How to know if a weed seed is autoflower

How To Tell If You Have An Autoflower vs Photoperiod Plant

Growing you own weed can be extremely rewarding and it’s a whole lot of fun too. That said, there are certain challenges which every home pot grower faces.

Of course, it all starts out with the cannabis seed, which needs to be germinated, planted, cared for, harvested, and more. (it’s well worth picking up this FREE grow bible, it has some great information).

However, something you might not know is that there are different kinds of weed plants out there, specifically to do with going from the vegetative to the flowering stage. There are photoperiod weed plants and autoflower weed plants, and there is a difference between the two.

So how to tell if you have an autoflower weed plant or a photoperiod weed plant? here is everything you need to know to tell the difference;

Autoflower vs Photoperiod: Differences

Before we get into talking about how you can tell if you have an autoflower or a photoperiod pot plant, it’s probably helpful for you to know what each one is.


So, first off you have the photoperiod weed plant, which can take up to 4 or even 6 months to fully grow.

Photoperiod refers to the amount of light or illumination a specific plant needs on a daily basis in order to grow. Photoperiod weed plants will stay in their vegetative state for as long as you provide them with ample daily light.

Generally speaking, photoperiod weed plants need between 18 and 24 hours of light per day during the vegetation stage.

In order to begin the flowering process, photoperiod weed plants require the amount of daily light to be decreased to 12 hours.

This change in lighting then causes a chemical reaction in the plant which signals that it is time to start flowering.


Autoflower weed plants grow much faster than photoperiod weed plants, and often only take 2 months to get from seed to harvest.

Now, just as the name implies, autoflowering weed plants start flowering all on their own when they are ready. This is regardless of lighting.

Therefore, they tend to be much easier to grow, less time consuming, and more beginner friendly.

This is because the grower does not have to make any changes to cause the weed plant to go from the vegetation stage to the flowering stage. With autoflower weed plants, this transition happens all on its own.

6 Ways To Identify An Autoflower Cannabis Plant

Alright, so now you probably want to know how you can tell if you have an autoflower weed plant, which is what we are here for right now.

Here are the best ways to tell if you have an autoflowering marijuana plant;

1. When You Buy the Seeds

The first way to tell if you have an autoflower weed plant is when you buy the seeds. Simply put, it’s best not to use seeds you find in your weed or to use seeds that are not labelled.

When you buy marijuana seeds from a professional place, they should always be labelled (here is a list of seed banks we recommend).

When all is said and done, you should know if your weed is autoflowering or photoperiod before you germinate your seeds, as this will determine how you treat the plant during growth.

However, you might not always know, which is why below, we have a list of ways to tell if your weed plant is autoflowering or not, all from the look of it, how long it takes to grow, and some other factors too.

2. The Size of The Plant

One of the main ways in which you can tell if you have an autoflowering weed plant is by the size of it. Generally speaking, because photoperiod plants grow longer, they also grow bigger.

In other words, autoflower weed plants tend to be much smaller than a photoperiod weed plant. Photoperiod weed plants can grow to 6 feet indoors and up to 10 feet outdoors.

On the other hand, an autoflower weed plant will usually top out at 3 feet in height indoors and 5 feet outdoors.

If you have been growing the weed plant for a full month and it’s still only between 1 and 2 feet high, chances are that it’s an autoflowering plant.

3. How Fast it Grows

Something else that can help you tell whether or not you have an autoflower plant is by the growth rate.

A photoperiod weed plant can take up to 8 or 10 weeks in the vegetation state, and then that long again in the flowering state.

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Therefore, a photoperiod weed plant can take up to a half a year to go from seed to harvest. So, if it took you any longer than 3 months to get to the harvest, it’s probably not an autoflowering plant.

However, if you planted your seeds and are ready to harvest buds within 10 or 12 weeks of planting, chances are almost 100% that it’s an autoflower weed strain.

4. Automatic Transition to Flowering

The easiest way you will be able to tell that you have an autoflowering weed plant is if it makes the transition from the vegetation stage to the flowering stage on its own.

A photoperiod weed plant requires you to reduce the amount of light given to it in order to start flowering. Without a reduction in daily lighting, a photoperiod plant will simply continue on vegetating.

However, an autoflower weed plant will begin flowering on its own regardless of lighting. Withing 4 to 6 weeks of having been planted, an autoflowering plant will automatically transition to the flowering stage all on its own.

5. The Final Yield

Yet another way to tell if you have grown an autoflower plant is by the final yield. Yes, photoperiod plants grow for much longer and they get much bigger, and therefore they also produce a much larger final yield.

On average, a photoperiod plants can yield up to 700 grams per square meter. When growing indoors, you can expect a single photoperiod weed plant to produce anywhere from 6 to 12 ounces of weed.

