster flowering cycle. This discovery led to the creation of F1 hybrids, which could complete their flowering cycle in 6 to 7 weeks (1 to 2 weeks earlier than their photo-dependent counterparts).

How do you get fast flowering strains?

In short, Fast cannabis is obtained by mixing photo-dependent and autoflowering varieties. More precisely, by crossing a photo-dependent feminised strain with a feminised autoflowering, which results in a plant that has the autoflowering gene but still depends on the photoperiod.

This happens because the photo-dependent feature is dominant over the autoflowering trait, which actually is recessive. But, even if the autoflowering genetics isn’t dominant, its presence leads to quicker flowering times. The result is a strain that can be harvested earlier whilst still providing high yields and the potency levels of a traditional photo-dependent plant.

Fast flowering strains vs autoflowering varieties

Given that the term “fast version” refers to plants that flower quickly, many people associate them to autoflowering strains, as they also have a much shorter flowering period. However, they’re notably different from one another.

As their name indicates, autoflowers start flowering automatically, usually between 3 and 4 weeks after planting. In contrast with photo-dependent and fast strains, they don’t need any change in the light cycle for their vegetative period to end and the flowering to begin. Therefore, they need less interference from growers and are much easier to manage. Their main disadvantage is that plants usually grow smaller and produce lower yields.

Photo-dependent strains tend to produce larger and more productive plants that develop more potent buds. But they also involve more work and take much longer to grow. Most will vegetate indefinitely in a light cycle that ranges between 18/6 and 24/0 hours (of light to darkness). The flowering can be activated by changing the photoperiod to 12/12. This helps control the duration of the vegetative period and extend it to give rise to larger plants and higher yields. However, these plants also need longer to grow properly: the average growth time for photo-dependent strains is about four to six months after sowing.

Fast flowering cannabis plants also require a change in the photoperiod to start flowering; but, unlike traditional photo-dependent plants, they grow faster, and are ready to start the flowering phase in a maximum of eight weeks.

They also grow into larger and hardier plants than autos, which eventually rewards growers with heavier yields and more potent buds. Like with photo-dependent varieties, the flowering phase can be started by changing to a 12/12 light cycle, although fast varieties are usually ready for harvest several weeks earlier (between late August and early September in the northern hemisphere when planted outdoors).

What are the advantages of fast flowering strains?

Hitting a sweet spot between photo-dependent and autoflowering strains, fast flowering genetics have a lot to offer. Growers who try them for the first time will be sure to notice a wide range of benefits:

• Higher yielding capacity than that of autos: With a longer vegetative period, fast strains can produce larger and stronger plants with higher yielding potential and higher cannabinoid levels.
• Faster completion time: Their fine-tuned genetics means that they’re ready for harvest between 1 and 2 weeks earlier than standard photo-dependent strains.
• More harvests per season: The time saved allows for more growing cycles within the same period. For many growers, this opens the possibility of growing multiple harvests in a single season.
• Lower costs when growing indoors: Shorter flowering times also mean less time under the lights, which translates into savings on the electricity bill as well as on nutrients.
• They can be reproduced by cuttings: Unlike autos, fast flowering strains can be made into cuttings to create new mother plants that maintain the same flowering speed.
• Fast flowering traits are strengthened in later generations: Desirable attributes are often diluted when one variety is crossed with another, particularly if the alternative characteristics are more dominant in the other parent. But fast flowering genetics get stronger as they are passed down, which makes fast versions excellent parent strains.
• They can be grown in almost any climate: Many autoflowering and photo-dependent strains struggle to grow in cold and humid climates, high mountain areas, or regions with harsh winters. But fast flowering cannabis seeds produce robust plants that can thrive in almost any indoor or outdoor environment. And the possibility of harvesting earlier also helps producers to avoid the harshest parts of autumn.
• Compact plants: Many fast flowering cannabis varieties are usually indica (as these naturally have a shorter flowering time than sativas), so they turn into compact plants which are ideal for discrete grows and small growing spaces.
• Plants are hardier: Many fast flowering strains exhibit great natural resistance to mould and pests. Earlier flowering times also allow outdoor growers to avoid the bud rot that’s associated with the rainy season.

