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The Difference Between Photoperiod and Ruderalis Cannabis

autoflower vs photoperiod
Posted by: Samuel Thomasino Category: Articles Comments: 0

The Difference Between Photoperiod and Ruderalis Cannabis

Whilst both photoperiod and ruderalis (also known as “autoflowering” genetics will provide a grower with high-quality bud, there are some major differences in the way each type of plant grows. When it comes to buying cannabis seeds, this is perhaps the most important decision of all, given the pros and cons associated with each type.

This article will clear up any confusion you may have about photoperiod and ruderalis types of cannabis by providing you with information on the two overarching families of cannabis plants.

A brief introduction is required before we delve into the nitty-gritty of differences below. Firstly, photoperiod plants. The ‘photo’ component of ‘photoperiod’ derives its name from ‘light’, thus photoperiod plants are those whose lifecycle revolves around a light period, or light cycle. Indica and sativa strains of cannabis are both members of the photoperiod family and so it should come as no surprise that photoperiod strains of cannabis are the historical, long-standing form of the plant.

Ruderalis, or “autoflowering” plants on the other hand are newer to the scene. This family of cannabis originates in the cold climates of Central Asia, Eastern Europe and Russia, where daylight hours are often short and the weather is harsh, resulting in a short growing season. As a means of surviving these climates, ruderalis naturally developed an autoflowering gene, meaning that it is not reliant on the same light cycle as photoperiod plants for flowering to commence.

The main difference between photoperiod and autoflowering types of cannabis

Basically, autoflowers will start to flower and produce bud with any amount of light, whereas photoperiod plants have to have a set light cycle of 12 hours light and 12 hours dark to begin flowering and producing bud.

Autoflowering strains have a set time limit to their lifecycle whereas a photoperiod strains lifecycle is determined by the grower. After around 3 – 4 weeks an autoflowering will automatically begin to flower, regardless of whether the grower is ready for it. This can be an issue for inexperienced growers as the plant may have had issues or not grown quickly enough to reach a suitable size with a decent root system to produce a quality yield.

There are some other smaller differences listed below, but the most important differences a newcomer needs to know are listed above.

photoperiod plants size

autoflowering plants size


This is where the crucial differences lie for growers with limited space, time or resources.

Photoperiod plants, as their name suggests, are very sensitive to light cycles. As explained above, they can remain in the vegetative stage indefinitely if exposed to a specific spectrum of light cycle (18/6 – 24/0). Photoperiod plants will not enter the flowering stage unless they are exposed to a light cycle of 12/12, or more than twelve hours of darkness per twenty-four hour period.

This sensitivity is great for growers who wish to manipulate the plant’s development, for example by keeping it in a vegetative state until they are sure that it is ready to enter the flowering stage, thus maximising the amount and the quality of bud produced. Additionally, the longer growing period, particularly in the vegetative stage, means that photoperiod plants are more resilient to stress such as imbalances of water or light. This makes them easier for novice growers, as any mistakes can be redressed before the plant enters the crucial flowering period.

In comparison to photoperiod plants, autoflowering plants are much easier in some respects, though more difficult in others. As their name suggests, they will flower regardless of the light cycle to which they are exposed, so there is no need to set up timers, or otherwise manually manipulate the flowering period. They are also much easier to grow outside. However, the shorter lifecycle of autoflowering plants means there is less room for grower error, and they are more susceptible to stress.

The autoflowering plant has a few final positive points to consider. It is much more resilient to blights such as moulds and pests and grows shorter than its photoperiod counterpart, making discrete growing much easier.

The Growing Process

Autoflowering plants have a significantly shorter lifecycle than their photoperiod counterparts. Most photoperiod plants take around three months to produce harvestable bud. This consists of approximately one month of vegetative stage whereby the plant is putting down roots, absorbing nutrients, and growing above ground, followed by a two month flowering period. Some strains are much faster to flowering than others.

It is important to note that photoperiod plants can remain in the vegetative stage indefinitely if they are exposed to a light cycle of between 18/6 (18 hours of daylight and 6 hours of darkness in a twenty-four hour period) and 24/0.

In contrast, the autoflowering plant can produce harvestable bud around two to four weeks quicker than a photoperiod.

THC Content

In the past, photoperiodic plants produced bud containing a much higher THC content due to their longer flowering period. However, as the strain has developed, the disparity between the two has lessened dramatically, meaning that some autoflowering strains now produce similar high THC levels to their photoperiodic counterpart.

CBD Content

Though the disparity between THC levels has been reduced dramatically since the introduction of autoflowering plants, photoperiod plants continue to produce much lower levels of CBD. This is a significant advantage of growing autoflowering plants for medicinal cannabis users.


Due to the longer growing period for photoperiodic plants, combined with the fact that they can be more easily manipulated by their grower, photoperiod plants produce a higher yield of bud than autoflowering plants. Conversely, the shorter lifecycle of the autoflowering plant reduces its yield. By way of example, autoflowering plants will produce an average of 450-550 grams of bud per square meter, whereas photoperiod plants can produce an average of 600-700 grams.

Of course, the shorter lifecycle of the autoflowering plant counterbalances the lower yield, as over time, more harvests can be cultivated.


It is widely acknowledged that bud from photoperiod plants has a far superior aroma and taste to that from autoflowering plants. This is partly the result of the shorter flowering period of the autoflower, and partly a consequence of its relative newbie status, and hence less developed breeding. However, the autoflower gene itself is widely agreed to be inferior in flavour compared to the photoperiod varieties. However, as time goes on these shortcomings are being worked on and will most likely not continue to be an issue.

Seeds vs Cloning

Autoflower plants can be successfully cloned, but the clones will still be in the same stage of the mother plants life cycle. By the time the autoflower plant is big enough to take cuttings and the grower has got them successfully rooted, they will already be flowering. There will not be any time for the cuttings to grow into proper plants. Therefore more seeds are required for each new crop.

Photoperiod plants however can be very successfully cloned from the mother plant, meaning that an unlimited number of plants can be cultivated without having to continually purchase seeds. This cloning ability is particularly useful for retaining consistency in terms of flavour, potency, and quality of the harvest, as well as healthy plant genetics.

The Big Decision

Having examined the differences between these two families of cannabis plant, it is clear that there is no outright winner. Rather, the specific preferences of the grower should guide the decision. Both types of cannabis can produce incredible results so many people tend to alternate between both. Some people find autos to be less reliable in terms of mutations and stress related issues, but the quicker harvest allows more rotations to be brought down per year, making them a very tempting choice!

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