Why do my C99 leaves droop every day durring lights ON at the same time?

Sick Plants & Problems
1

I am stumped on this one. This is a C99 grown from a fem seed.

My lights are on an 18/6 schedule. They turn ON at 7AM and off at 1AM. Every evening right about 7PM or so, the leaves on the plant start to droop. By 9PM they are super drooped. They stay that way until some time before lights ON. By 7 AM the next morning, when the lights turn back on, the plant is looking like nothing happened.

This has been going on since I started this grow - about 3 weeks now.

Im growing in a Hi Pressure Aeroponics chamber, and its drain to waste, so the nutes DO NOT circulate. I am running at EC levels between .6 and 1.0. I keep the PH moving between 5.5 and 6.1. I mix up the rez, and set it to a PH of 5.5 to start. By the next day it will be up to 6.2, but the accumulator tank - which feeds the plants - will still be around 5.8 at that point. I then PH back down to the 5.6 range. The tank and rez will now hold that PH pretty well, so I gradually raise the PH over the next several days up to 6.0-6.1. By then its time to top off the rez, so I start over.

Anyway, I have checked PH/EC in all parts of the system, at all different times of the day, and there is no sudden change in the PH/EC at 7PM every day. Once the accumulator tank gets filled, the PH and EC stays very stable.

Humidity in the tent is always around 25%-35% when the lights are ON and goes up to 50%-60% after lights out.

There is nothing else going on that I can find that always happens at that time of evening, and then suddenly changes back some time early in the morning.

The only pattern is that this starts aprox 12 hours after lights ON and stops sometime before lights ON.

Is this just a genetic thing? Anyone else ever see this happening?

Here are some pics.

During the day around 4PM.

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730PM

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11PM

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The next morning at 701AM

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This cycle keeps repeating every single day. I can almost set my watch by the time the leaves start to droop.

Any ideas?

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2

Seen that quite frequently… 1,2/10 plants ive had in the growroom “sleeps” this way…
Ds

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3

I think it’s genetics and the plant seems to be sleeping , either way it’s looking good , if not broken etc …
What breeder is your c99 from - female seeds ?
Iv grown a few of theirs and had no problems ( apart from one kola had a bout of bud-rot at 50 days flo , I’d have let it go for another week/ten days otherwise).
Otherwise yours is healthy mate.
Anyway good luck with her …
Gaz

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4

Is there any change in environment around that time? Following out of curiosity

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5

I believe you are looking at a perfectly normal healthy plant.

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6

Plant looks good to me I agree with the above statements about it wanting to rest , I’v also noticed in one my lastest grow that the some clones I had indoors in the past seemed to give off a blast of terpenens about the same time every evening! Anyone every notice that phenomenon?

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@anon32470837 maybe she should be named
“Old Faithful” ! :stuck_out_tongue_winking_eye::stuck_out_tongue_winking_eye::stuck_out_tongue_winking_eye::stuck_out_tongue_winking_eye:

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8

:bellhop:

It’s saying: “my leaves are stressed every day & by the afternoon/evening i’m worn out but after a good sleep i feel normal again”

My guess is that the low(ish) RH% and leaf temperature are what need examination; with all other factors being optimal, that would be the limiting factor, imo(right?). And there’s that black plastic; Black raises temps 4-7 deg. F. & it could be increasing your air-temp at the micro-local level.

If you have a non-contact/laser thermometer I’d check leaf temps & plot them along the photo time-line… or just raise the lights, change the air-circulation & start misting.

:blush:

:evergreen_tree:

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9

My white widow autos did that all through veg on 18/6 - droopy by end of day. Budding out just fine. I think @cannabissequoia is right on point - simply tired - leaves may be using more water than transport can provide. During the dark transpiration and everything else slows down, and they perk up again.

