Lights on/off - temps and humidity

Before you start saying "read previous posts" "do your research" etc etc, i have, but too many conflicting posts and im just looking for simple responses from fellow growers on MY set-up.


Right so this is the deal guys....

Lights on - temps vary between 80-85 and humidity is at 30% (im having issues at the moment which im trying to sort out but i do manually mist the walls of my tent and plants several times a day until i resolve the issue, so the humidity does raise just not consistent)

Lights off - temps vary between 60-70 and humidity is at 55%


Firstly, are the lights on temps ok?!

Secondly, are the lights off temps and humidity ok?!


Im gonna be flowering within the next 3 days and know i will have to slightly lower the humidity nearing the end of flowing.



Im running a 600w hps, 6 x 3gal buckets (soil), 4" double speed extract with filter directly attached, using passive intake via side vents (plenty of fresh air gets in, dont worry) and also run a 6" oscillating fan for air movement.

That sir is a serious fluctuation in temps.
Lights on it should be closer to the 80. I would also try and get those light off temps closer to 70.
30% humidity isn't bad. Think about 50% during flowering works.
Regardless of the setup your still trying to imitate the same conditions as the plants natural habitat.
More importantly your plants will tell you better than anyone on here what they like and don't like.

its a 16 degree drop?! Ive never known that to cause any stress from the many articles ive read. Ive never had a problem before anyway, but you can never say never. I will move the light abit higher, because my thermo is at canopy level so maybe im getting a slightly higher reading then i should be, even though i have my light around a meter away.

My main concern was the humidity issue during the veg stage because once ive switched to 12/12 the lower the humidity the better for resin production and obviously reducing the risk of budrot.

GardenSpecialist said:

its a 16 degree drop?! Ive never known that to cause any stress from the many articles ive read. Ive never had a problem before anyway, but you can never say never. I will move the light abit higher, because my thermo is at canopy level so maybe im getting a slightly higher reading then i should be, even though i have my light around a meter away.

My main concern was the humidity issue during the veg stage because once ive switched to 12/12 the lower the humidity the better for resin production and obviously reducing the risk of budrot.

Click to expand...

A 16 temp drop doesnt matter, if anything it might make your buds turn purple because a 15+ degree temp change at night is usually how that happens. 80-85 is a bit high for the light on though, try to keep that around 76-78.

But as jorge said, listen to your plants first and foremost. If they look happy and healthy, then keep doing what your doing. Remember, its called WEED for a reason, its a weed, it grows through most conditions, but every strain and phenotype is different so it varies.

Thanks for the feedback guys Im gonna have a play around and adjust a few things and see how it goes.

Sounds like your just fine, seems a lot like outdoors conditions during the summer...temps below 55 should be avoided as it will greatly inhibit the uptake of Phosphorus. 30% humidity is not ideal but ok, thats what mine runs in the winter, even lower at times.....

GardenSpecialist said:

Thanks for the feedback guys Im gonna have a play around and adjust a few things and see how it goes.

Click to expand...

Do you have a humidifier in your set up? If not, plug it in to the timer on your light. When the light is on, you will have extra humidity and when it's off, less. Good luck man

Also, if you have a window close by to open it will drop those temps to the low 70's...

No i dont have a humidifier at the moment but im gonna have to invest in one now im thinking. Can a drastic change of humidty when lights off affect anything?! Im hitting like 75% with lights off.

GardenSpecialist said:

No i dont have a humidifier at the moment but im gonna have to invest in one now im thinking. Can a drastic change of humidty when lights off affect anything?! Im hitting like 75% with lights off.

Click to expand...

Yeah man, that probably isn't the best for steady growth. Could it grow in that level of humidity? I'm sure, but it will be very slow growth.

The best range of temp and humidity:
temps 70F-77F
humidity 40-60% during veg
40-45% during bloom
under 40% during drying session

Of course, I am no expert, these are only in my opinion.

If your humidity is low and you dont wanna buy a humidifier, u can raise the humidity by 8-15% by adding a pool of water in ur grow room by ur fan. The water will evaporate over time and raise the humidity by the aforementioned amount.

ive added a bowl of water and to be fair it hasnt done anything but i think thats purely because my grow space is so small, im only using a 1m x 1m tent so it is very confined. Im just spraying the foilage to add some moisture and it seems to be ok at the moment but that could change over night, as you know with the wonderful world of the cannabis plant! lol

Everyone has an opinion. But happy plants are the true test. I do believe 80-85F is too high and that humidity is too high as well. I agree with the previous post in terms of temps and humidity except I always try and keep them lights on between 72-78F (basically the same). I actually drop my temps at night (66-68F lights off) more than some to replicate how they grow naturally with great results.

instead of a bowl put a couple pots filled with water it will help u gotta let some of it evaporate first tho because its not going to be instant