When to Use 12/12 Light Cycle for Your Autoflowering Cannabis Plants and Why?

light cycle autoflowering cannabis plants

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Cannabis plants are naturally light-hungry plants that thrive best when they are left alone under the bright sun. But when you are growing weed indoors, delivering just the right amount of light is crucial to its overall growth and development. You need to be consistent and provide light and dark conditions mimicking the plant’s natural growth.

Growing autoflowering cannabis plants is no exception. These plants need as much light as they can get to commit to its early growing stage of 3 weeks and harvest in just 8 weeks. This earlier growth is engraved in autoflowering plant’s genetic makeup and because of this it needs between 18 to 24 hours of light every day. But what if light requirements were shortened to 12 hours? Could an auto survive?

Many growers and expert breeders agree that a 12/12 cycle is possible for autoflowering cannabis and that they can still create good buds however, the yield would suffer dramatically. Compared to autos grown in 18/6, 20/4 or 24/0, a 12/12 will have a small yield because its light requirements were reduced by almost half of its ideal requirements.

Reasons for a 12/12 Cycle

Sometimes growers have no choice but to adhere to a 12/12 cycle and these are the most common reasons why

  • Growing autoflowering cannabis outdoors

You won’t have much choice in lighting cycles when you are growing autos outdoors. Nature has plans for your seeds and it is under a 12/12 natural light cycle where your plants will receive equal amounts of light and dark conditions. Apparently this is what the earliest cannabis plants get as they grow roughly in the wild. Apart from a 12/12 cycle, outdoor plants also receive natural wind, water and moisture and organic food from the soil. It’s no wonder outdoor cannabis is more potent and preferred by more users.

And of course outdoor growing is not as perfect as it may seem. Along with a 12/12 cycle comes uncertain amounts of rain; possible attacks of rough winds, potential rouge pollen that can pollinate your crops and of course the dangers of your operation being exposed. All these dangers could be detrimental to your crops as well as your safety and this is why more breeders and growers pretty much prefer indoor growing than outdoors.

  • Growing autos with photos together

Growing autos and photos together is possible and in this situation, your autoflowering cannabis plants will have to give way to photos’ unique light requirements. You can grow autos in one area of the flowering chamber and photos in the other part of the chamber. Autos will be able to provide you with decent bud even before your photos mature.

These two plants get 24 hours of light each day from day one. Then you can switch to a 12/12 when you want your photos to flower. Autos will not be affected by this change and this won’t stress them at all. Contrary to popular belief, this light change won’t cause hermaphrodite plants to develop.

  • Growing autos in a hot environment

If you  live in an environment that is just too hot all day long then you have the perfect opportunity to use a 12/12 cycle in your grow room or tent. Simply power off your lights in the afternoon when temperatures get too hot and turn your lights on when ambient air becomes cooler. With this lighting schedule, you will still be able to get great buds.

  • Growing autos with bad genes

Not all autoflower cannabis plants come with a guarantee. Some plants may come with bad genes and refuse to grow and flower after 3 to 5 weeks. Why supply this bad batch with 24 hour lighting when there is no use looking forward to an early harvest? It’s better to cut your costs and just switch to a 12/12 lighting cycle. Adjusting to 12/12 after 3 to 6 weeks will also kick start the plant’s flowering phase so it’s definitely worth a try.

  • Growing autos while cutting electricity costs

It’s really tough growing indoors with all auto’s environmental requirements including non-stop lighting. High powered lamps alone take a large portion of your electricity bills and of course don’t forget your ventilation unit, water pumps, fans and other electronic monitoring devices that also eat up electricity every day. It’s definitely smarter to reduce light cycles to 12/12 to cut down on costs.

There are also some disadvantages of using a 12/12 cycle; the most common disadvantage is you will get slower growth. Autos need a lot of light and with a 12/12 cycle they will grow slower and won’t be able to grow with more branches and leaves. In short, you will get a smaller plant and a plant with less leaves and less fluffier colas. Some autos will still have abundant leaves and fluff but will have a longer growing cycle. There are growers that have noted 30% longer growth on their autos under the 12/12 cycle.

Plants will also tend to stretch to the light source just to get more light when you use a 12/12 cycle. You will also see plants creeping into cracks and openings that leak light into the grow room in an effort to get more light. Unwanted stretching results to weakened branches and stress to plants. In short you are adding more stress resulting in poor yield and poor growth as well. Finally, there is no doubt that autos exposed to 12/12 light cycles get lower yields.

Experts believe that if you must use the 12/12 cycle then you must stick to this routine from start to finish just to give your plants consistency and less stress. You can also use a 24/0 or 18/6 cycle during the vegetative state and gradually reduce to a 12/12 cycle when you see the first preflowers appear. This way, the plant growth and yield won’t be too affected by your new lighting condition and most importantly, plants won’t be in a state of stress.

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