18 hours too much light for my plants?

[Nate_in_AK]

Lights on @ 0600, off @ 0000.

I noticed the last 2 days that the plants seem droop a bit after 2100-2200. In the morning they have looked fine again. (NOT running out of water)

Is this a sign that I should reduce the light schedule to 16/8 perhaps?

 

[detroitjoe]

Plants "droop" for a number of reasons.
if you notice, they will droop in the dark When the lights go out. Thats completely normal and healthy.
Put your hand under the droopiness and push up. do the leaves have strength or do they flop around?

 

[freezeland2]

Lights on @ 0600, off @ 0000.

I noticed the last 2 days that the plants seem droop a bit after 2100-2200. In the morning they have looked fine again. (NOT running out of water)

Is this a sign that I should reduce the light schedule to 16/8 perhaps?

It’s normal. They know it’s getting close to their rest time. Seriously, they know.

 

[Budtown]

Yeah plants always look abit sad before lights off

 

[growsince79]

Lights on @ 0600, off @ 0000.

I noticed the last 2 days that the plants seem droop a bit after 2100-2200. In the morning they have looked fine again. (NOT running out of water)

Is this a sign that I should reduce the light schedule to 16/8 perhaps?

yes

 

[Nate_in_AK]

yes

I changed my light timer to 16/8, if they die I'm blaming you.

 

[detroitjoe]

It’s normal. They know it’s getting close to their rest time. Seriously, they know.

plants dont "rest"
ive never in my life heard of marijuana plants "resting"

can you be more specific

 

[MilkyTrichomes]

I don’t know that plants can tell time, I think they have received all the light they can take for the day (DLI).

 

[detroitjoe]

I don’t know that plants can tell time, I think they have received all the light they can take for the day (DLI).

lol ya might want to get them a rolex! lol

Its like this:
longer light periods means that the plant will continue to drink and feed.
if you dont keep up with the needs , then you get problems.

ie: you cant keep working out to build muscle if your not eating right. if you keep working out, then you need to keep eating.

one system piggybacks off the other.

 

[Nate_in_AK]

longer light periods means that the plant will continue to drink and feed.
if you dont keep up with the needs , then you get problems.

I strongly suspect this is not entirely true. If so we would just run lights 24/7 during veg.

 

[growsince79]

I strongly suspect this is not entirely true. If so we would just run lights 24/7 during veg.

You can grow with bright light and max the dli at 16hrs. Same brightness at 24hrs and the plant will suffer. Roots and soil need time to recharge ime.

 

[ComfortablyNumb]

I strongly suspect this is not entirely true. If so we would just run lights 24/7 during veg.

You can. Autos are often run 24 hrs for their entire life to help get bigger buds.
The change to less light is to mimic the seasons. It helps the plant change modes from veg to bloom.
Since autos have their own schedule, you do not need to change the light cycle.

 

[Nate_in_AK]

You can grow with bright light and max the dli at 16hrs. Same brightness at 24hrs and the plant will suffer. Roots and soil need time to recharge ime.

Off to read about DLI. The immediate question this raises: Does it make a difference to the plant if I turn the light intensity down or shorten the lights-on duration?

 

[growsince79]

You can. Autos are often run 24 hrs for their entire life to help get bigger buds.
The change to less light is to mimic the seasons. It helps the plant change modes from veg to bloom.
Since autos have their own schedule, you do not need to change the light cycle.

I don't do autos. I do know my photos grow stronger stalk and shorter internodes with 16hrs vs 18hrs. I think the roots need dark even during veg. Even most auto growers I follow don't do 24.

 

[detroitjoe]

I strongly suspect this is not entirely true. If so we would just run lights 24/7 during veg.

I hate to be the one to hurt your feelings & you can strongly suspect, and object all you want

A 'normal" marijuana plant ( normal meaning NOT autoflower ) can and will enjoy 24 hours of light during VEG

It doesnt matter what type of system you are using.
Metal Halide / Fluros - the more the light is on, the more the plant will keep in the veg stage
HPS - can be used to veg but is mainly a flowering spectrum. I veg with hps,MH and fluros.
LEDs- Same shit. you can run them 24 7 and the plant will keep vegging.

As long as the main lights have the correct spectrum for vegging, you can veg her 24 hours aday.

Im not being cocky or arrogant but it seems your not here to learn.







The plant does NOT have to "sleep/rest"

 

[Nate_in_AK]

Im not being cocky or arrogant but it seems your not here to learn.

Kind of coming across that way, my dude.

Do you have anything to offer (links to studies or anything) outside of your own personal experience? I'm searching Google for DLI articles, and so far what I'm finding supports @growsince79 's advice.

 

[Nate_in_AK]

What I'm finding so far via Google:

My light: ViparSpectra P2000, manufacturer reports: 1087 umol/s/m2 @ 18" above canopy.

With an 18 hour light schedule, this equates to DLI of approx. 70 - https://www.waveformlighting.com/horticulture/daily-light-integral-dli-calculator

Marijuana usually requires a daily light integral of around 40 to 51 units to grow as expected. Other factors determine how much light levels cannabis can tolerate. Some reports show marijuana could tolerate much higher daily light integral. -- https://www.420greenthumb.com/how-much-daily-light-integral-dli-does-cannabis-require/

I'll happily stipulate that there is room for error here, but the math appears to match the results.

I can reduce the photoperiod, raise the light, or reduce the intensity. What I'm reading so far suggests keeping the light intensity high and reducing the photoperiod. For now I'm sticking with 16/8.

 

[detroitjoe]

Kind of coming across that way, my dude.

Do you have anything to offer (links to studies or anything) outside of your own personal experience? I'm searching Google for DLI articles, and so far what I'm finding supports @growsince79 's advice.

Im not your dude and Im not into males referring to me as "their" dude either . I dont care if its trendy lingo.
My name isnt spicoli from fast times

Do you have anything to offer (links to studies or anything) outside of your own personal experience? I'm searching Google for DLI articles, and so far what I'm finding supports @growsince79 's advice.

I have over 35+ years cultivating & breeding and enough notes to fill a storage unit for a 4 bedroom house. 99.9% of said notes have nothing to do with the internet.
I have hundreds of hard drives with studies from various scientists and institutions.
Why on earth would I just hand over my lifes work to a nobody? and dont take it personal because i wrote that your a nobody because it is the truth. You have no bearing on my life other than me exercising my keyboard speed.
Why? you dont deserve my knowledge nor do I care who is "right" and who is "wrong"
Text book is different than the real world. It always is.

 

[Aqua Man]

Ok plants don't rest I agree. They change processes during lights on and off. Both are crucial imo.

They absolutely do get used to a light cycle and will start to droop a bit as they slow transpiration rates in anticipation of a dark cycle. They will also do then when they can no longer keep up the rates of photosynthesis and transition more towards photorespiration if under very high light.

This usually starts about an hour or touch longer before lights out.

 

[freezeland2]

plants dont "rest"
ive never in my life heard of marijuana plants "resting"

can you be more specific

Like they don’t need more light. It’s why they droop prior to sunset or just before lights off. I was being very simplistic to the OP.