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Photoperiod vs Autoflowering Marijuana Strains by EasilyUsed

When looking at cannabis seed options online, there are "photoperiod" and "auto-flowering" strains available.

What do these terms mean? 

Today, EasilyUsed breaks it down for you...


The Basics of Photoperiod vs Autoflowering Marijuana Strains
by EasilyUsed

Republished with permission, orginal article here.

Photoperiod Cannabis Strains

  • Will vegetate essentially indefinitely on anything between an 18/6 and 24/0 light cycle.

  • Can be cloned, one seed = unlimited plants.

  • Will flower once put into a 12/12 light cycle.

  • Usually will produce a usable yield in a longer amount of time.

  • Can produce a larger plant and therefore higher yield.

  • Will produce a more potent bud.

  • Can take more abuse due to unlimited vegetation period.

  • Responds well to topping and super cropping in the vegetative cycle.

Learn more about photoperiod strains

Autoflowering Cannabis Strains

  • Will vegetate for a limited amount of time before automatically going into flowering mode (each strain's vegetative time will be different).

  • Cannot be cloned (in the traditional sense), one seed = one plant.

  • Will flower automatically, regardless of light cycle.

  • Usually will produce usable yield sooner.

  • Will produce a smaller plant and therefore limited yield.

  • Will produce less potent buds.

  • Can't take much abuse due to limited growth time.

  • May not respond well to topping and super-cropping.

Both Photoperiod and Autoflowering:

  • It its natural state, cannabis is an annual plant. This means that these plants grow from new seeds every year, and die at the end of the flowering process, ideally mating, creating and releasing seeds that will grow as the next generation.

  • Can be stressed and hermie (grow both male and female parts) as a result of incorrect light cycle changes.

  • Seeds can generate male or female plants, unless the seeds are feminized.

  • Need the same amount of nutrient care.

  • Can potentially be grown to produce the same size plants with similar yields.

  • Respond well to LST and SCROG

Learn more about autoflowering strains

The in-depth differences...

Photoperiod Cannabis Strains

Glowing sparkly marijuana colaPhotoperiod cannabis is the 'industry' standard; it is the natural state of THC-potent cannabis strains.

Cannabis sativa and cannabis indica will vegetate almost indefinitely on anything between an 18/6 and 24/0 light schedule, and will only enter full flowering mode when its lighting schedule is limited to 12/12.

If planted outside, growing photoperiod cannabis is only viable "naturally" when planted at the beginning of the summer, naturally entering flowering mode at the end of the summer when the days become shorter.

Outdoor naturally grown cannabis will be ready to harvest in the fall (specifics varying depending on location, as daylight availability depends on your latitude). Outdoor cannabis will not grow naturally any other time of year without supplemental lighting and darkness.

Photoperiod cannabis may be easier to grow indoors for new growers because it can be abused in the vegetative state and have time to recover because it can be vegetated until the grower decides to change the light cycle to flowering.

The flowering process is generally thought to be the most delicate time for the plant; so the utmost care should be given to a plant in its flowering cycle.

Note by Nebula: In some instances, photoperiod strains of cannabis may be easier to grow indoors if you are a new grower because you can give yourself as much time as you need in the vegetative stage. During this stage, cannabis plants are hardy and can bounce back from problems. Even if you make a lot of mistakes, you can still get big yields because you are in control of when the flowering stage begins, unlike with autoflowering strains. Once the flowering cycle is initiated, your plants are more "set" as far as their overall health and structure. Once a cannabis plant starts budding, there is basically a countdown until buds are ready to harvest (this amount of time is mostly based on the strain). Though the plant may have an initial last "stretch" of vegetative growth when the light cycle is first changed over, as the plant approaches harvest towards the end of the flowering stage, almost all growth halts except the development of bigger buds.

Photoperiod cannabis can be cloned indefinitely. Cuts can be taken from photoperiod cannabis to create rooted clones of the plant at any stage, and can be vegetated into large plants before being put into (or back into) the flowering stage.


Quick Key to Light Schedules For Photoperiod (Non-Autoflowering) Strains

This key breaks down some of the terms used in the article below such as "24/0" or 12/12"

Vegetative - Indoor cannabis plants kept on these light schedules will display only vegetative growth

18/6 - 18 Hours Light / 6 Hours Darkness each Day
24/0 - 24 Hours Light / 0 Hours Darkness each Day

Flowering - Indoor cannabis plants on this light schedule will start growing flowers (buds)

12/12 - 12 Hours Light / 12 Hours Darkness each Day

Timer to turn lights on and off automatically* Most indoor growers use a timer to turn their lights on and off automatically.  

Vegetative vs Flowering Marijuana plant diagram


Autoflowering Cannabis Strains

Autoflowering cannabis is a human-created crossbreed of cannabis ruderalis and cannabis sativa and/or cannabis indica.

Cannabis ruderalis is a strain of cannabis that naturally will enter its flowering cycle based on a given time since its germination, regardless of light cycle.

This is in contrast to photoperiod cannabis, which will generally only enter flowering when the light cycle has been changed to 12/12.

