when is cold too cold?

Do you think 55-60 is too cold for flower?

  • Yes

    Votes: 32 74.4%

  • No

    Votes: 11 25.6%
  • Total voters
    43
C

Connoisseurus Rex

Well-Known Member
nomofatum said:
Yes, it will be difficult to keep the other variable the same with the temp increase, you would likely need a sealed controlled environment. This is why it's important to let yourself learn from others who have the resources to do tests beyond your ability or willingness.
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I'm doing what I'm doing. The plants grow. I dunno what else to tell you.
 
nomofatum

nomofatum

Well-Known Member
Lets not just get caught up in the canopy either. Root temp makes a huge difference as well. If the roots are 50f they can't move the water/nutes as fast as they can at 70f. This can become your bottleneck too.

FYI, I had a set of DWC plants where I was pumping bubbler air from outdoors (very cold), water temps dropped into the lower 50's, plant growth dropped to less than half of normal. (this was veg)
 
C

Connoisseurus Rex

Well-Known Member
churchhaze said:
That's correct... The temperature of the canopy affects the rate of photosynthesis!! Good work!

It took you a while to come around, but I knew you'd make it!
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I never said it didn't. I actually said canopy temp is ideal, you can get your lights closer in 50 than in 70, which will also provide more lumens. You didn't read the whole thread before popping off.
 
unwine99

unwine99

Well-Known Member
Marijuana grows well in moderate temperatures – between 70° and 85° F (21°-29° C). Both high and low temperatures slow marijuana’s rate of metabolism and growth. Plants grow fastest when the temperature during the lighted period is kept between 72° and 77° F (22°-26° C). When CO2 is being used, the plant prefers to be a few degrees warmer, between 79° and 85° F (26°-29° C). Individual marijuana varieties differ in their temperature preferences by a few degrees, so some experimentation is required to find the ideal temperatures for the strain you are growing.

Ideal temperature is tied to light conditions. As more light is available, the ideal temperature for normal plant growth increases. Strong light and low temperatures slow growth and decrease stem elongation. Conversely, when plants are given high temperatures and only moderate light, the stems elongate.

At temperatures below 60° F (15° C), photosynthesis and plant metabolism slow, stopping growth as it waits for better conditions. As soon as the temperature rises, the plant resumes full functioning. When the temperature falls below 40° F (4° C), marijuana plants experience tissue damage and require about 24 hours of warmer conditions to resume growth. Young marijuana plants are somewhat tolerant of low temperatures; when outdoors, seedlings have been known to pierce snow cover without ill effect. But low temperatures during ripening, even just overnight, delay or prevent bud maturation. Some equatorial varieties stop growth after a few nights with temperatures below 40° F (4° C).

-- Ed Rosenthal


All I see is an arrogant little noob w/ a seedling talking in circles, equivocating and trying to rationalize his poor setup...completely ignored the photo I provided of a plant flowered in cold temperatures too btw.
 
2ANONYMOUS

2ANONYMOUS

Well-Known Member
Dr. Who said:
Dido that! How convenient he brings that up now.....
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what i find ironic ? is i read somewhere he is running 400 watts Correct me if i m wrong there Rex ???? @ 3 feet away from canopy in a tent how is it the canopy is 75 degrees which i question and tent staying at 50 - 55 so 5500 lumens i know which means nothing per sq foot and your going to have them temps on canopy,,
I Think your chasing your self now its ok just stop running let me get my boot back from booting you in the ass
Were all came in here to stop this non sense and give you some direction remember you only been growing for one year from looking at your history

HPS grow lights generate a lot of heat. This can be a serious problem in a confined grow space. Good ventilation is essential when using HPS grow lights (see also Cool Tubes below).“Grow room 2x3x72 his 400 hps raised his temperature by 30 degrees.”“A 400 Watt lamp
can raise the temperature of a room by 15 to 30
    • “ You will need excellent ventilation and possibly air conditioning”
  • The heat generated means that it is necessary to place the lights at some distance from the plant tips. Because light obeys the inverse square law, the further away the source of light is from your plants, the weaker it is. So light that is 2 feet away from the bulb is 4 times weaker than light at 1 foot away, and light at 3 feet away is 9 times weaker.
So this is what i mean yet when looking at your little plant it appears what you are telling us is totally different then what plant is telling me cause like CSI some people call me the plant whisperer lol
and your plant is telling me your full of it as there is no stretching my guess is there actually under T5 HO
 
GhostBud420

GhostBud420

Well-Known Member
Connoisseurus Rex said:
Optimum is what you, you're own personal preference, recognize to be right. I grow plants at low temps fine. You grow them at high temps fine. As long as both plants grow unaffected by temp, then the plants are growing at an optimum rate.

