INDOOR Clones ---> OUTDOOR Grow: **Light Question**

I want to keep my plants from flowering. They’ve had a lot of light up til now (18-22hrs) and I’d like to go to the local daylight (14+ hrs) only. I’ve been keeping them outside during daylight and lighting them indoors at night for about 6 hours.

The core question is about Light Triggering Flowering:

  • Is it the CHANGE in the amount of light…
    From 18-22 to --> 14 or 13+hrs
  • Or is it the actual AMOUNT of light… that triggers flowering.
    If I keep them above 12… 13… hours will they not flower, no matter how much light they’ve had up to that point?

If I go from 18-22 hours (daylight and LED) to --> 14 hours of daylight only, will that trigger flowering? Again, I do not want them to flower.

Will the CHANGE from 20 hrs to 14 hrs trigger flowering,
Or, as long as I stay longer than 12? hours will they not flower?

Here’s the history:
The Clones:
Green Crack and Big Bud
Seller kept them at 18 hrs of light, from seed to sale.
Juvenile Grow - Now 18"
6 weeks with 18-22hrs of light
I would like to just let the sunlight take care of it: 14hrs, 15 min.

If they keep from flowering I plan to start adding light in August to keep them in light for at least 13-14? hours. My goal is to induce flowering in September when it gets much hotter and the ocean fog/overcast disappears (to avoid mold in buds).

What to do…???

Not sure where you are located, but 14 hours and 15 mins is fine to keep them from flowering as long as your days are getting longer. When it drops below 14 hours they will start to start to flower.

I recommend you match the outdoor day light hours indoors before moving out and I normally transition for a week before going into direct sun since you have been keeping them outdoors your probably not going to need to transition yours
14-15 hours will keep them from flowering but you will see signs of maturity and they will let you know they are ready


It’s not the length of the day that makes them flower. It’s the length of total uninterrupted darkness. It’s a hormonal thing, and even twilight keeps the flower reaction from starting. If you can go out and shine a flashlight on them every night for 15 minutes around midnight, they will not flower.

Thank you for responding!!

What I’m understanding:

  1. It sound like plants need over 14-15 hours of light to keep from “showing signs of maturing”.
  2. By “hours of light” that really means a corresponding number of hours of darkness - uninterrupted darkness.

Conclusion V1:

  1. Be sure the uninterrupted darkness is less than 9 hours. That equates to over 15 “hours of light”.
  2. To be safe, there should be no more than, say, 6 hours of uninterrupted darkness, corresponding to 18 hours of some kind of light.
  3. I can keep them outside and give them 4 hours of uninterrupted darkness and that will match the amount of “some kind of light” they’ve been used to, about 20 hours.

What do you think of this PLAN?:

  1. Keep them outside and hit them with timed light (normal incandescent vs the striking, noticeable color of grow led) about three times between 8pm (sunset) and about 2AM (sunrise here is 6AM in July). Light stays on for 20 minutes each of the three times.
    (I know 1BigFella said all that’s needed is 15 min at midnight, but I want to be safe…)
  2. This should provide no more than 6 hours of uninterrupted darkness which equals about 18 hours of light.

**Is this close enough to work, to keep them from switching to flower/maturity?

Thank you so much!!

Anyway you do it is up to you. Just break the natrual light cycle hours by at least 15 mins like big said. If you do it around the middle of the night one time it’s the easy way to split the dark hours.

Cool… thanks. I often end up complicating things.

Take care, gents.