Auto-flowering marijuana strains tend to stay very smallThe automatic flowering nature of ruderalis creates a smaller plant, as its vegetative cycle is naturally limited, whereas a photoperiod strain can be vegetated into a much larger plant before switching to a flowering light cycle.

Note by Nebula: The auto-flowering plant pictured to the left is 2 months from seed and has been well-cared for. This plant naturally stayed short and bushy and displays the classical growth pattern of most auto-flowering strains. This plant still has a few weeks before time-to-harvest, and buds will continue to fatten up.

Cannabis ruderalis is also a non-THC potent strain, so when it is cross bred with high-THC-producing sativa or indica, it retains some of the ruderalis properties, and some of the sativa or indica properties, leading to a lesser THC content than a strictly non-ruderalis strain.

Between these two traits, autoflowering strains will theoretically produce not only less bud, but also less potent buds.

Photoperiod strains that are flowered immediately or grown in limited root-space can produce similarly small-sized, quickly flowering plants, but they ought to have a larger THC concentration than their autoflowering counterparts. THC content is still a matter of debate between autoflowering cannabis proponents and detractors.

Autoflowering strains seem more user-friendly for new growers because of the absence of light-cycle decisions. This is a sort of fallacy, as new growers tend also to abuse plants more than seasoned growers.

Sick autoflowering plant doesn't have time to recover before flowering beginsNote by Nebula: The auto-flowering White Widow plant pictured to the right is sick and stunted. Because of the auto-flowering nature of this strain, the grower was unable to nurture the plant back to health before the flowering stage began. In this picture, the plant is 2.5 months old (started from seed like all autoflowering plants), and the buds are almost ready for harvest even though they're still small and airy. As a result, the total yields from this plant will be very low (just a few grams). This can be discouraging as the grower must start over with a new seed in order to try for a bigger harvest. 

Autoflowering strains will enter flowering (the most delicate stage of growth) regardless of their health.

Photoperiod growers have the choice of entering the flowering period whenever they choose, allowing them to choose this when their plants are healthiest, as well as allowing for more vegetative time for their plants to recover from earlier mistakes.

Autoflowering strains will enter the flowering stage in stressed or unhealthy states automatically, which can limit bud yields.

Autoflowering cannabis cannot be cloned in the traditional sense.

That is, autoflowering cannabis will always retain its 'internal flowering timer.'

If you make a cut of autoflowering cannabis, it can potentially root and create an independent plant, however, this clone will still have the internal clock set to the same automatic flowering clock as its mother.

The clone and mother will still flower at the same amount of time after the original seed they both came from was germinated. Given that autoflowering strains have a very short vegetation cycle, it is debatable whether or not you'd gain a larger yield from making a lot of small flowered clones from one auto or if you let the auto vegetate and flower into one large plant.

Along the same lines, the limited vegetative cycle does not allow for very much drastic growth techniques like topping and super cropping, as the plant doesn't have a lot of time to recover from these before it flowers.

Autoflowering cannabis can be grown outdoors any time of year (assuming it has a reasonable, stable environment in terms of temperature, etc), since it will flower with any light cycle.

Autoflowering cannabis can be grown outdoors in conjunction with photoperiod cannabis to harvest twice in a summer season; once quickly from the autoflowering, and later a second harvest from the photoperiod cannabis.

Autoflowering cannabis is thought to be best grown in anything between a 18/6 and 20/4 light cycle, as it gets a lot of light, but also has time to recover in darkness. It can, however, be grown in 12/12 permanently or 24/0 permanently.

Gorgeous auto-flowering marijuana buds


Proven Auto-Flowering Strains 

  1. Northern Lights +
    Sturdy strain is easy to grow and a good choice for first-time indoor growers. Performs very well indoors, naturally stays short/bushy, low odor, and potent buds just like the famous Northern Lights strain.
    - Best Indoors
    - Good for Beginners
    - Low Odor
    - Potent Buds Like Regular Northern Lights
  2. Short Rider +
    Great option for outdoor growers with very short summers as she's ready to harvest just 2-3 months after sprouting from seed . One of the original auto-flowering strains, with decent yields and a good buzz.
    - Best Outdoors (Short Summers)
    - Ready to Harvest in 2-3 Months
    - Pleasant Buzz
  3. Blue Mystic +
    Neutral odor while growing that is reminiscent of hay or flowers, and tropical fruity smell/taste after being harvested and cured. Given the right conditions (happy plants, cooler temps at night as you approach harvest), this strain often shows hints of blue or purple in the buds/flowers. Plants tend to grow a bit bigger than other autos and this strain usually needs a full 3 months of growth before being ready to harvest.
    - Indoors or Outdoors
    - Neutral odor while growing
    - Fruity / tropical smell after buds are cured
    - Buds often blue or purple
    - 3 months before ready to harvest
See Nirvana Northern Lights + in Action!
Autoflowering Northern Lights Strain by Nirvana
Incredible picture by pencilacademy

This plant is much larger than most auto-flowering plants, but shows what can be possible when auto-flowering plants are well taken care of throughout their life.