This is about the plants, remember? You're personal temp preference has no sway on what the plants can thrive in.
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You may be growing optimum for your conditions. But your conditions are not optimum. I dont see why you dont understand this... Its not a hard concept to grasp.
 
nomofatum

nomofatum

Well-Known Member
2ANONYMOUS said:
Because light obeys the inverse square law, the further away the source of light is from your plants, the weaker it is. So light that is 2 feet away from the bulb is 4 times weaker than light at 1 foot away, and light at 3 feet away is 9 times weaker.
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I just want to clarify the inverse square law and where/when/how it applies. It happens to be the most sighted but least understood scientific principle on these forums. What the inverse square law says is that as light spreads in an unconfined space the light will decrease in "density"/intensity by the factor of the distance squared. The distance squared is also the size of footprint the light would produce. Now when you line the walls with a highly reflective liner, the light can nolonger spread, and as a result it cannot reduce in "density"/intensity. So in the case of growing in a confined space, the inverse square law only applies to the distance the light will travel until reaching a reflective surface + an adjustment factor based on the reflectivity % of the material. If you had 100% reflective walls it would make no difference if the light was up 3ft or 30ft.
 
a senile fungus

a senile fungus

Well-Known Member
Those seedling pics in the beginning of.the thread look older than a week or so to me...

My seedlings are never that fast. Those look like >2wk pics and the claim is 9days... And supposedly they were germed in cold temps. I call BS on that.
 
2ANONYMOUS

2ANONYMOUS

Well-Known Member
nomofatum said:
I just want to clarify the inverse square law and where/when/how it applies. It happens to be the most sighted but least understood scientific principle on these forums. What the inverse square law says is that as light spreads in an unconfined space the light will decrease in "density"/intensity by the factor of the distance squared. The distance squared is also the size of footprint the light would produce. Now when you line the walls with a highly reflective liner, the light can nolonger spread, and as a result it cannot reduce in "density"/intensity. So in the case of growing in a confined space, the inverse square law only applies to the distance the light will travel until reaching a reflective surface + an adjustment factor based on the reflectivity % of the material. If you had 100% reflective walls it would make no difference if the light was up 3ft or 30ft.
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Well actually your saying is light distance should not matter then in a 100 percent reflective room to our eyes but yet for plants there is a huge difference
example 2 rooms identical 2 lights one placed 2 feet at the canopy in one room and 2 lights placed in other identical room placed 10 feet will growth be the same ??

That's the major difference between sunlight illumination and artificial lights. The intensity of sunlight doesn't change appreciable as you move up or down a couple of hundred feet. With artificial light this movement towards or away from the light source changes the light intensity dramatically.

If a one-watt light source is illuminating an area of one square centimeter at a distance of one meter, the intensity of light is 1 watt/SQ.CM. If we move the screen back to a two-meter radius the same light would be covering four times the area, reducing the light intensity to .25 watt/Sq. CM.

This is the inverse square law. The inverse square law states that the intensity of radiation is inversely proportional to the square of the distance from its source. So a doubling of distance reduces the intensity by 1/4th.
 
whitebb2727

whitebb2727

Well-Known Member
There is optimum temps of course.

My personal experience tells me a few things. I cut my teeth outdoors guerilla growing brick seeds. A lot of sativa's. Most have handled cold weather just fine, even in the 20's.

Do I think you need to grow in cold conditions? No. I do however think that cold spells effect the buzz. I personally think bud that has been hit by cold has a better buzz.

50's at night wouldn't worry me a bit. I've seen many a plant keep a trucking in colder temps.

Another thing is how fast they warm up with lights on.

I agree that cannabis has optimum temps to grow in. I'm also saying don't discredit the positives that cold imparts on cannabis.
 
nomofatum

nomofatum

Well-Known Member
2ANONYMOUS said:
Well actually your saying is light distance should not matter then in a 100 percent reflective room to our eyes but yet for plants there is a huge difference
example 2 rooms identical 2 lights one placed 2 feet at the canopy in one room and 2 lights placed in other identical room placed 10 feet will growth be the same ??

That's the major difference between sunlight illumination and artificial lights. The intensity of sunlight doesn't change appreciable as you move up or down a couple of hundred feet. With artificial light this movement towards or away from the light source changes the light intensity dramatically.

If a one-watt light source is illuminating an area of one square centimeter at a distance of one meter, the intensity of light is 1 watt/SQ.CM. If we move the screen back to a two-meter radius the same light would be covering four times the area, reducing the light intensity to .25 watt/Sq. CM.

This is the inverse square law. The inverse square law states that the intensity of radiation is inversely proportional to the square of the distance from its source. So a doubling of distance reduces the intensity by 1/4th.
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You share the common confusion/misunderstanding of the inverse square law. The law is describing how light spreads, it is not saying that light weakens as it travels. It's saying that at 2 ft away the light will fill a 4 sqft space and have 1/4 the intensity as if it were 1 ft away and filled 1 sqft. If it's 3ft away it will spread over a space of 9 sqft and be 1/9th as strong as if it were spreading over a 1sqft space... Get it? That is how the inverse square law works.

If the walls confine the light to 16 sqft, it doesn't matter if the light is 5 ft up, it still can only spread to 16 sqft, so it will be 1/16th as intense as 1ft away, not 1/25th.

In reality having the light a bit higher than the plants require is better as it give more room for the light to spread more evenly, while still delivering the same par watts per sqft.
 
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2ANONYMOUS

2ANONYMOUS

Well-Known Member
No one said cold temps do not influence certain aspects or bring out certain traits
I mean i have a old BB strain older then DJs shorts BB that i can influence different traits meaning if i run hotter temps i can bring out the sativa side of the plant ,, when i run temps cooler i can bring out the indica side of the strain..
goal here is to now breed both sides and see if the off spring will be on either indica side or sativa side dominance .. Environment plays a huge factor in all things
 
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