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If you’re a cannabis grower, you understand that vegetative plants need 12 hours of light and 12 hours of darkness to trigger the flowering stage. However, plants with naturally long flowering stages like pure sativa strains can benefit from 13 or 14 hours of darkness each day.

Setting your indoor plants in an 11/13 or 10/14 light schedule is a great way to trick your plant into thinking winter is coming soon and speeding up the flowering stage. Giving your plants longer periods of darkness can get them to mature much quicker than a 12/12 light cycle.

Speeding Up Flowering Reduces Yield

Faster isn’t always better. A significant drawback of giving your plants longer nights is the reduced yields. The amount of light your cannabis plants get affects their density, quality, and bud yield. Less light means reduced resin and bud density.

A light schedule with more hours of darkness than light can get your plant to complete its budding cycle sooner than the traditional 12/12 schedule. This means that you would be cutting its potential bud growth by weeks and affecting the final harvest weight.

Since going into a 10/14 light schedule reduces yields, some growers will allow their plants to flower for at least eight weeks before switching light schedules. This allows your buds to produce resin and become denser before getting a reduced amount of light.

10/14 Light Schedule for Landrace Sativa Strains

Generally, a 12/12 light schedule should be fine for most cannabis strains. If this schedule is working for you, keep it. One of the only reasons for switching to a 10/14 light cycle will be if you are growing pure sativa strains that take too long to finish.

If you absolutely cannot wait for your plant to finish its natural flowering stage, or you want to save some money on electricity, switching to a 10/14 light schedule may be a good idea. Just remember that light cycle switches should be made gradually. Consider transitioning from 12/12 to 11/13 and finally 10/14 throughout the flowering stage.

Best Light Cycle for Autoflowering Plants

Most cannabis strains are photoperiods, requiring 12 hours of darkness to start their flowering stage. Autoflowering strains do not require a change in the light cycle. They automatically start the flowering cycle when they are mature.

If you want to speed up your cannabis plant growth, going with autoflowering plants and alternative light cycles may do the trick. For these strains, growers may use any of these four primary light cycles.


More lights equal faster growth. This light schedule is suitable for those in cold climates. Twenty-four hours of light can keep your autoflowering plants warm. However, this schedule increases your energy bills.


20/4 is a popular light schedule because it sits between 18/6 and 24/0. Giving your plants resting time can produce better yields.


18/6 is the most common light cycle for autoflowering strains. If you live in a hot climate area, you can turn them off for six hours during the hottest part of the day.


12/12 is usually used for photoperiod plants but can work for autoflowering plants, although it is not as common. Growers may use this light cycle when growing photoperiod plants in the same tent. This light cycle can result in airy and tiny buds.

How to Determine Your Best Light Cycle

For the most part, 12 hours of light and 12 hours of darkness are the recommended light schedule during the flowering stage. However, various factors can affect how long you need to leave your plants in darkness before harvest.

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Consider how much electricity you want to use and adjust your light cycle. In addition, your region’s climate can affect how long you leave your lights on. Experiment with different schedules to find the best light cycle for your grow room.

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