Because the room was getting way to hot with all the lights on and no aircon, I had to switch to external air. I switched two days after I started flowering cycle. Plants are now 5 days into flowering light cycle. Its ebb and flow, rockwool, SOG. I think the temperature switch was pretty extreme. A difference of about 15 degree celsius and co2 difference of 1000ppm.
Pretty much the day after switching to external air some plants are looking really sick and nearly all show more or less sings of the same issue on their leaves. The cubes are still very moist after two days. Normally I had to give them water every day. (Maybe the cubes are still so wet because I dont need to use the dehumidifier with the external air now). On the photo you can see the worst cases. It is like the most weak plants show the worst signs. I need to find out what it is, so I know if it spreads or get worse.
Can you tell me what is that? Is it a fungus, is it some pest or some nutrient problems (maybe some sort of nutrient burn from switching to low metabolism) or maybe it was just to hot before? Maybe the there was too much nutrients pulled in the leaves when it was hot because of high metabolism and when switching temps to cool temperatures this amount is now toxic to the plants.
I need to decide what to do, is it an option to put the plants back into vegetative life cycle until they recovered? Or should I leave them into flowering cycle (already 5 days). I dont want to mess up the yield. What are my options now to still get a good yield? What happens to plants in flower which are stressed, will the flower period be slowed down and prolong or is there a fixed amount of time in flower available and all the time the plant is sick in that time is lost? What happens normally when you transition to flower, are there any visible signs? Because to me it seems these plants are doing nothing now, maybe just regressing and waiting for a pest to come
Also after switching to external air I am already finding small flies in my grow rooms, it also seems something ate some holes in the leaves. Is there some sort of pre filter needed that I need to put on the air intakes or how can I make sure I dont pull in the pests with the air? Is it normal to find insects in the room. Do I need to act already, I dont want to get a pest problem also.
I agree it looks like a ph issue and 15 degrees temp change would change the ph. If the high temp made them happy and the lower temps made them sad, the ph is too low now that its cooler in the room.
If it was me I’d fix the ph issues and give them a week to perk back up at which point I’d remove the damaged leaves and carry on.
How can I fix the ph issues? My ph in the reservoir did not change. My nutrient concentration now is 1500 micro sievert. Just changed the mixture. But the problem occured already before the change and there my nute concentration was lower.
Do you mean I should change back to veg light cycle? Or just wait a week until I cut the leaves?
If it is leaf septoria I would need to cut the infected parts right away?
Reservoir may not have changed but the grow medium sure would have. To fix the problem you have to lower the ph in the res but first take a cup out of the res and drop it’s temp 15 degrees and measure ph to see if that’s whats jamming you up or not. Post the readings here and that will at least give us an idea of where your at. Measure the temp of the grow medium while you’re at it.
Lower temps and less c02 would slow down plant uptake and the issue could be cold wet roots and you may need to water less. Had issues with on when switching to leds where the soil temp was lower due to lack of radiant heat from the hps bulb. I changed the ph lower by .2 on the water/fert end of things and reduced the amount of water given and moved the fan up.
my res temp ist now between 15 and 20 degree celsius. My res is outside of the grow room. You mean I should lower the res temp to 0 - 5 degree celsius?
what about putting plants back to veg, is that an option or not recommended?
If they are under 12-12 now I wouldn’t reveg they’ll be fine once you sort out the issue.
For the love of baby Jesus don’t drop the res to 0-5° C. I just wanted a cup of water from the res lowered to the grow medium temp and checked. If the room temp dropped 15 degrees Celsius whats the temp in the room with the lights on and off. Your night time (lights off) temps must be super low now too.
In my opinion (opinions are like assholes. We all have one) for being such a new grower your attempting to grow in a way that is way to technical without a few normal successful soil/coco grows behind you. You delved into the unknown.
The leaf problems look like massive over fert with ph issues likely adding to it. Your plants are also used to a particular environment with loads of co2 now so they will take a little time to adjust back to looking healthy. I’d feed lite and put them back into 18/6 with plenty of “normal” air circulation and temps kept constant mid 70s. I’d leave the leafs where they are until new growth is prominent. It’ll likely take a week or two for them to adjust and bounce back.
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.
@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.
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.
