going from 20 hrs light to 15ish

imgrowing · May 6, 2025

turned the timer up to 20 hrs light for photos. how long should i leave them inside before i put them outside to start flowering?
current sunlight hrs are 14 hrs 50 min here and getting longer until june 21 which will be 16 hrs sunlight.
1st time doing photos outside so i have no clue, southern vancouver island.
i want them to start the transition to flower asap once outside

RoadKillSkunkHunt · May 6, 2025

imgrowing said:
turned the timer up to 20 hrs light for photos. how long should i leave them inside before i put them outside to start flowering?
current sunlight hrs are 14 hrs 50 min here and getting longer until june 21 which will be 16 hrs sunlight.
1st time doing photos outside so i have no clue, southern vancouver island.
i want them to start the transition to flower asap once outside

You can put them outside if the weather is fit for plants. Warm days with night time temps in the upper 60s/low 70's is ideal.

I know nothing about Vancouver Island. Are you beyond the danger of frost?

Edit: When does your day length drop back below 14hrs of daylight? That's the time when most outdoor photoperiod plants start flowering.

imgrowing · May 6, 2025

no worries about frost, my question was more about if the girls were used to 20 hrs light then went to 15-16 hrs light outside to start flowering, how long should i keep them at 20 hrs to make sure they don't re veg.
weather can turn ugly here mid sept so would like them done then, hence forced flowering asap.

RoadKillSkunkHunt · May 6, 2025

imgrowing said:
no worries about frost, my question was more about if the girls were used to 20 hrs light then went to 15-16 hrs light outside to start flowering, how long should i keep them at 20 hrs to make sure they don't re veg.
weather can turn ugly here mid sept so would like them done then, hence forced flowering asap.

They won't start flowering until the daylength is under 14 hrs. 15-16hrs of light won't trigger flowering.

Frost danger only determines when its safe to put young plants outside. In the fall, your enemy will be dew point. The wet nights of fall cause lots of grows to go sideways at the very end.

imgrowing · May 6, 2025

RoadKillSkunkHunt said:
They won't start flowering until the daylength is under 14 hrs. 15-16hrs of light won't trigger flowering.

Frost danger only determines when its safe to put young plants outside. In the fall, your enemy will be dew point. The wet nights of fall cause lots of grows to go sideways at the very end.

not sure how to word this correctly, what i mean and what i say and type always turn out wrong, but here goes.
lower vancouver island doesn't get 14 hrs or less sunlight until october which would make it impossible to grow photos here.
don't photos sense diminishing hrs of sunlight and start to flower?
hence 20 hrs to 14-15 hrs

RoadKillSkunkHunt · May 6, 2025

imgrowing said:
not sure how to word this correctly, what i mean and what i say and type always turn out wrong, but here goes.
lower vancouver island doesn't get 14 hrs or less sunlight until october which would make it impossible to grow photos here.
don't photos sense diminishing hrs of sunlight and start to flower?
hence 20 hrs to 14-15 hrs

Not like that, no. There's fast-flowering plants but that only moves day length by 15-20 minutes. You still have time to start some autoflowers. Its what will work best outdoors in your area. Some are surprisingly potent.

imgrowing · May 6, 2025

ok all good, but explain to me how people at latitude 48 can possibly grow photos outside then?
here it would take until december to have 14 hrs light or less for 10+ weeks for the girls to ripen.

RoadKillSkunkHunt · May 6, 2025

imgrowing said:
ok all good, but explain to me how people at latitude 48 can possibly grow photos outside then?
here it would take until december to have 14 hrs light or less for 10+ weeks for the girls to ripen.

Light deprivation would be the most likely.

If a grower in your latitude is finishing a photoperiod plant, it was likely bred there to fit the climate. It's what happens in Michigan. Michigan growers also don't run plants that take 10+ weeks of flower to finish either.

imgrowing · Jun 4, 2025

june 4th and i put girls outside.
went from 20 hrs light inside to 15 hrs 56 seconds outside light and decreasing after june 21st.
my thought is that photo period plants sense decreasing hrs of light and switch to flower.
this 12 hour darkness in order to flower to me makes zero sense.
my thought is it takes 2-3 weeks to start transition to flower anyways so that should work good.
may or may not work, i'll let u know.

Grownsince95 · Jun 5, 2025

imgrowing said:
june 4th and i put girls outside.
went from 20 hrs light inside to 15 hrs 56 seconds outside light and decreasing after june 21st.
my thought is that photo period plants sense decreasing hrs of light and switch to flower.
this 12 hour darkness in order to flower to me makes zero sense.
my thought is it takes 2-3 weeks to start transition to flower anyways so that should work good.
may or may not work, i'll let u know.

They'll definitely sense the shorter days but they're not gonna show any pistils until at least the beginning of Sept. If you want them ready before the middle of November you will have to use light depravation techniques.

HerbalEdu · Jun 5, 2025

if you want to flower early a photoperiod outdoor you need a cover to shorten the daylenght.