Since cannabis doesn’t mind getting a little dry, I wouldnt worry about it and stay the course
:+1:

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…Also what about the temperature of the solution/res.? that might be getting hot by the end of the work day :sweat_smile:

:evergreen_tree:

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11

This seems natural to me, some strains just do that almost as if they are programmed for a rest. Transpiration plays a role of course.

I’ve been recommended silica as a way to keep plants praying for longer periods of time, but I’m of the belief that if they want a break let em have it.

Edit: At first I thought you were saying leaves DROPPED at the same time daily. Now that would have been a head scratcher!

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12

All my outdoor plants drooped at night and perked back up in the morning. Never considered it a problem. I just figured they were doing their thing. Lol

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14

Im no expert but they seems to be sleep to me

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15

Very interesting! Im glad to hear this is not uncommon.

The resting after a stressful day seems to fit the situation pretty well I think. I know the tent temps are on the high side. They are staying in the low 80’s and I prefer the high 70’s. RH is really low too, but not much I can do about that.

Rez temps are not a factor. The rez stays at room temp - which is in the 60 always this time of year. The root chamber also stays in the hi 60’s.

Im going to see if I can get the tent temps down and see if that changes anything.

Thanks for the replies

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16

@Tinytuttle Yes! One of my plants will get a very strong green/chlorophyll odor literally right when the lights go out when it’s in veg. It’s crazy strong! Not even 25% of that odor is present when the lights are on. It’s an interesting trait that I would like to know more about.

And to add to the thread… Yeah this is pretty common amongst many strains and indoor lighting from my experience. I have a few that droop at least 3 hours before the lights go off like clockwork. 18 hours of nonstop intense light is not really normal in nature, so this seems to be their response to having collected sufficient energy for the processes it carries on through the dark cycle. Really nothing to be alarmed with and in some cases/strains it can actually let light in to the lower half of the plant and kinda work in your favor. Cheers my man!

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17

To test the stress theory, I have been trying to keep the tent temps lower the last two days. Its hard to tell for sure, but there may be a slight improvement - or maybe not. I have only been able to drop the temps about 2 deg F, so not much cooler.

I need to re-work my ventilation setup to get more fresh (cool) air.

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18

IMO is the lack of moisture and maybe a just a bit short of N, try this and see if the leaves still doing that, find a transparent bucket, or otherwise cover the plant with some clean film allowing couple of cm between the plant and the film itself.
At the same time spray the plant with an highly nitrogen fertiliser.
i would like to say that the same day you will see some changes in those leaves. If not allow one day more and if still no changes, it’s genetics, but please have a try

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19

Interesting thought. I have a DIY humidity dome I can try out. I’ll let you know.

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Over the last few days, I managed to lower the temps in the tent but not much. It went from an average of 26-27 C lights on to 24-25 C lights ON. That seemed to help to a small degree. The wilting started a little later and wasnt quite as severe - but not a lot of improvement.

So, starting last night I added a humidity dome and put some glasses of water inside it. The average humidity went from the 27% to 30% range up to 35-39%.

That seems to also have helped even more. Tonight there is still wilting going on, but its not as bad, and it seems to have started later in the evening. Its now 11:30 PM and it looks like it usually does at around 8:30 PM.

Im not sure how Im going to get the humidity any higher unless I build a serious humidifier.

So, this seems to be at least partly due to stress - mainly low humidity. Since I have nit seen this in any of the plants in my earlier grows, Im thinking that its also at least partly genetics in the form of less tolerance for low humidity. All my other grows were in the same tent with the same lights and the same humidity ranges.

I will up-date again in another few days and let you know how it is going. This was a good learning experience.

Thanks to all who contributed!!!

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21

Happy to read that is working, there’s a quite simple way, for free, and so healthy, add more plants in that cabinet, they doesn’t have to be cannabis, any basil, parsley, tomatoes, chilli will do, the more plants you have got the higher humidity you will have on your environment, and also a fresh supply of herbs :blush:.

Simple right?

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