On the other hand, an autoflower weed plant will usually produce no more than 500 grams per square meter. Your average autoflower plant will produce between 2 and 6 ounces of bud by harvest time.

6. Potency

Yet another way to tell if you grew an autoflower or a photoperiod weed plant is by the potency of it.

For the most part, photoperiod weed plants will always be much more potent than autoflower plants, with THC content differences as high as 15% or even 20%.

Now, we do have to say that it all depends on the specific strain and growth conditions too. If you choose a naturally potent autoflower strain and you grow it like a pro, it might end up being more potent than a naturally weak photoperiod strain that has been grown improperly.

Although, this is not often the case.


When all has been said and done, if you want to grow some weed, but don’t want to take 6 months until you can smoke something, you want to go with autoflowering plants.

No, they might not get as big or produce as much of a final yield, but they are much easier to take care of and take about half as long as photoperiod plants to get from seed to harvest.


My passion for the sticky icky started nearly a decade ago, and it all began when I first laid my eyes on the beauty that is the marijuana plant.

I cover all aspects of growing from equipment recommendations to plant health/care tips to help both new and experienced growers.

The Lifecycle of the Autoflowering Cannabis Plant

Growing cannabis isn’t child’s play. You’ll succeed only after mastering the basics, and it’s even more important to familiarize yourself with the lifecycle of the plant.

  • 1. Germination
  • 2. Seedling stage
  • 3. Week 1 to week 3
  • 4. Week 4 to week 6
  • 5. Week 7 to week 9
  • 6. Week 10 to week 11
  • 7. Harvest
  • 8. Drying and curing
  • 9. In conclusion

Growing cannabis is an art that requires patience. Only growers that understand the science and lifecycle of the plant will succeed. The rest either fail miserably or simply give up. It’s not uncommon for beginners to fail. And since practice makes a man perfect, keep at it until you finally harvest a big bunch of nugs that remind you of all the hard work.

I promise that it’s all worth it in the end. But first, you must understand how the plant grows. Not only will this help you save time, but you’ll also be able to bounce back even if you face setbacks. So, let’s take a look at the lifecycle of the autoflowering cannabis plant to make it a little easier for you.


The first step of the plant’s cycle starts with germination. Now that you’ve grabbed your favorite seeds, it’s time to plant them. People use different ways to germinate the seeds, but it’s important to stick to a method that works for you. Ideally, the seeds should be soaked in a glass of water for at least 24 hours. Some growers use a nail file to scratch the seeds gently before soaking them.

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This ensures that the seeds soak in more water, but you shouldn’t attempt this if you’re a beginner. The seeds can then be transferred to a wet paper towel and stored in a zip-lock plastic bag. Within 1-2 days, the taproot emerges and the seeds are ready to be planted. Note that many growers simply stick their seeds in the soil, and you can follow the same route if you prefer.

Seedling Stage

The seeds can be transferred to the soil at this point. It may take another day or two for the seeds to emerge from the soil and break their hull. Be patient and stop messing with the plants. You might be tempted to assist the seedling since it looks so fragile, but it will do fine without you. Also, remember to regulate the pH as it’s very important.

The seedling stage is the most important stage. The plant will take a long time to recover if there’s a mishap at this stage, so be very careful. If growing indoors, hang the lights at least 17-20 inches above the seedling. Reduce the distance as the plant grows bigger. CFLs, LEDs, MH, and HIDs will do as long as the seedlings are comfortable.

Week 1 to Week 3

The seedlings begin with only two true leaves. After a couple of days, a third leaf will appear. The plants don’t need any nutrients on the very first week if you’re growing in soil. For those growing in hydroponic setups, reduce the strength of the nutrients by half to allow the seedlings to adjust to them. You can kill the plants faster by overwatering them. Not a myth; it’s a fact. So, go easy on watering. And, make sure that you supply enough water to keep the soil moist. Moist, not dripping wet or dry. As the process of photosynthesis goes on, new sets of leaves will appear.

The seedlings become a little stronger during week 2. You can now introduce nutrients unless you’re using premade organic potting soil. Again, the nutes should be mild as the plants are still fragile. The distance between the lights and the seedlings should be reduced if the seedlings grow lanky.

By week 3, the seedlings show more leaves popping up. Some autoflowers may display their sex at this stage, but if you’ve planted only feminized seeds, you don’t need to worry at all. If using regular seeds, however, it’s important to distinguish between male and female plants. While female plants show their pistils, the males will produce little pollen sacs. It’s a good idea to remove the males since sensimilla buds are preferred. Nutrients can be used at regular strength now, but be cautious to check the plants for any nutrient burn. The seedlings will suffer a bit with low doses of fertilizer or nutrients, but they don’t recover quickly from an overdose or nutrient burn.

