Temperature swing during flowering

Hey all,

I just put my girls in to 12/12. With the lights on the temperature is around 78 to 80 degrees. With the lights off, it drops to around 55 degrees after a couple hours. This is because I continue to pump fresh air from outside my house in to my flower room at all times. Is this too large of a temp difference? I figure it should be ok, since the same is seen out in nature, but wanted to ask. I hope to hear from some of you. Thanks.

-Snut

From the growfaq:


A humidity and temperature gauge are essential in any growroom. Daytime conditions should be 70-80 degrees without co2, 80-90 degrees with co2 until the last two weeks when daytime temps should be kept between 70-80 and co2 can be reduced to adjust for the lower metabolism. Night temperatures should be kept above 60 degrees to prevent stress. It is preferable during flowering to have a night temperature drop of 10-20 degrees to stimulate flowering hormones and reduce stem elongation.



So,I'd say get em above 60 at night and you're pretty golden. I don't know if five degrees will make a big difference,but better safe than sorry.

55 f is when photosynthesis stops, so you have to keep it above 55f you should probably get a little heater fan or something to help that....it will slow the growth of your plants massively, a 30f drop is too much. my temps are 76 to 80 in the day and 65-70 in the off hours.

Thats about what my room gets down to 62-64. I would think they should be fine. I would say with those temps, growing a purple strain would make the 'purple' really stand out. Ur fine. Good luck...

even in nature you have warm days and cool nights

I think what I'll do is just stick a timer on my ventilation fan and have it turn off when the plants are in darkness. I had it pulling in fresh air 24 hours a day while my lights where running during vegetation...

My girls light's just turned off an hour ago, so I'm gonna go shut off the intake fan and see what my temps get down to today. I'm pretty sure that this will take care of it. Thanks for the help so far everyone.

-Snut

Remember, don't be opening the door during the night cycle and letting light in.Then you're going to run the risk of hermies.

snutter said:

I think what I'll do is just stick a timer on my ventilation fan and have it turn off when the plants are in darkness. I had it pulling in fresh air 24 hours a day while my lights where running during vegetation...

My girls light's just turned off an hour ago, so I'm gonna go shut off the intake fan and see what my temps get down to today. I'm pretty sure that this will take care of it. Thanks for the help so far everyone.

-Snut

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jordisgarden said:

55 f is when photosynthesis stops, so you have to keep it above 55f you should probably get a little heater fan or something to help that....it will slow the growth of your plants massively, a 30f drop is too much. my temps are 76 to 80 in the day and 65-70 in the off hours.

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This is an odd response. How does photosynthesis continue in the dark??? I don't understand....

Stoney McFried said:

Remember, don't be opening the door during the night cycle and letting light in.Then you're going to run the risk of hermies.

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Yes, of course... Always a good reminder. The intake fan's power outlet is outside of my grow room, so no worries about light getting to them. I'd never go in to my grow room during the dark cycle unless it was a matter of life and death.

I've heard that you can use green or red lights and they won't effect the plant. Does anyone know if this is true???

-Snut

snutter said:

This is an odd response. How does photosynthesis continue in the dark??? I don't understand....

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i didnt mean photosynthesis . thats the reaction with sun right? i just meant that the plant would stop growing at below 55 f . sorry my bad

snutter said:

Yes, of course... Always a good reminder. The intake fan's power outlet is outside of my grow room, so no worries about light getting to them. I'd never go in to my grow room during the dark cycle unless it was a matter of life and death.

I've heard that you can use green or red lights and they won't effect the plant. Does anyone know if this is true???

-Snut

Click to expand...

ive been into my grow many many times. ive turned on the lights in the middle for 5 minutes many times. i never had hermies or any issues. i know i shouldnt but ive always gone in in the dark. no probs. the only time i ever grew hermied plants is when i trusted a friend who told me the seeds he was giving me were good. i knew better but i still did it for him and they hermied.

Night temperatures should be kept above 60 degrees to prevent stress. It is preferable during flowering to have a night temperature drop of 10-20 degrees to stimulate flowering hormones and reduce stem elongation.


hey stoney i thought the dark period is when all the stretching occurs? no? dark will stop elongation?

i think that he means the lower temperature will slow growth not dark...

I'm unsure.I was just quoting the growfaq.Maybe they meant to put "stretch" in place of "elongation."

jordisgarden said:

Night temperatures should be kept above 60 degrees to prevent stress. It is preferable during flowering to have a night temperature drop of 10-20 degrees to stimulate flowering hormones and reduce stem elongation.


hey stoney i thought the dark period is when all the stretching occurs? no? dark will stop elongation?

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Fifty five will slow growth, it stresses the plant especially if you do it continually. Turning off you fan should cure your problem. My fan is on a timer, I let it run fifteen minutes after the lights go out to get rid of the residual heat. I put my air conditioner on energy saver at seventy two degrees. My nightime lows are around 68 and with my light on it's right around seventy five.

Plants do not absorb green light, they reflect it so a green light is good to use to go into your grow room at night.

snutter said:

This is an odd response. How does photosynthesis continue in the dark??? I don't understand....

Click to expand...

Actually there are two types of photosynthesis during the day plants burn CO2, during the night plants burn O2.

Drawing air from outside a thermostat would control this more accurately.Over this way many draw air from inside.So the fans can run 24/7 bringing in fresh co2 for the plants!And avoid any big temp changes.

if your growing in an outer building like i am, get yourself a thermostatic attic fan, and set it on about 80 degrees. get yourself a good digital thermostatic heater and set the temp on that around 70. setup this way, your room will stay the ideal temp during the day, and after oights out the heater will take over and keep the room where its supposed to be. if you have the proper lights, the correct amount of plants for your square footage,planted in the proper containers, and you have a fam moving the air inside, humidity and mold shouldn't be a problem

You should keep the plants between 70 and 74 inside. The main reason is below 75 degrees you won't have bug problems. Anything above 75 and there is a risk of bugs and mites. At night you can go down to 64 or a little lower. Run the lights at night if you are in a winter or cold climate. That will keep the room warm at night when the temps are down. If you are in a closet with no windows like me, I draw the air in from the living room with a centrifugal 175cfm 4" intake fan. A light with cooling is excellent for keeping temps down with lights on. In order to control everything with no windows buy a portable ac unit. Vent it into the attic. Soleus makes an 8000btu for 300 bucks at sears and it has heat in it also..This is the cats ass. Perfect temps all the time. Good luck and I hope this helps. Also make sure you put in and exhaust fan. You have to change all the air in the room every three minutes. I use a 475cfm exhaust 6" piping. Mine starts at the carbon filter hooks into the light to cool and gets drawn out the top of the room. Don't push through your light. It will build pressure. Always remember never push air, always draw it.

snutter said:

Yes, of course... Always a good reminder. The intake fan's power outlet is outside of my grow room, so no worries about light getting to them. I'd never go in to my grow room during the dark cycle unless it was a matter of life and death.

I've heard that you can use green or red lights and they won't effect the plant. Does anyone know if this is true???

-Snut

Click to expand...

DONT use red, plants still absorb on the red spectrum so this will disturb them. use the green lights, plants dont use the green spectrum so its not an issue