L
Legalize This
How low of a temp, is too low, for the 12 hours of darkness?
L
Legalize This
really? 72? well, how do you get the purps, and what can happen if it gets too cold? can it go to totally male, because i think thats what just happened to me. see my northern lights. beautiful MALE. im in the sierra nevadas too, and my grow room gets 58 at night sometimes. i bought it as a feminized seed from holland or amsterdam.
BlueHaze
Active member
The easiest and most under-used way to control internodal stretch is temperature control. Plant internodal length is directly related to the difference between day and night temperatures – the warmer your day cycle is as compared to your night cycle, the greater your internode length will be. The opposite also holds true; the closer your day and night temperatures, the shorter your internodes will be. Ever notice how as the warmer summer months approach, your plants begin to stretch? Part of this problem may lie in an overall hotter grow-room, but a larger factor is the increased difference between day and night temperatures.
Lets look at putting this to play in your grow room. Maximum temperatures should ideally never rise above 26°C, so you must do everything you can to prevent your room getting too hot (run lights at night, use exhaust fans, air conditioners, etc). An ideal temperature range is 24-25°C when the lights are on, and 22°C when the lights are off.
The temperature technique is most effective under a 12/12 light regime, which is ideal as this is when cannabis stretches the most. When the light cycle is brought to 12/12 we will raise the night temperature to the daytime level of 24-25°C. Space heaters on timers work well for this, and max/min type thermometers are ideal for
tracking temperatures.
It is during the first 2-3 weeks of the flower cycle that most strains begin to lengthen internodes, making it a very important time to control temperature, as this is when the framework for future colas is built. After this 2-3 week window we need to drop the night temperature back down to 22°C, as this is where the plant is happiest.
As floral development begins we need to keep in mind that the total size of your buds is determined largely by average daily temperature, provided it does not exceed optimal. So if you are letting your day temperatures drop below 24°C or your night drop below 22°C, you are costing yourself in overall weight and harvest.
Once your buds have reached optimal size and and you have begun the flushing period, you may consider dropping temperature down to 17-19°C for the final week or two. This drop in temperature triggers anthocyanin production, which intensifies the colour of the floral clusters and makes for a showier bud, especially with "purple" varieties. This final temperature change is not always feasible and can be omitted.
For extreme height control you may even use warmer night temperature than day, but be very careful when running settings like this, as even a zero difference between night and day temperatures will lead to leaf chlorosis (yellowing) after 2-3 weeks.
Lets look at putting this to play in your grow room. Maximum temperatures should ideally never rise above 26°C, so you must do everything you can to prevent your room getting too hot (run lights at night, use exhaust fans, air conditioners, etc). An ideal temperature range is 24-25°C when the lights are on, and 22°C when the lights are off.
The temperature technique is most effective under a 12/12 light regime, which is ideal as this is when cannabis stretches the most. When the light cycle is brought to 12/12 we will raise the night temperature to the daytime level of 24-25°C. Space heaters on timers work well for this, and max/min type thermometers are ideal for
tracking temperatures.
It is during the first 2-3 weeks of the flower cycle that most strains begin to lengthen internodes, making it a very important time to control temperature, as this is when the framework for future colas is built. After this 2-3 week window we need to drop the night temperature back down to 22°C, as this is where the plant is happiest.
As floral development begins we need to keep in mind that the total size of your buds is determined largely by average daily temperature, provided it does not exceed optimal. So if you are letting your day temperatures drop below 24°C or your night drop below 22°C, you are costing yourself in overall weight and harvest.
Once your buds have reached optimal size and and you have begun the flushing period, you may consider dropping temperature down to 17-19°C for the final week or two. This drop in temperature triggers anthocyanin production, which intensifies the colour of the floral clusters and makes for a showier bud, especially with "purple" varieties. This final temperature change is not always feasible and can be omitted.
For extreme height control you may even use warmer night temperature than day, but be very careful when running settings like this, as even a zero difference between night and day temperatures will lead to leaf chlorosis (yellowing) after 2-3 weeks.
forty
Active member
....and feeding them properly.
dj_greenthumb
Member
Nice post, BlueHaze. Rep+!
