Your Opinion On 18/6 vs 20/4 vs 24/0?

Vegging Light Cycle Choice


  • Total voters
    78

malicifice

Well-Known Member
The only reason I do 18 on is to save on electricity if I'm vegging with the 400. If I'm using the cfl's they usually stay on 24 hour's because it really doesn't cost anything.
 

tip top toker

Well-Known Member
Recently switched my 18/6 veg to 16/8 to slow it down while I was finishing a flower room if anything they sped up, not slowed down.

My go-forward schedule:
24/0 for clones/seeds - 2-3 weeks depending on growth rate
18/6 for 2-3 weeks
16/8 for 2-4 weeks (depends on how long I want to veg for in that run)
14/10 for 1 week
12/12 for balance until last week
11/13 for last week
36-48 hours of dark, then cut'm down

Don't know if there's any science to it but one of my main drivers is not shocking the plants with any change (light or otherwise), I believe plants need some down time, as a bonus my lights will last longer and save a duple of $ in energy usage.
I don't know if there is any science behind it either, but there is plenty of evidence that shows that there is absolutely no reason not to just go from 18/6etc straight to 12/12 without an issue. Hence why it is the advice always given, it does no harm, and is a one step process. Yours on the other hand sounds like a right ball ache.
 

GroErr

Well-Known Member
I don't know if there is any science behind it either, but there is plenty of evidence that shows that there is absolutely no reason not to just go from 18/6etc straight to 12/12 without an issue. Hence why it is the advice always given, it does no harm, and is a one step process. Yours on the other hand sounds like a right ball ache.
Not really, my timers are so easy to program it's a joke and I'm in there a few times a week so no skin off my back. It goes along with my tendency to not make any changes too quick, regardless of whether it's lights, water, nutes, air, slow and easy, no shocking them in any way. Like I said, it may not be science but I like it so that's all that matters ;)
 

bird mcbride

Well-Known Member
I see there's a poll for this thread. I'd have to say all of the above depending on the application.
Any veg time can go to 12/12 without problem providing the plant is established.
 

racerboy71

bud bootlegger
i'll just say this.. i once read where jorge, i've never grown cannabis in my life, cervantes, said that plants grown under 24 hours of light would grow 33% faster than plants only receiving 18 hours of light per day.. of course, i jumped all over this and tried it out for myself..
well, more results didn't come any where near close to supporting the 33% faster claim made by mr no grow, and in fact, my plants seemed to grow a bit slower under 24 hours of light than they were under only 18.. i don't have any science to back up my claims, just what i had noticed after trying it out for myself.. but my theory is that plants have some functions that they only do under lights out.. plants are living creatures, just like plants, so to me, it makes sense that they'd need a bit of a break like we do at night to recharge their batteries if you will.. i haven't really played around too much with the differences between 20 / 4 and 18/ 6 though, but again, imo, plants do much better when they have at least a few hours of darkness..
 

brimck325

Well-Known Member
i always ran 24/7 but just recently went 15/9 for my outdoor cuts. i actually think they might be growing faster. long as i have a timer, i'll never run 24/7 again...18/6 it will be.
 

Sativied

Well-Known Member
I use 24/0 for seedlings/clones (constant light and temp keeps them very compact) then 18/6 vegging (days rather than weeks) and then 12/12.

There's no benefit into gradually increasing the night time, on the contrary, it only increases the transition period unless you conveniently want to consider those steps down as part of the vegging period. When flipping only the length of the dark period/night matters (to an extend of course) which has to be of a certain length (12hrs will do it for most strains) before it starts to build up and create enough florigen to switch from vegetating to flowering. Days like 14/10 and 16/8 are just wasted time and energy.
 

churchhaze

Well-Known Member
Bullshit!

The sun doesn't shine for 20-24 hours a day. These plants have evolved over eons and if you want the healthiest plants and the fastest growing run 18/6 during veg. Anyone who says otherwise doesn't know what the fuck they're talking about. Any longer than 18 the growth actually slows.
 

tip top toker

Well-Known Member
With regard to growing faster, are people noticing a bushier plant., i.e more nodes, or are they seeing taller plants? i.e stretching more. We all know that a plant in darkness will stretch in search of light, but does this correspond to a 6 hour dark period?
 

Growan

Well-Known Member
Yeah, mor growth or more stretch?
When you switch to 12/12 you get 'stretch '. It's not ever refered to as 'more growth'.
I believe a very wise person considered a comparable occurrence in the legendary 'post #175'.
 

GroErr

Well-Known Member
I haven't noticed any change in the way the plants grow, but haven't really noticed any difference between 20/4, 18/6, or 16/8 for that matter. i think the point is they need some downtime, whether it's 4-6-8 hours I don't think matter all that much, just a matter of preference, convenience or cost. I run them 24/0 early for first couple of weeks then dial them down, as far as 16/8 right now with one veg batch, no noticeable difference one way or another but I'll take the savings, I started going down as far as 16/8 last summer just to deal with the temps and noticed no huge difference one way or another so take them down in steps now, save some $ and get about the same growth rate, nothing wrong with that in my books. What really matters is the stretch, and if anything, doing it in steps to 14/10, then 12/12 I'm seeing more growth in that stage and no real difference in flower development time. Could be strain related, will be able to tell if there's any difference in the next batch, have 4 strains going into the next round.
 

hyroot

Well-Known Member
I do 20/4 for veg. Slightly faster growth with less stretch than 18/6. Plants do need to sleep. They have to go into their phytochrome state . That's nature. Lol. There areas in northern Alaska and Greenland. Where the sun doesn't set for 30-90 days. Then the sun does not come up for the same amount of time.Other areas the sun sets at 11pm. Plants do adapt. They do need sleep as with all species in life. Along the equator. There is more infrared light being dispersed by the sun. So plants flower year round. Like Hawaii... Even in SoCal. There's a small window of veg time late April -early August. The rest of the year is flower time. So saying "nature", has its variables. Recreating nature of strains origins is proper though.
 

tip top toker

Well-Known Member
I do 20/4 for veg. Slightly faster growth with less stretch than 18/6. Plants do need to sleep. They have to go into their phytochrome state . That's nature. Lol. There areas in northern Alaska and Greenland. Where the sun doesn't set for 30-90 days. Then the sun does not come up for the same amount of time.Other areas the sun sets at 11pm. Plants do adapt. They do need sleep as with all species in life. Along the equator. There is more infrared light being dispersed by the sun. So plants flower year round. Like Hawaii... Even in SoCal. There's a small window of veg time late April -early August. The rest of the year is flower time. So saying "nature", has its variables. Recreating nature of strains origins is proper though.
C3 plants don't need a dark period unlike others.
 
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