Do plants need a cool Cycle?

[Techead]

Well, with all the heat we've been having, I altered my lights so they were on at night to keep the girls cosy, but a nagging thought occurred to me!
Day time temps with the lights off, we are talking air temps here have been hitting 30<36 degrees C in the shed where I grow.
With the lights on and the fans flat out, it's roughly the same, so the LED's don't make that much difference, actually the fans drop the 'apparent' temps in the tanks to a couple of degrees lower than ambient as the inlets are on the floor.
So I assumed they would be better in the day with the lights off, at night with the cooler air, the tanks are running at 28c approx., so I figure the lights actuall warm the air inside the tank quite a bit BUT, note the big BUT, do they actually need a cooler cycle to thrive.
Basically mine are getting 28c at night under lights and were getting 28<30c during the day with the lights off.
Obviously, I havn't experienced these unique high temps throughout the light and dark cycle, a few of the latest don't look overly healthy, they are still early days i.e 4 weeks old, so may catch up, but my question is, do they need a cooler environment during their dark time, I suspect they do like they get in a natural cycle.
I may switch the lights back on during the daytime as the fans keep the temps equal or slightly lower that the ambient temp, I figure they are getting there anyway without lights, so why bother, it doesn't seem to change a thing, BTW each grow tank has three internal fans wired in series, so they run slower but shift about the same amount of air but are incredibly quiet due to the low speed, I picked up 15 Mains powered induction motors at a Scrapyard for £15. They are quite small, about 3" in dia, run on their own they consume 8w, three in series consume about the same. The fans actual price is £26 EACH, these are fitted with bearings, so are a really good make, they were still in the box and there were hundreds of them there!
Obviously not a problem now as the air temp in the shed is just 17c, well it is Pi**ing down at the moment but perplexing all the same?

[GEORGE]

Well, with all the heat we've been having, I altered my lights so they were on at night to keep the girls cosy, but a nagging thought occurred to me!
Day time temps with the lights off, we are talking air temps here have been hitting 30<36 degrees C in the shed where I grow.
With the lights on and the fans flat out, it's roughly the same, so the LED's don't make that much difference, actually the fans drop the 'apparent' temps in the tanks to a couple of degrees lower than ambient as the inlets are on the floor.
So I assumed they would be better in the day with the lights off, at night with the cooler air, the tanks are running at 28c approx., so I figure the lights actuall warm the air inside the tank quite a bit BUT, note the big BUT, do they actually need a cooler cycle to thrive.
Basically mine are getting 28c at night under lights and were getting 28<30c during the day with the lights off.
Obviously, I havn't experienced these unique high temps throughout the light and dark cycle, a few of the latest don't look overly healthy, they are still early days i.e 4 weeks old, so may catch up, but my question is, do they need a cooler environment during their dark time, I suspect they do like they get in a natural cycle.
I may switch the lights back on during the daytime as the fans keep the temps equal or slightly lower that the ambient temp, I figure they are getting there anyway without lights, so why bother, it doesn't seem to change a thing, BTW each grow tank has three internal fans wired in series, so they run slower but shift about the same amount of air but are incredibly quiet due to the low speed, I picked up 15 Mains powered induction motors at a Scrapyard for £15. They are quite small, about 3" in dia, run on their own they consume 8w, three in series consume about the same. The fans actual price is £26 EACH, these are fitted with bearings, so are a really good make, they were still in the box and there were hundreds of them there!
Obviously not a problem now as the air temp in the shed is just 17c, well it is Pi**ing down at the moment but perplexing all the same?

From what I read, they thrive with 5 degrees different with lights off. Most best temps would be 77 degrees lights on, and 72 lights off. So, you a little like me, mine run 31 lights on, but seem to be doing ok.

[Techead]

Just thought I'd update this and pose a further question, my girls had thirty six hours of Dark time but refused to flower on 12/12, now I altered the lights, they get cooler air at night. Straight away they both went into flower. If I had thought or had a bigger grow area, I would have split them up and seen if a slight 'Chill' made any difference.
We probably won't have weather like this again, i.e. Heatwave, BUT if I get another that 'appears' stuck in Veg, it's getting an 'Arctic' blast!
I might try this on one two 'Girls' in the future though, if the one I 'Chill' Flowers first I will be very surprised! has anybody else tried this, Techead

[GEORGE]

Just thought I'd update this and pose a further question, my girls had thirty six hours of Dark time but refused to flower on 12/12, now I altered the lights, they get cooler air at night. Straight away they both went into flower. If I had thought or had a bigger grow area, I would have split them up and seen if a slight 'Chill' made any difference.
We probably won't have weather like this again, i.e. Heatwave, BUT if I get another that 'appears' stuck in Veg, it's getting an 'Arctic' blast!
I might try this on one two 'Girls' in the future though, if the one I 'Chill' Flowers first I will be very surprised! has anybody else tried this, Techead

12-12 cycle is the only way you will flower a Photo. A cold blast will just upset the plant. Some photo's take as long as 15, 16 days of 12-12 to start to flower.