Can INCREASING light hours confuse seedlings to early flower??

brown_thumb · Jun 10, 2018

I have five plants which I began supplementing with artificial light (extending light hours) when they were only 25-50mm tall. They're now 75-150mm tall (after considering I added more soil).

The seedlings were started under 13/11 hours of natural light, though they're in my back yard and much of that time is in bright open shade. I wanted to ensure they stay in veg and grow as much as possible so I began moving them into a light box after the natural light turns to afternoon shade. I started this about three weeks ago and they seemed to love the extra hours of light. It seems they grew faster under LED light than in natural sunlight.

I've always had problems with early flowering. I just can't understand how INCREASING light hours can cause plants to go into early flower.

I'm so pissed, depressed and confused, I'm at my wit's limit.

PLEASE HELP!!!

WelderDan · Jun 10, 2018

How long were they under 13/11 before you started supplemental lighting? Most hybrids will begin flowering under that schedule.

You likely triggered flowering before beginning supplemental lighting. They will eventually revert back to a vegetative state if you keep them at something like 18/6.

Increasing light hours won't trigger flowering, but you do have to start them under longer light hours to keep them from flowering early.

MJPassion · Jun 10, 2018

It’s not the increasing hours,
It’s the general lack of light that triggers flower.
Do a little looking about the web concerning phytochrome & how it works in plants.

brown_thumb · Jun 10, 2018

WelderDan said:
How long were they under 13/11 before you started supplemental lighting? Most hybrids will begin flowering under that schedule.

You likely triggered flowering before beginning supplemental lighting. They will eventually revert back to a vegetative state if you keep them at something like 18/6.

Increasing light hours won't trigger flowering, but you do have to start them under longer light hours to keep them from flowering early.

The seeds were popped in mid April and they were always under natural daylight. The total daylight hours here in mid April is 13+ but again, much of the light in my back yard is in bright open shade.

I began moving the plants into the light box to extend light hours about three weeks ago, so the change was made when the plants were about 3-4 weeks old.

The flowers only began to show (barely) about three days ago.

brown_thumb · Jun 10, 2018

MJPassion said:
It’s not the increasing hours,
It’s the general lack of light that triggers flower.
Do a little looking about the web concerning phytochrome & how it works in plants.

I've begun to study how light wavelength affects circadian behavior and it seems to be as important as the hours of light. Red and far-red light seems to be as strong a signal as hours of light, perhaps more so.

This might be the problem. I have three colors of LED lights (5K, 6K, 2.7K) in the light box in addition to a few incandescent bulbs. I thought a mix of wavelengths would be best to offer the plants the widest spectrum of wavelengths I can afford to give them. This might be my error.

It might work better if I used 6K LED's for most of the time in the box, plus incandescent bulbs timed to light 30-60 minutes before and after the LED's are active. This plus avoiding early morning and late evening outside light might solve the problem. I don't know.

burmese · Jun 10, 2018

they must be stunted for nearly 2months plants so small and if not with bad light condition then bad earth reaction.
And these ,,border conditions,,can trigger plant to only survive // so flower?// but they will outgrow from it if you say they are better now

WelderDan · Jun 10, 2018

brown_thumb said:
I've begun to study how light wavelength affects circadian behavior and it seems to be as important as the hours of light. Red and far-red light seems to be as strong a signal as hours of light, perhaps more so.

This might be the problem. I have three colors of LED lights (5K, 6K, 2.7K) in the light box in addition to a few incandescent bulbs. I thought a mix of wavelengths would be best to offer the plants the widest spectrum of wavelengths I can afford to give them. This might be my error.

It might work better if I used 6K LED's for most of the time in the box, plus incandescent bulbs timed to light 30-60 minutes before and after the LED's are active. This plus avoiding early morning and late evening outside light might solve the problem. I don't know.

You are overthinking this. Most hybrids will start to flower at about 10 hours of darkness. You want to start the plants at no more than 6 hours of darkness to maintain a persistent vegetative state.

I've always used 24/0. Some people swear by 18/6 because they feel the plant needs a rest period. Either way, 24/0 or 18/6 will keep a plant in a vegetative state indefinitely. There are exceptions, like with Sweet Pink Grapefruit, where it will start flowering when it gets rootbound, regardless of light schedule.

The bottom line is that you gave them enough dark hours to trigger flowering.

brown_thumb · Jun 10, 2018

Well... shit. I think I need to give up trying to grow outdoors and build a grow room. It seems I can't depend on Mother Nature to cooperate with me. I guess I need more consistent control over all conditions than Mother Nature can offer.

WelderDan · Jun 10, 2018

brown_thumb said:
Well... shit. I think I need to give up trying to grow outdoors and build a grow room. It seems I can't depend on Mother Nature to cooperate with me. I guess I need more consistent control over all conditions than Mother Nature can offer.

Or pick a strain more suited to your environment. Maintaining a consistent environment indoors has its own challenges.

Don't get discouraged with outdoors. Start your plants indoors under controlled conditions and then move them outdoors to finish.

Cannabis is not hard to grow. The problem is wading through all the bullshit information floating around. Once you know what it needs, and just as important, what it doesn't need, you'll be fine.

