20° C is the minimum temperature I would run a lights out. You want the temp to be closer to 25° C lights on. And if you are running CO2, you could easily go up to 30° C. No wonder your plants reacted the way they did.
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@ReikoX But you don’t think that plants should be able to grow with lower temps than 20 degree celcius without problems? Of course it would be something different if you just switch from one day to another to much lower temperature than the plant is used.
@50State @Esrgood4u The plants are shocked still, not much happening. I will try to flush the cubes, because I think the ph is off in the cubes after the drastic temperature change.
- I still not decided if I should reveg or not. I did read if I reveg and then revert to flower again I will get hermies and strange leaf growth, also it would take time until they switch back again. Also I worry the plants will get too big.
- I need to know if the flower cycle be lenghtened by that time they are now in shock shocked or if that is lost time and the flowering period is fixed?
20° C is about 68°F, at this temperature the plants metabolism is reduced. The plant can no longer feed at that temperature. It’s too cold, that’s my diagnosis. Do what you will with that info.
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I did read the plant goes dormant at around 50 °F ???
Pls have a look at the informations that I have
source is https://fluence.science/wp-content/uploads/2016/09/High-PPFD-Cultivation-Guide-9.27.16.pdf
Both those graphs support what I am saying. Both of them show a significant increase in photosynthesis at 84°F compared to 68°F.
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of course. But I never said I have 68°F with CO2. I have it now without CO2. And in the graph it shows not much a difference to the optimum temperature (without CO2). It needs to go lower than 68°F to have a big difference (without CO2).
But as said before, yes its clear, such a drastic change like with my plants is not good.
If cant raise heat try to lower humidity to stabilize the vpd in your room or tent
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ok, I reverted my plants from early flower back to veg again. Most plants created lots of foliage in the meantime, although some plants didn’t make it. The best growing and robust plants, I preserved and I took clones for the next grow already. I did prune my plants foliage a lot. I only left the upper third part of foliage of the plants. I am going to switch them now back to flower.
What worries me a bit is that some leaves still showed some yellowing. Is it normal that when the plants grow bigger that a part of the leaves start to yellow?
But something that concerns me more is that I have a bunch of plants which have stems which are not very strong. If I touch them the plants stem start to limp and sometimes I can rip of green leaves very easily.
I took many clones also. And it seems that the stem of some of the clones quickly collapsed at the point of the stem where it comes out of the medium, which made the clone die?
Is there a special nutrient which is responsible for such sort or weakness?
I am not sure what is the reason of the problem. The nutrient solution seems good ppt and ph wise…
Or is it maybe a fungus which still causes some leaves yellowing? Yesterday I sprayed a fungicide…
Ok plants are now in 3 weeks bloom.
But still with some plants the issue seems to be around. Look at the leaves. The older the leaves and the smaller the plant, the more it is visible. It starts at the tips and finally the leaf will die. What is that??? Could it be that some iron is leeching in my nutes? Or is it normal that the old leaves die like that???
On the last picture is there also some light bleaching?
Btw I have to adjust ph of the reservoir every day before flooding. I adjust it to 5.8.
Heat stress… I run Co2 in the winter. I know what happens in the summer time … Yikes! … Good decision to switch to external air. 
Good luck to ya.
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Tell me how does it look the heat stress? In the summertime? Is it comparable?
I have now 30 degreee celsius in the room. But I have no co2.
My many motherplants which are in veg, doesn’t show these symptoms.
Only some blooming plants show deficencies.
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pH or nutrient built up issue
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You should have a healthy pH swing to allow the plant absorb all the nutrients it needs. Look at this chart, notice the range for hydroponics on the left is 5.5 - 6.1. So you’re locking out P and Mg.
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That means I let the ph go until 6.1, and then lower it again and then repeat?
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Yep, that’s the idea.
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Am I correct and the potassium range for hydro is entirely different in that post?
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It is indeed different. I have a couple more, although no providence with any. The bottom one does not say if it is for soil or hydro for example. I think I will do some research and find something with a citation or reference. The advice is still good though, if you drift from 5.5 - 6.1 then repeat you should avoid deficiencies.
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ok I changed the nutients completely. After I put in the nutrients in the RO water, it has a ph of 5.3. Where should I put the ph now considering the actual state of my plants? 5.5 or maybe 6.1 (Later start low of course again)?
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I like to shoot for between 5.6-5.8 when I make a fresh resivoir.
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Hate to say it, But I think you may have bitten off more than you can chew…
Learn the fundamentals first before starting up an ebb and flow grow, especially with co2 supplementation… If anything, I would of done a dwc setup instead.
It takes alot of time, money, and patience dialing things in when ya start messing around with Co2…
Grab a bucket if you wanna continue growing hydroponically, and open up a window.
I wish you and yours only the best. Not trying to beat you down in any way my friend. Good luck
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