[sir rance alot]

How critical is night time temperature drop and what if you cant get a temp difference?

How is this going to affect flowering?

My new set up now lets my temps stay the same if the lights are on or off.

[compost]

That is a good question I can't give a good answer to. I just recently switched from a sealed room and now my daytime and night time temperatures are very close. Ive searched around and can't find a whole lot about what effects it has. Would any of the experts chime in on this one?

[pezmasterelite]

Hi,

I think if your night temp does not drop, this will cause your plants to stretch less. If you night temp drops like 10F or more from the day temp, then your plants will be a little more lanky and stretchy in comparison to those grown with constant day/night temps.

here is a link for the above statement, not sure if we can reference another mag, but here it is.

https://www.cannabisculture.com/v2/articles/1536.html




The following things are from:

Marijuana Horticulture the indoor/outdoor medical grow bible
Jorge Cervantes
(1) pg. 247
(2) pg. 319
(3) pg. 320

(1) says that large fluctuations will cause slow growth and development in general.

(2) says that drops of more than 15F can cause unwanted build-up of humidity. Colder air holds less humidity, so you may create dew in your grow room.

(3) has some useful info, basically stating that the plants will have more even, strong, and healthy growth with constant temperatures. The plants oxygen uptake/metabolism is regulated somewhat by the temp, so that should be good to have constant room temp.

Peace.

[3rdEye]

sir rance alot

This https://www.icmag.com/ic/showthread.php?t=194053 thread has an excellent discussion and information about controlling stretch in plants using temperature and light spectrum manipulation. You'll get lots out of that.

[bluepeace]

My room wants to run a constant temp but lately, I've been running my night temps down to 61-63 and day temps at 78-81. About 4 days after setting new lower night temps a few of my plants started to change color, some dark almost black, others dark purple.

[zbenjii]

i'm curious what night time temps being greater than day time temps would do.

[MIway]

Originally Posted by zbenjii

i'm curious what night time temps being greater than day time temps would do.

That's the whole practice of 'the dif'... or differential. There was/is evidence (?source) that if the night temps are a few degrees higher (2~6) than the day temps, the nodal stretching is significantly less. Think they use this tech in commercial nurseries, e.g., poinsettias.


Personally, having the night temps just as high as the day temps is a big plus as to avoid temp drops leading to spikes in RH... trying to avoid the germination of mold. 80 during the day... 84 at night... right from when the lights drop, the temps rise... or so is the goal.

[Space Case]

Originally Posted by MIway

Personally, having the night temps just as high as the day temps is a big plus as to avoid temp drops leading to spikes in RH... trying to avoid the germination of mold. 80 during the day... 84 at night... right from when the lights drop, the temps rise... or so is the goal.

This is where owning a commercial grade dehuey (Santa Fe) comes into play, versus a cheaper portable dehuey from the hardware store. The cheap ones can't pull moisture out of the air when the air goes below ~65º F or so. The commercial dehueys can still dehumidify down to 40-45 degrees, and additionally put out some heat.

Cold night temps with warm day temps will cause your plants to stretch like crazy, especially sativa dominant plants. This stretching is mostly undesirable, unless you have really high ceilings, enough space, and can accommodate the stretch. After the stretch period, cold night temps will actually impair budset and hurt your yields. My understanding has always been to keep your day/night temps within a 10 degree range of each other, but if you can really keep it warmer when the lights are off, do it! Heaters on a timer is what does the trick for me. Only if you are trying to bring out some colors and YOU HAVE THE HUMIDITY IN CHECK, can you start to drop the night temps during the final weeks of bloom. However, I have found in my experience that this is a lock-out induced color change and will affect your final flush, as P is locked out and cannot be used by the plant. If you want purple colored buds, grow strong purple genetics that will turn color in 85 degrees.

[Buddler]

Originally Posted by MIway

That's the whole practice of 'the dif'... or differential. There was/is evidence (?source) that if the night temps are a few degrees higher (2~6) than the day temps, the nodal stretching is significantly less. Think they use this tech in commercial nurseries, e.g., poinsettias.


Personally, having the night temps just as high as the day temps is a big plus as to avoid temp drops leading to spikes in RH... trying to avoid the germination of mold. 80 during the day... 84 at night... right from when the lights drop, the temps rise... or so is the goal.

Originally Posted by Space Case

This is where owning a commercial grade dehuey (Santa Fe) comes into play, versus a cheaper portable dehuey from the hardware store. The cheap ones can't pull moisture out of the air when the air goes below ~65º F or so. The commercial dehueys can still dehumidify down to 40-45 degrees, and additionally put out some heat.

Cold night temps with warm day temps will cause your plants to stretch like crazy, especially sativa dominant plants. This stretching is mostly undesirable, unless you have really high ceilings, enough space, and can accommodate the stretch. After the stretch period, cold night temps will actually impair budset and hurt your yields. My understanding has always been to keep your day/night temps within a 10 degree range of each other, but if you can really keep it warmer when the lights are off, do it! Heaters on a timer is what does the trick for me. Only if you are trying to bring out some colors and YOU HAVE THE HUMIDITY IN CHECK, can you start to drop the night temps during the final weeks of bloom. However, I have found in my experience that this is a lock-out induced color change and will affect your final flush, as P is locked out and cannot be used by the plant. If you want purple colored buds, grow strong purple genetics that will turn color in 85 degrees.

Great posts didn't know bout the purple being a lock out though always thought it was genetic and cold night temps ..

[Space Case]

Originally Posted by Buddler

Great posts didn't know bout the purple being a lock out though always thought it was genetic and cold night temps ..

Its both!