What is 12-1 lighting?

What does 12-1 lighting mean, and how does it affect your marijuana yields?

For more information, this article by a guest author explains it in full detail what 12-1 lighting means in regards to growing weed.

The main idea is you give your plants the following light schedules:

Vegetative: 12 hours light, 5.5 hours dark, 1 hour light, 5.5 hours dark / day

Flowering: Start with 11 hours light, 13 hours darkness. You keep this for 2 weeks, then drop the lighting period by 30 minutes, I.E. after two weeks you will switch to 10.5 hours on, and 13.5 hours off. Continue this 30 minute drop every 2 weeks until you reach 9 hours on/ 15 hours off. Finish your flowering at this lighting.


In all plants the main growth happens during the light period as the plants turn energy from the light into energy to grow. So, due to this logic, it seems like this “12/1” method wouldn’t really result in increased yields because the plant is experiencing overall less light during all phases of growth, including the flowering period, which is when the plant is using all its energy to make bigger buds. That being said, there are many cases where what works for increased marijuana yields does not follow “common sense.” I’d be interested in seeing further testing on this method to determine one way or another whether this light schedule has any major benefits.

I first looked into this grow style after receiving the following comment about 12-1 lighting. This comment does not seem to provide any evidence that 12-1 lighting is effective.

“I have tried it for several months…. It is a different veg schedule. U go 12 on, 5 1/2 off, 1 on and then another 5 1/2 off. IMHO, at least for my set up there were to many variables causing stress especially a wild temperature change as the seasons changed to winter…yes even my basement gets a TON colder all winter. Quite frankly I had strain show herm characteristics after a while. Again there could have been stress with temperature and the strains at one time came from seed bank seeds and later given to me as clones. Who knows what factors came into play for my trial at 12/1, I gave it several solid months before I switched back to an 18/6. The biggest reason for the switch to it was the energy savings, the biggest reason for the switch back is I am a caregiver and I can not take any chances with other peoples medicine, if I fukk up more than just me go’s without….”

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