Week 4 to Week 6

This is the phase that determines how big the plants grow. You can use several training techniques including LST, Topping and FIMing to increase yields. Many growers make the mistake of introducing bloom nutrients as soon as the plant produces a few pistils, but that’s not how you do it.

Note that some plants may still be in the vegetative stage and nutrients must be provided at full strength based on autoflower feeding schedule recommendations. Also, this depends on the type of fertilizer you’re using. For instance, if you’re growing organically, use organic nutrients according to the manufacturer’s instructions, but make sure that it contains more nitrogen. If you’re using a brand that has two parts of Growth and Bloom fertilizers, use only the “Grow” part during week 4. Most brands of fertilizers provide the numbering of N-P-K to make it easy for you.

For example, if you’re using General Hydroponics, only FloraGro and FloraMicro (micronutrients) should be used during this stage. Remember to regulate the pH constantly when using nutrients, but if you’re using something like the pH Perfect from Advanced nutrients, for instance, pH can take a back seat.

All cannabis plants can have different sizes even if they’re the same age. Gorilla Cookies by Grey_Wolf.

Week 5 begins with the plants producing lush leaves with a few buds appearing slowly. Continue with the “Grow” nutrients even at this stage lest you want the plants to stop growing vertically. This is the stage where an explosion of growth occurs and you need to support it with nitrogen. Using more phosphorous or potassium at this point will force the plant to focus more on the buds rather than growing.

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Many growers use bloom nutrients as soon as they enter the 5th week because they are satisfied with the growth of the plants. Some plants like Green Crack and Gorilla Glue have the tendency to grow very large, so you might be tempted to use flowering or bloom nutes. However, the yields can reduce significantly if the plant isn’t allowed to grow to its full potential.

As you enter week 6, the appearance of buds is even more apparent. A little defoliation doesn’t hurt now. Defoliation is the process of removing extra leaves to provide more light to the lower parts of the plant. Don’t overdo it, though, because the plant relies on the leaves to receive nutrients. Continue with nutrients meant for the vegetative stage as the plant will shoot up vertically.

Week 7 to Week 9

The plant is all geared up for its flowering stage and bloom nutrients can be used at full strength. The buds will begin to swell and the unmistakable aroma of sweet cannabis will fill up your tent. The pistils will slowly change colors from white to a light brown or red, depending on the strain.

It’s also a good idea to use nutrients to boost buds to improve the quality. Organic soil growers can use dried and powdered banana peels to introduce more potassium to the soil. The vertical growth stops sometime during week 7 but the plant does everything in its power to increase the size of the buds.

As you enter week 8, the leaves start yellowing a bit, but there’s nothing to be alarmed. This is just a natural way of the plant indicating that it’s nearing the end of its cycle. Continue to use flowering nutrients even as you step into week 9. Don’t forget micronutrients that are added right from week 2. Defoliate the plants again if the bottom parts of the plants display small buds.

Week 10 to Week 11

The plant is almost at the end of its lifecycle. Stop using nutrients and use plain water to remove any chemical buildup. This practice is known as flushing, and it’s very important if inorganic nutrients are used. Flushing also ensures that your buds don’t taste or smell like chemicals and improves the quality of smoke dramatically.

By week 11, all the leaves start turning yellow. Most of the pistils turn amber, indicating that it’s almost time to harvest. Admittedly, many seed companies including Fast Buds tell you that the plant will finish its cycle in 8-9 weeks. And yes, they do finish in 9 weeks if you grow in a good growing environment. However, your plants may take a little bit longer depending on the growing conditions you provide.

I received one seed of this variety as a gift and I can say that this is an excellent quality as always. I think it will be a great product)


You can harvest the plants now by chopping them all one by one. Use sharp sterilized scissors to prevent infecting the buds. Don’t forget to use gloves, especially if you’re harvesting buds of the Gorilla Glue as they are notorious for oozing resin all over.

Drying and Curing

This is the last stage where the buds are dried and then stored in mason jars. They will last a long time if you take care of the humidity. Curing comes at the last stage, but it’s the most important one if you want top-quality buds. Do not skip this process because all your hard work will be for naught if you skip this one. Last but not least, wait for at least 2 weeks to cure the buds even if you’re tempted to smoke them immediately. Doing so will reduce the harshness of the flower and your lungs will certainly thank you for it!

In Conclusion

The lifecycle of autoflowering cannabis plants is basically the same as photoperiods. There are a couple of differences in how fast they develop and how they grow but most cannabis growers with a couple of grow cycles under the belt can definitely grow autos without any problem at all.

If you’ve grown autoflowers before feel free to share your experience with fellow growers by leaving a comment in the comment section below!