HerbalEdu · Jun 5, 2025

imgrowing said:
my thought is that photo period plants sense decreasing hrs of light and switch to flower.
this 12 hour darkness in order to flower to me makes zero sense.

they do not sense the lenght of daylight, photoperiods sense the lenght of uninterrupted darkness through pf and pfr receptor

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Eledin · Jun 5, 2025

imgrowing said:
june 4th and i put girls outside.
went from 20 hrs light inside to 15 hrs 56 seconds outside light and decreasing after june 21st.
my thought is that photo period plants sense decreasing hrs of light and switch to flower.
this 12 hour darkness in order to flower to me makes zero sense.
my thought is it takes 2-3 weeks to start transition to flower anyways so that should work good.
may or may not work, i'll let u know.

They can flower with 10 hours of darkness but we indoor growers go directly to 12/12 for flower because its much faster than slowly reducing light hours. Thats one of the reasons why indoors flowering is faster than outdoors. If it made no sense, why would everyone do it?

imgrowing · Jun 5, 2025

HerbalEdu said:
if you want to flower early a photoperiod outdoor you need a cover to shorten the daylenght.

why don't you think 20 hrs light to 16 hrs light isn't shortening daylight hrs?
not trying to be a dick here, but their are several people here that grow photos outside and most of them finish before the rain hits in october, although lots don't.
and nobody has any girls bred for lower vancouver island.

imgrowing · Jun 5, 2025

Eledin said:
They can flower with 10 hours of darkness but we indoor growers go directly to 12/12 for flower because its much faster than slowly reducing light hours. Thats one of the reasons why indoors flowering is faster than outdoors. If it made no sense, why would everyone do it?

what going to 12/12 from 18/6 does is called forced flowering, and your absolutely correct that it's faster.
what i'm trying is forced flowering when going from 20 hrs to 16 and diminishing from there.
it doesn't bother me if it fails, i hope they don't, but i'm trying it at least.
why do i get the feeling that everybody here wants this experiment to fail?

Eledin · Jun 5, 2025

I dont think it will fail at all, slowly reducing the hours is how nature does it and if you do it faster than nature, it will be faster, they wont die or anything I just missread something that you said sorry
"this 12 hour darkness in order to flower to me makes zero sense."
I understand now that you meant that is not necessary for it to be 12 hours for them to flower, not that is a bad idea to do it, sorry.

imgrowing · Jun 5, 2025

also the fact that i mistakenly started 5 photos and 2 autos instead of visa versa kind of made me choose this route.
i only have 1 room.
don't drink and plant people cause it will catch up to you

Eledin · Jun 5, 2025

imgrowing said:
also the fact that i mistakenly started 5 photos and 2 autos instead of visa versa kind of made me choose this route.
i only have 1 room.
don't drink and plant people cause it will catch up to you

Thats the exact same reason I tried 10 hours of darkness in one of my tents too. I was left with more space than I was expecting and it was too late to add more photos so I decided to experiment.

HerbalEdu · Jun 6, 2025

imgrowing said:
why don't you think 20 hrs light to 16 hrs light isn't shortening daylight hrs?
not trying to be a dick here, but their are several people here that grow photos outside and most of them finish before the rain hits in october, although lots don't.
and nobody has any girls bred for lower vancouver island.

seem to me like your messing lot of thing in your head and that your not really understanding how flowering is triggered with photoperiods.

first you need to understand that's not the lenght of daylight plant is sensitive to, but what the plant receptor are measuring is the lenght of uninterupted darkness at night

some strain and some pheno will start to flower with 10h uninterupted darkness some other with 11h, then with 12 hours darkness all strain and pheno will start to flower, then not all strain and not all pheno have the same flowering time, that why not all strain and phenos will start to flower at the same time outdoor and some will finish mid-late september , mid october and some others november.

if you use light deprivation technique outdoor like with a cover (in the morning and/or before dusk), you can have a photoperiod finishing like june, july, or august for exemple

HerbalEdu · Jun 6, 2025

imgrowing said:
what going to 12/12 from 18/6 does is called forced flowering, and your absolutely correct that it's faster.
what i'm trying is forced flowering when going from 20 hrs to 16 and diminishing from there.
it doesn't bother me if it fails, i hope they don't, but i'm trying it at least.
why do i get the feeling that everybody here wants this experiment to fail?

no one want your experiment to fail, but the mechanism behind how flowering is triggered are well known, there actual science behind it.

you can't just stab in the dark with lenght of daylight and hoping that work

imgrowing said:
also the fact that i mistakenly started 5 photos and 2 autos instead of visa versa kind of made me choose this route.
i only have 1 room.
don't drink and plant people cause it will catch up to you

i have had a few time automatics mixed with photoperiods, auto grow just fine under 12/12 what's important at the end of the day is DLI

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going from 20 hrs light to 15ish

going from 20 hrs light to 15ish

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