How Long Does It Take For Autoflowers To Grow From Seed?


Ah, patience is a virtue. How long does it take for autoflowers to grow from seed, you’re asking… In a rush, are we? Hey – no judgment here, we know the feeling.

“The longer it takes, the more you get” doesn’t quite work out for autoflowers. Under the right circumstances, this applies to cannabis plants you grow from feminized seeds. Female plants can be kept in a vegetative state to grow larger, and larger… They can also use this time to recuperate from potential mishaps. There is some wiggle room

However, since autos are genetically programmed to start flowering after a certain time has elapsed, you’ll really have to bring it on during this time, to ensure the most success. (And by most success, I think we all mean the largest yield, right?)


Seeds start by growing one small “tail”. This will become the first and most established root of the plant. It is called a taproot.

It usually takes anywhere from two to ten days before seeds sprout. Exceptions are certainly possible: some seeds are very eager and germinate in as little as twenty-four hours, while others may need up to two weeks to show a sign of action.

Based on personal experience, some seeds are super fast and others are so slow! It’s helpful to be patient and not give up hope too soon. However, if after three weeks nothing has happened, it is probably time to factor in a disappointment.

Tip: Some seed banks will send a replacement if seeds don’t sprout at all. However, they might request that you use a certain method in order to qualify for the germination guarantee. Be sure to check the fine print when you order seeds online. Read more: Where to Find Cannabis Seeds with Guaranteed Germination

Autoflowers in the Vegetative & Flowering Stages

Once seeds have germinated and are starting to grow, we speak of the vegetative stage. Autoflowering cannabis plants typically spend mere weeks in this stage, before they start to show the first signs of flowering.

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The flowering stage can be subdivided into early, mid, and late flowering. This accounts for when the first flowers appear, the time it takes for them to mature, and the final stretch during which they become ripe for harvesting.

How long does it take for autoflowers to grow from seed?

There are a lot of different strains. Especially the range of autos is ever-expanding – tailoring to a demand from the consumer. It may be clear that even among autoflowering strains, there is some variation depending on the genetic background.

Most generally speaking, autoflowering plants need about half the time, from seed to harvest, compared to their photoperiod counterparts.

Some autos are notoriously fast and can be ready for harvest around eight to nine weeks after germination. Others need more time – a total of twelve, thirteen, or even fifteen weeks is still considered ‘quick’.

If you get seeds from a reputable seed bank online, you’ll likely find some indication of the time frame on the website. Most companies include this information in the strain-specific description.

Remember that it is a living organism we’re talking about. There are so many variables in a plant’s immediate surroundings it responds to. All of those factors might affect how long it takes for autoflowers to grow from seed and how well they thrive.

ILGM has many great autoflowering seeds, as well as some fun mix packs (a curated set of three strains at a discounted price). They list a blanket time frame of ten to fourteen weeks as the total grow time for all (auto) strains.

Keep in mind that the higher-yielding autoflowers may be on the slower end of the spectrum. That’s right – you can have it quickly, or you can have more of it, but you can never have it all… Ah, life – eh?

Marijuana Growth Stages

If you want to get further into marijuana growth stages, this is a good read.

We’re not going as in-depth here, since we’re focusing specifically on how long it takes for autoflowers to grow from seed. The stages are the same for photoperiod strains, most of them are just longer. Once the seeds have sprouted and the taproot “hits the ground”, autoflowers have their eye on the ball and head straight for the finish line with unparalleled speed. The metaphorical ball here is producing offspring.

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The autoflowering gene comes from the Cannabis Ruderalis sub-species. Ruderalis plants are native to certain areas of central Europe and Asia, where the summer season is short.

Cannabis Ruderalis had to adapt to its surroundings and found a way to not be taken off-guard by the end of the season. Before the weather gets brutal, these fascinating plants are long done with their flowering cycle, because they didn’t wait around for queues from the dwindling light. Instead, they follow their internal clock and make the switch from vegetation to flowering after a set time.

Does Growing Indoors vs Outside Matter?

Does growing autoflowers indoors go faster than outside, or vice-versa? Not everyone has the ideal set-up to do one or the other, or even switch between both. So while the answer to this question is interesting on some level, it may not be all that relevant from a practical standpoint.

Let’s just put it this way: inside, you create a controlled environment for the plants. Ideally, this means they will get a perfect amount of light exposure to grow as large as they possibly can. If the space is somewhat limited, you have the option to experiment with low-stress training to maximize yield.

Even indoors, things don’t always go ‘right’, so it isn’t a sure win. Not to mention a portion of the power bill reflects to cost of all that artificial sunlight.

Growing outdoors, plants have access to as much free light as there is. Which, in turn, means they do depend on the erratic moods of the weather gods. Space is less likely to be an issue (unless, of course, you’re aiming to remain undetectable in a crowded area).

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The time it takes autoflowers to grow from seed to harvest is dictated by their internal clock. So either way, the time it takes the plants to reach the finish line should not be much different.

Obviously, the goal is to have these plants grow as large as possible, and remain equally healthy. The time it takes them to do so is set – growing inside or out does not change this. The deciding factor is what they are exposed to during this period, whether indoors or outside.

Grown inside, there is no limit to the number of harvests per year. Outside, autoflowers use the duration of a short growing season to perfection. So if limited time outside is all you have available, autos are your best friend.


One thing is certain: how long it takes for autoflowers to grow from a seed into full-fledged plants with flowers that are ready for harvesting is in no way related to a light schedule. The time it takes them to do so depends on the genetic lineage of the plant. There are many different autoflowering strains and cross-breeds, with a total growing time varying between eight and fifteen weeks, sometimes longer.

Since we have no control over the growth time of autos, they make a perfect project to learn the ropes of growing on all other fronts. When the growing season is short, autoflowers are an excellent choice – it is what they’re ‘built for’. (At least their autoflowering gene, courtesy of Cannabis Ruderalis, makes it so that they are.) If you have a longer growing season, autos might enable you to do multiple harvests.

By Felis Cannabis

Hi, Felis Cannabis here. This little corner of the web is my scratch pole. The legalize movement is growing, but not fast enough for me to give up the incognito status just yet. ;-) Let's keep at it! We should have the right to use any plant we choose.