One of the most amazing breakthroughs in cannabis growing is the discovery of autoflowering cannabis seeds. This type of cannabis dramatically reduces the need to wait for marijuana plants to grow and flower. Usually, before growing autoflowering cannabis for the first time, growers as to how long autoflowering cannabis seeds grow to take to develop? This may be answered by using a simple comparison of regular or photoperiod strains with autoflowering strains. According to Grow Weed Easy, autoflowering cannabis plants are classified as cannabis ruderalis or simply ruderalis. These are unique plants because compared to regular seeds; you don’t have to use a specific lighting schedule to flower. Ruderalis plants start flowering when these reach 3-4 weeks of their life cycle. And as long as growing conditions are met, ruderalis plants will harvest a few months just after sprouting from seeds. 

How long Autoflowering Cannabis Seeds Grow? ~ a short history

How long autoflowering cannabis seeds grow? Auto-flowering cannabis strains came from a wild strain of hemp which was identified as “Ruderalis” in Russia. This happened during the early 1940s. These plants are very different from most strains of  photoperiod cannabis. Photoperiod cannabis doesn’t start flowering until they get hints from the surroundings that winter is coming. This kind of cannabis needs a special light schedule to start making buds. 

Auto-flowering strains begin to make buds when they’re 3-4 weeks old and are ready to harvest in less than 3 months from germination. There are even strains that can harvest quicker than this! Because of this very short lifespan, Ruderalis cannabis was able to live and thrive in frozen Russia. This region has very short summers and very long winters. However, the only downside is that ruderalis buds contain very little THC. Wild Ruderalis plants were also very small and with very small buds. But over the years, new breakthroughs were made and have improved the size of cannabis ruderalis plants and buds. 

A visionary breeder did not think that being small and having small yields made the ruderalis strain useless. He realized that the auto-flowering properties and short life spans of the ruderalis may be an advantage to hobbyist cannabis growers. This breeder experimented on mixing ruderalis properties with popular photoperiod strains. This increased bud potency and retained the plant’s autoflowering capabilities.  

Autoflowering strains or Lowryders are found at most marijuana seed banks that sell photoperiod strains. Wild Ruderalis contained almost no THC and were very tiny but modern auto-flowering strains produce buds comparable in potency to regular cannabis strains because of many generations of successful breeding.  

The role of genetics in creating autoflowering cannabis  

The original Ruderalis were small and were not as potent as with other autoflowering strains. The breeding history of strains changed this and is now responsible for small autoflowering plants with moderate to large yields. Breeders were able to make more specialized strains and have carefully calculated the positive and unwanted effects for various needs of the user.  

And because of this, each strain grows differently like photoperiod strains. Some auto-flowering strains have grown very tall while some stay short. Therefore you will be able to get the best results when you match the properties of each strain according to your growing setup.   

Auto-Flowering vs. Traditional Cannabis Strains 

Compared to traditional cannabis strains, autos don’t need any artificial light schedule for crops to start budding. Meanwhile, a photoperiod strain needs 12+ hours of darkness a day to start flowering. When growing photoperiod cannabis plants, flowering starts when the days become shorter. For outdoor growers, plants should be planted in the spring. You must also choose strains that will complete its life cycle in time before winter. To see how big do autoflowers get before winter.

On the other hand, Indoor cultivation of regular strains can initiate flowering at will. This is done by giving plants longer night time periods done by placing grow lights on a timer. For indoor growers, the grower needs to make a light-proof space to allow for 12 hours of uninterrupted darkness each day. 

When growing autoflowering cannabis plants, you don’t need to deal with changing light schedules. To see how big do autoflowers get. Each autoflowering plant starts flowering after a few weeks no matter what light schedule you place your plants in. For outdoor auto growers, you don’t have to match the strain with your local time zone or plant at the ideal growing time. All you need to do is to plant autos if there is at last 2-3 months of warm weather. 

If you are growing auto-flowering plants outdoors, there is no need to deal with special light schedules. Just make sure that your plants have 3 months of warm weather or temperatures above 60°F and your climate will grow auto-flowering plants. Auto crops will be ready for harvest before summer is done.  

How long to wait until harvest time 


Autoflowering seeds are ready for harvest sooner than photoperiod plants. Most autoflowering seeds will be ready for harvest in just 2-3 months after sprouting from seeds. For the initial weeks, autoflowering plants are in their vegetative growth. And after a short vegetative stage, the plant will make buds. These will soon continue to grow taller despite buds forming and maturing. At this point, auto-flowering plants will extend their energy into fattening buds. During the final few weeks, the buds will gain weight and will become denser as well.  

Therefore, when purchasing auto seeds find out how long the strain will grow until harvest. You must take note that most strain breeders will provide the shortest time frame and many autos will produce better yields if left for a week or two than the recommended harvest time. 

So when do you harvest? You must be mindful of a few factors as you grow your plants. Check the visual appearance of the buds by using a magnifier to find out if these are ready for harvest. This will also help you find out about the buds’ THC amounts.  


Photoperiod strains can take longer to harvest compared to autos. Photoperiod strains will be ready to harvest in just 3 to 4 months after sprouting from seeds to harvest time. Even photoperiod plants came from seeds and this will take longer compared to autoflowering plants with lower than the usual amount of yields. Photoperiod plants grow best when provided with the best growing conditions during the vegetative stage before these enter the flowering stage 

Which Yields More? 

Auto-Flowering Strains 

Autoflowering cannabis plants will yield up to 4 ounces of dried bud per plant when these are provided with the best growing environment. Therefore, the developing set up plays a huge role when growing regular or auto crops.  

Many growers yield 1-2 ounces per autoflowering plant or less. When you are starting with poor genetics or a sub-par lighting flowing and harvest time can take longer. Like all cannabis plants, autos will need a lot of light for improved yields despite not requiring a lighting schedule. In some cases, growers with good growing experience will start from good genetics and the ideal conditions to yield up to 6 ounces per auto-flowering plant or even more. 

Usually, when you consider yields, remember that one of the advantages of growing auto-flowering cannabis strains is that you can enjoy two harvests in one year. The lifespan of each auto plant is very short and this allows you to grow more per year.  

Photoperiod Strains 

Photoperiod strains usually have a more variation in yields compared to auto-flowering plants. This is because photoperiod growers are more in control over the size, shape, and the yields of the plant. Outdoors, yields depend on your climate. If you live in warm and sunny weather with many hours of light you will produce plants with bigger yields. When growing indoors, the growing setup is the biggest determining factor for harvesting more yields than other known factors. 

How big will each plant get? 


Autoflowering cannabis plants stay short naturally. In most conditions, it is difficult to create large auto plants because of their short lifespans. These only grow bigger for about 1-2 months and the rest of their lives are spent on making buds larger, denser, and heavier. Usually, autoflowering cannabis grows 1-4 feet tall by harvest time but usually, auto-flowering plants will stay under 4 feet. The final height of your auto plants will depend on the strain you want to grow and whether this was exposed to strong light. You can also use plant training methods like bending tall branches over or using low-stress training to keep stretchy plants from becoming too tall to handle. 


Photoperiod strains can be may be trained to grow into a large or to a small plant. Do autos need an artificial light schedule to start making buds or a special light schedule? The answer is yes. Auto strains needs should get 18-24 hours of light daily for the best results.  

So how long do autoflowering cannabis seeds take to grow? The answer is just a few weeks and sooner than regular seeds. Good growth should be encouraged with good lighting, humidity, nutrients, watering, and other growing requirements.

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