Flower lighting change

4 white widow autos that I’m almost 100% sure are
pre-flower or flower stage. They have been on a 20/4 light schedule. Would you change it to 18/6 or 12/12 with them being autos?


It would depend on what you have for a light. If you can reach a good dli in 12 hours then it wouldn’t hurt anything. I actually like to run a 6/2 schedule for autos it seems like I get faster growth and they can handle more light. I don’t have a meter to check if it’s fact but it seems like it


@whtdrgn , do you have a par/ppfd meter or even the Photone App?

I would calculate out my dli for a 18/6 or 12/12 setup. The Photone App has that ability built in to it. You’ll want to shoot for 40-65 dli. 50+ dli would be a great place to be.

That should be the deciding factor for your light schedule


The cool thing about autos is that you shouldn’t need a 12/12 schedule for them to flower.

Daily Light Integral, as previous commenters have stated, is what’s important. This is the total sum of light delivered to the plant in one day. If you can run for more hours, you could deliver the same amount running at a lower intensity; or keep the intensity and get a higher DLI.

Above 50 though it’s my understanding that CO2 (+temperature) become a limiting factor.


Thank you for the app recommendation. 56 for 18. I will switch to 18.

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@whtdrgn even a 17/9,16/8 won’t hurt if you’re trying to save power.

I would go a 18/6 now they look great keep up the good work