Simple is better, especially when you are just learning. Once you understand the basics, then you can experiment.

sdd420 · Jun 10, 2018

If you put the plant outside before the solstice it senses each day is longer and does not flower. After the solstice the days decrease and the plant will flower without supplemental lighting . I’m flowering plants inside now that I will put outside to finish flowering after 6/21. Peace sdd

brown_thumb · Jun 11, 2018

I planted as the days were growing longer. I was going to stop the extra lighting in July or August after they were larger.

rexamus616 · Jun 11, 2018

hey mate. Don't despair, just learn from your experiences... no one here has conditions exactly like yours....

just because the days are technically 'getting longer' doesn't mean the plants are getting the exact amount of daylight hours that is calculated for your area.... Theres always trees, mountains, fences, houses etc. that cut it back a bit....

I used to get upset when i'd done all the preparation for a big plant for the season, only to have the cutting/seed plant flower early, limiting overall yield and setting me back a few weeks of growth etc. etc....

Nowdays i've learnt that only the late-flowering sativas will grow without early flowering, and i've found i can also get a spring summer early crop of any indica varieties (meaning i have some nice fresh bud in the 'dry' season - when everyone has no weed in my area!)

I've found that certain varieties (more indica dominant) will flower unless planted later in spring... (which is in november in my hemisphere, or may in your hemisphere)

squeeze them lemons and make some lemonade man~!

Theres always next season! :tiphat:

brown_thumb · Jun 11, 2018

rexamus616 said:
hey mate. Don't despair, just learn from your experiences... no one here has conditions exactly like yours....

just because the days are technically 'getting longer' doesn't mean the plants are getting the exact amount of daylight hours that is calculated for your area.... Theres always trees, mountains, fences, houses etc. that cut it back a bit....

I used to get upset when i'd done all the preparation for a big plant for the season, only to have the cutting/seed plant flower early, limiting overall yield and setting me back a few weeks of growth etc. etc....

Nowdays i've learnt that only the late-flowering sativas will grow without early flowering, and i've found i can also get a spring summer early crop of any indica varieties (meaning i have some nice fresh bud in the 'dry' season - when everyone has no weed in my area!)

I've found that certain varieties (more indica dominant) will flower unless planted later in spring... (which is in november in my hemisphere, or may in your hemisphere)

squeeze them lemons and make some lemonade man~!

Theres always next season!

Thank you. Are you saying that bright open shade in daylight hours (but out of direct sunlight) affects circadian rhythm? If so then that's definitely my problem. My back yard is small and the fence shades the plants during morning and evening hours.

MJPassion · Jun 11, 2018

brown_thumb said:
Thank you. Are you saying that bright open shade in daylight hours (but out of direct sunlight) affects circadian rhythm? If so then that's definitely my problem. My back yard is small and the fence shades the plants during morning and evening hours.

Shade absolutely affects the flower cycle.
My plants are beginning to flower a bit also. They’re shaded from 10ish(am) to about 3 to 4(pm). Well... dappled sunlight coming through a 30 ft elm tree anyway. I’m at a new location & recently transplanted as well so hoping things go back to veg for a few more weeks.

brown_thumb · Jun 11, 2018

^^^ Well... I'll be gall-darned!!!!!

Now I know why I can't control my girls' flowering. Now I know to move them into the lightbox during all times they'll be in shade outside. This is okay for just a few plants but a bit more challenging as they grow.

I really do need to build a grow room!!

rexamus616 · Jun 11, 2018

you can just make a little veg room / mother cupboard to get seed starts or cuttings growing abit during those shorter days....

is cheaper and easier than running a big tent with HPS or whatever....

I just have a small cupboard with some fluoros which does alright.... cheap to run, only need a tiny quiet fan etc.

Shady ambient light isn't strong enuf to stop plants flowering.... i learnt that the hard way trying to grow in the forest.... live and learn i spose

*edit:

You how increasing light hours CAN affect seed starts, is by stressing them... turning them hermi etc.

brown_thumb · Jun 11, 2018

^^^ Wow... more confirmation that bright open shade isn't enough light to stop flowering.

Thank you all for this info. I learned something VERY useful today!!

insomniac_AU · Jun 11, 2018

rexamus616 said:
you can just make a little veg room / mother cupboard to get seed starts or cuttings growing abit during those shorter days....

is cheaper and easier than running a big tent with HPS or whatever....

I just have a small cupboard with some fluoros which does alright.... cheap to run, only need a tiny quiet fan etc.

Shady ambient light isn't strong enuf to stop plants flowering.... i learnt that the hard way trying to grow in the forest.... live and learn i spose

*edit:

You how increasing light hours CAN affect seed starts, is by stressing them... turning them hermi etc.

That's what I would do. My veg room just has 2 80W 6500k CFLs.
These are my girls that will be going in later in the week.

You could grow them as large as you like under 18/6 and they'll never flower until you put them outside.

Satyros · Jun 11, 2018

brown_thumb said:
I've begun to study how light wavelength affects circadian behavior and it seems to be as important as the hours of light. Red and far-red light seems to be as strong a signal as hours of light, perhaps more so.

Yes, the reds are a signal that autumn is coming. Dominate with blue for veg.

rexamus616 · Jun 11, 2018

insomniac_AU said:
That's what I would do. My veg room just has 2 80W 6500k CFLs.
These are my girls that will be going in later in the week.
[URL=https://www.icmag.com/ic/picture.php?albumid=77292&pictureid=1858076&thumb=1]View Image[/URL] [URL=https://www.icmag.com/ic/picture.php?albumid=77292&pictureid=1858077&thumb=1]View Image[/URL]
You could grow them as large as you like under 18/6 and they'll never flower until you put them outside.

Thats exactly what i've got in my cupboard!

And brown_thumb if you can, get a light meter to test the light intensity.

Good luck mate

Can INCREASING light hours confuse seedlings to early flower??

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