I'm stoned right now but I'm pretty sure that all my best grows have been with about a 20* temperature spread.
I'll check later just to be sure though cause I'm stoned right now. I might just be running under the 20* spread because the temperatures work better and are cheaper and easier to maintain than a consistent 74*and the buds are way frostier... But I've always disagreed with the books about some of the printed optimal growing conditions anyway, so it wouldn't surprise me.
If temperatures high 85*F during the light period it will help avoid some pests, like PM. PM won't grow in temps above 75*F so even if your set is infected with PM you can still grow it without problems.
If temperatures drop to the low 60's at night it is beneficial also. Resin production is multiplied dramatically, spider mites, thrips, white flies and many other pests become lethargic and inactive in lower temperatures.
But it stands to logic tho that maybe I started using the 20* swing because it makes it easier to maintain lower root temperatures. Cause about 65*F is about perfect for root zone and allows better oxygenation of the water supply too.
I don't know because I'm stoned right now, but I know there is a good reason that I use a 20 degree spread, the same as I try for between the ambient room temp and the root zone.
I'll check later just to be sure though cause I'm stoned right now. I might just be running under the 20* spread because the temperatures work better and are cheaper and easier to maintain than a consistent 74*and the buds are way frostier... But I've always disagreed with the books about some of the printed optimal growing conditions anyway, so it wouldn't surprise me.
If temperatures high 85*F during the light period it will help avoid some pests, like PM. PM won't grow in temps above 75*F so even if your set is infected with PM you can still grow it without problems.
If temperatures drop to the low 60's at night it is beneficial also. Resin production is multiplied dramatically, spider mites, thrips, white flies and many other pests become lethargic and inactive in lower temperatures.
But it stands to logic tho that maybe I started using the 20* swing because it makes it easier to maintain lower root temperatures. Cause about 65*F is about perfect for root zone and allows better oxygenation of the water supply too.
I don't know because I'm stoned right now, but I know there is a good reason that I use a 20 degree spread, the same as I try for between the ambient room temp and the root zone.
TonyGreenHand
Active member
Yes wonderful post bluehaze!
A higher night temp leads to larger nuggets, always shoot for a low night/day temperature differential!
A higher night temp leads to larger nuggets, always shoot for a low night/day temperature differential!
snaggy-
Member
I'm with stress test on the bug control factor of colder temps. Had a really bad infestation, sprayed with neem once up here, and they were gone within a week. Down in LA when I was growing in a beach town the mites lingered and ruined a small crop of mine.
If only the cold got rid of fungus gnats. Those fuckers are giving me HELL in coco.
I really do need to at least get the lights off temps up to 60-65 though.
If only the cold got rid of fungus gnats. Those fuckers are giving me HELL in coco.
I really do need to at least get the lights off temps up to 60-65 though.
L
Legalize This
thanks
Slimm
Member
L
Legalize This
alright, sorry for that. yea, people keep riling me up with info that i know is false. my air unit is set to 84. if it ever reaches that, it cuts on and cools to about 80/81. so 81-85. my night temp with no heater can go down to 48/50. it varies. i have a 200 watt heater from walmart now that keeps night temp at 78-80. will NO difference matter? im thinking not. because in summer, i dont really have a problem, but theres still a drop of at least 20*.
L
Legalize This
what i need is a simple unit that u plug in, and when the temp gets too low, it turns my heater on. thats all i need. all of these environment regulators do all kinds of other things that i dont need. what i need should only cost like 20 bucks, not $387.89.
L
Legalize This
i would like to challenge this theory. i think its related to distance from the light, and the distance from the sun durring spring/fall times. when i put my plants 12" from the light, it grows 2" then i drop it 3" etc. my stalks are always thick and nodes are very close together. i used to keep the plant 15" from the light, and it grew normal. i have a stalk laying outside that im going to take a pic of, where i grew it 10" from the light, and its the thickest stalk i ever had, and the nodes are about 1/4-1/2 " apart.
L
Legalize This
thats it. root temp has to be regulated, and air temp has to be "somewhat" regulated. thats going to work better for me.
