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Home » My Autoflower Is Not Flowering. What Do I Do?

My Autoflower Is Not Flowering. What Do I Do?

Did you plant autoflowering cannabis only to find it’s not flowering? Don’t panic, and don’t throw it in the chipper just yet. With some know-how, you can coax your auto through the vegetative stage and still initiate flowering. Read on to find out what steps to take to save the day, and thank us later.

What is Autoflowering Cannabis?

There are two main types of cannabis plants when it comes to flowering. There’s photoperiod plants, and there’s autoflowering. There are differences between the two you should know if you’re new to growing marijuana.

Photoperiod Cannabis

Photoperiod cannabis relies on a change the light schedule to initiate the flowering phase. This means, for your plants to pack on mass and start producing those smokeable buds, cannabis growers need to adjust the number of hours of light the plants receive. This means lights off and more time in the dark. Doing this will effectively accelerate the growth cycle and force the plants into a state where they produce flowers.

Autoflowering Cannabis

Autoflowering cannabis doesn’t need a change in the light schedule to initiate the flowering phase. Most autoflowering strains were created by breeders to contain some Ruderalis genetics, meaning they have greater survival skills than photoperiod strains. Ruderalis strains grew in the wild and have adapted to survive in extreme climates and conditions over time.

This means a hardier, sturdier plant that needs fewer nutrients than photoperiod cannabis, less care (autoflowering cannabis still requires a degree of care) and does not rely on a dark period to initiate flowering. Autoflowering strains enter the flowering stage after a set period (think of it as part of the plant’s life cycle) rather than via any light manipulation to force the flowering phase.

Why would you choose Autoflowering Cannabis?

Put simply, autoflowering cannabis strains have numerous advantages over photoperiod strains. From their known resilience to their ability to enter flowering without aid, and a shorter flowering time, autos are a smart choice for beginners looking to take the hard work and headaches out of their cannabis grow. They’re arguably cheaper to grow as well, as they require fewer nutrients than photoperiod cannabis plants and tend to thrive without the same need for attention.

Better yet, some autos finish faster than photoperiod strains, so the potential to harvest a few weeks earlier appeals to many growers. That’s not to say there are no ‘cons’ to growing autos, though.

Autoflowering cannabis plants are almost always smaller than their photoperiod counterparts. The downside of that is that yields are typically smaller, too. However, this isn’t always the case, as high-yielding autoflowering strains are available. If high yield is essential to you, hop over to and check out our range of high-yielding autoflowering cannabis seeds.

Why your Autoflowers won’t Flower

When an autoflowering plant doesn’t enter the flowering phase, something’s gone wrong. But diagnosing the problem can be challenging, especially if you’re an first-time or inexperienced grower. There are numerous reasons why an auto may stall at the vegetative growth stage, and we’ll look at a few of these.


Start at the start. From whom did you obtain your autoflowering seeds? If you bought them from a reliable seed bank like Seedsman, you’ve as good as eliminated the risk of problematic genetics.

At Seedsman, we pride ourselves on only ever dealing with top-quality, tested genetics to ensure your products are reliable and grow into high-quality cannabis plants. Unfortunately, it’s practically impossible to ensure the result of every single seed, and there’s always a chance of the occasional failure. Sadly, this is just the nature of the beast when dealing with seeds; not all seeds will germinate successfully every time.

If you acquired your seeds from a less-than-reputable source, you’re dealing with a lucky dip of sorts in genetics. For this reason, there’s a higher chance of problems. Always buy your seeds from a trusted seed bank to take this risk out of the equation.


Are your plants receiving an adequate amount of light? For example, if you’re growing your autos outdoors, are they covered by shade for much of the day? If so, your plants will still likely grow but experience problems with flowering. Autos don’t require a lighting schedule as photoperiod strains do, but they still need light to do their thing. Check your growing environment to ensure your autos are receiving plenty of light; if they’re not, move them. You planted your autos in moveable containers, right?

Light Spectrum

Are your plants receiving the right kind of light? In the flowering phase, your autoflower needs warm light from the red spectrum to assist flowering. If you’re using a grow room, adjust your lights to ensure your autos are receiving adequate red.


Other factors can contribute to flowering problems with your auto, so it might be time to ask yourself if you’ve followed the correct care regimen for your plants. Consider your watering schedule – could you be overwatering your plants? If this is the case, you may have caused problems with the flowering process. This is because overwatering cannabis plants can lead to nutrient deficiencies, root problems, and slow flowering.