How to grow fast flowering cannabis strains

Thanks to their great versatility, Fast cannabis strains can be grown both indoors and outdoors. If you grow in pots, make sure you select a good size: they may not grow as much as photo-dependent plants, but they will certainly grow more than autoflowerings, so finding the right size can be tricky.

Having said that, you can treat them like photo-dependent strains and use the same type of pot. And they can grow much more when planted in soil: the more space they have for their roots to develop, the larger they will become.

Nevertheless, as with photo-dependent cannabis plants, you’ll have control over the size of Fast plants if you grow them indoors. Despite having a short flowering time, you can extend the vegetative period for as long as you want so they can reach the desired height; or otherwise switch to the flowering earlier if you want to harvest sooner.

Top tips to optimise the yielding capacity of Fast cannabis strains

Here are some tips to simplify the growing process of Fast cannabis strains:

1. When it’s time to select your Fast genetics, make sure you choose seeds from seed banks like Kannabia that have already stabilised the genetics of these varieties. This will ensure that you only grow quality seeds and avoid problems during cultivation.
2. Bear in mind that Fast plants tend to be slightly smaller than their photo-dependent counterparts, unless you let them grow for longer during the vegetative phase. To overcome this, it is recommended to use training methods like ScrOG (Screen of Green), Super Cropping, Topping, or LST (Low Stress Training).
3. If you’re going to grow Fast strains hydroponically, you must take factors such as humidity and temperature into consideration. As these plants have a shorter flowering period, you’ll have a little less time to solve any type of problem.
4. Some growers opt for a 24 hr light cycle during the vegetative phase so the plants grow further. However, this isn’t recommended because the plants also need some rest to recover from stress so they can grow healthy.
5. Add sufficient nitrogen during the vegetative stage, and a little phosphorus before the flowering phase, to give some extra oomph to the plants. In addition, if you have powerful grow lights with high light intensity, you can also use CO2 to increase the yield.
6. Growing fast flowering marijuana plants in coco coir is the perfect combo, as this type of substrate consists of approximately 25 – 30% air, which helps the roots to better absorb oxygen and gives them more space to grow. A large root system leads to a healthy flowering phase which can sometimes be faster as well, so your plants can grow and become stronger in less time.
7. Watch your buds constantly, as these Fast versions finish sooner. Don’t harvest them too early or too late. Use a magnifying glass to see if at least 70% of the trichomes have turned from transparent to milky. Having said that, some producers prefer harvesting earlier, when 50% of the trichomes have turned amber. Either way, it’s certainly better not to wait for too long as the buds’ THC count may start to decrease.

Why should you try Fast cannabis seeds?

There was a time when growing fast flowering cannabis meant compromising on yields or even quality. But nowadays that has changed massively. Meticulous experimentation and breeding have led to a range of strains that promise uncompromising speed… Fast flowering and high yields are no longer competitive features. At the perfect midpoint between autos and photo-dependent strains, fast varieties are the best of both worlds when it comes to feminized cannabis genetics.

Where to buy the best fast flowering seeds

The Kannabia team saw the need to develop this type of strains to minimise the risks during the last few weeks of flowering outdoors, when the autumn rains start and buds become denser. And the result is two new genetics that have been launched in 2024: Pure Skunk Go Fast, a classic revisited and optimised to deliver massive yields with an 8-week flowering period; and Candy Cream Go Fast, a strain that exudes the flavours of the newly minted American genetics, but in this case is ready in just 7 weeks of flowering.

If you still haven’t tried the great possibilities of these fast strains, then now’s the time to do so thanks to these new additions to our seed catalogue… Two genetics that promise a new twist to the way marijuana is grown.