Resist the temptation to water your plants on a fixed schedule. Instead, water only when the substrate requires it, i.e. when the soil is dry.

PH Level

Another reason your auto may be shy about flowering is an incorrect Ph level. If the Ph in your nutrients is ‘off’, it’s likely to affect the plant’s ability to thrive and flower. It’s therefore wise to check to the Ph level and adjust accordingly. For example, pH levels are optimal if growing in soil between 6.0 and 6.5. Research your substrate of choice and look at ways to bring your pH to the recommended level for that particular grow medium.


A nutrient deficiency can undoubtedly impede your auto’s flowering abilities, so if you’ve been eyeballing or guessing nutrient levels, there’s a chance this is the culprit. Always ensure you know exactly how much to feed your plants when you begin growing, and don’t play fast and loose with nutrient levels.

cannabis nutrients

Dark Cycle Interruption

If your dark cycle is interrupted, this could cause flowering problems, as the excess light can interfere with the plant’s hormones. Something as seemingly insignificant as a light leak in your grow tent can cause issues with the flowering process, as it causes a hormonal imbalance that will confuse the autoflower’s internal clock. Make sure your grow area is completely immune to light interruption, meaning light period is light and dark period is entirely dark.

These are just a few reasons your autoflowering plants may be experiencing problems entering flowering, and remain in veg. Autos are typically more resilient than photo strains, but you still have to keep tabs on your growing environment to satisfy your plants’ needs.

How to Force Flowering with Autoflowering Plants

Autos usually enter the flowering phase by themselves around five weeks after germination. Think of it as if the Ruderalis genetics are programmed to flower and survive faster, as though they expect a shorter and more perilous growing season.

This fails occasionally, and your auto will stay in vegetative mode longer than you’d expect – past the point where flowering is cited to begin. This is when you could start to panic, cursing everyone and everything from your plants, your seed supplier, and even yourself. Instead of panicking and inventing a host of unique new expletives, take action.


Admittedly, this is probably not what you wanted to hear. Your first course of action should be to simply give your plants another week – or even two or three – to see if they catch up and enter flowering automatically as they should. Time may be of the essence, but unfortunately, on this occasion, a little patience on your part may be required.

Not all autos flower like clockwork; now and again, you’ll find one drags its heels a bit, and waiting it out rather than panicking is all it takes on your part. With any luck, the plant will simply be running late and enter flowering automatically a week or two behind schedule.

Adjust The Light Schedule

This course of action is counter-intuitive to what you bought autoflowering cannabis for, but if you wait it out a couple of weeks and still no flowering, all is not lost. Switch the light cycle to 12/12 – meaning 12 hours under light and 12 hours of darkness. This strategy is almost always enough of a catalyst to shock your autos into bloom.

Doing this will trigger your autos into thinking the season is shortening, and they will adapt by racing to the next stage – flowering. Check your plants at the nodes regularly for indication of pre-flowering. If you see white hairs and pistils appearing, you can relax.

Consider Your Maintenance Schedule

Is your environment all that it should be? Is the lighting, temperature, Ph, nutrients, watering schedule and so on all optimised for healthy autos plants to grow and flower? If not, you will have to look closely at each facet of your plant’s environment and your practices of cannabis cultivation. See if there is room for improvement. Keep training techniques to a minimum, and inspect your grow area for any signs of pests and pathogens.

These can cause problems for your marijuana plant, likely leading to flowering issues. Autos are resilient, but you should still monitor your plants for signs of stress.

autoflower cannabis week by week

Is it Possible your Autoflowering Plant is a dud?

It could be, but it’s often the least likely scenario. Identifying the root (sorry!) of your flowering issue is the hard part; once you’ve done that, you’ll have a better idea of how to fix it and ensure a happy, thriving autoflowering cannabis plant that delivers on its autoflowering promise.

Start with solid genetics, and research the necessary care for your chosen strain. If you follow those instructions, you’ll eliminate yourself from the list of reasons why your auto isn’t flowering. If you’ve cared for your plant the way you need to and it still doesn’t flower, try changing up the light schedule to 12/12, and you’ll likely find that makes the difference. Good luck!

Cultivation information, and media is given for those of our clients who live in countries where cannabis cultivation is decriminalised or legal, or to those that operate within a licensed model. We encourage all readers to be aware of their local laws and to ensure they do not break them.

Duncan Mathers