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Temperature/ Humidity

Discussion in 'General Marijuana Growing' started by LysergicBuds420, Feb 18, 2008.


    LysergicBuds420 Active Member

    What is the ideal temperature for maximum growth and prosperity for the vegetative state and flowering? I know some strands can prosper under different conditions but i just need a general idea. Thank you, any suggestions are appreciated.:blsmoke:

    david6767 Well-Known Member

    Ideally you are looking to maintain 75F during the lighting period.

    this should drop to 65F during the dark period.

    as for humidity you are aiming for 40-60%.

    matman4444 Well-Known Member

    My grow bible says temps about 75 are good, up to 85 are great, but over that is too much.

    uberpea Well-Known Member

    I hear aim for 75 Degrees. Of course give or take about 5 degrees and youre fine.


    growhappy Active Member

    so would it be fair to say that if the temps go into the 90's that it would slow the flowering development to a crawl? or even a stand still?

    bigd921 Well-Known Member

    not questioning the bible but I dont understand the thinking behind this in several places where weed grows outdoors naturally the temps can and do exceed 100, is it more about substained temperatures?? Even in nature during the course of the day you can have a 20+ degree temperature swing,
    Kevin the Great likes this.

    growhappy Active Member

    I think to flower it has to be cooler as well as have a 12/12 light. I checked the climate in mexico the summers there are "insufferably hot and humid as the norm. In consequent, Winter offers the most excellent beach weather as daytime temperatures average around mid-eighties while nighttime temperatures average around sixties". which also would be when it's dark longer at night. So it's not so much temps during the growth period, as it is during the flowering. I'm having a fit with mine right now. this year is hotter than the last 2 and I cannot get mine (haze #1) to flower worth a dam, it's been since mid march! it gets too hot even with an air conditioner and fans. I may have to wait until the temps naturally get cooler, but i've also had a massive bug problem (white flies and fungus knats) with the temps higher, the bugs hatch quicker. I have to spray eery 2-3 days. Flourescent lights are looking like a better option to work towards as with the temps rapidly rising yearly I can't imagine it will get better. is anyone else noticing an effect on their grows due to climate change?
    be more curious

    be more curious New Member

    Well I am flowering with 84temp40%humid. and the plant is thriving. 12/12 nights are about 61 with 22%humid

    makersknob Active Member

    Many right answers.

    Nature is not ideal. Imitating Ideal nature is ideal.

    77-87f daytime 19 hrs
    63-73f nightime 5 hrs

    this is perfection for North American and European Climate. Humans and Plants alike. (Think of the hand beneath the light to check light distance trick)

    Go by your plant. Obviously if it is Big Bud or NL for example these temps and times I present are perfect but for something like an equator breed you want to imitate more of that climate.
    Rabbi Reefer likes this.

    skunkyhead Member

    does anyone know what happenns if it's to cold? My ave on temp is 19-21 c w/ rh 58-60 Off time round 16c w/ rh of 45-50.
    Any ideas how to raise temp slighty? I switched off xhaust to see if it makes a differnce but i prefer to keep it running caus its my air supply :) ( Room runs at negative pressure) I have kept my osc fan on though. All Imput is greatly appriciated. :)

    I am aiming for 23-24 c bongsmilie:mrgreen:

    bigbudjohn420 Active Member

    hey i was just wondering if a high of 88 degrees with 55% humidity and a low of 66 degrees with a 28% humidity
    is this okay for growing marijuana .....:weed:

    wifi2voice Member

    I live near th equator and my temp is 92 during light and 88 at night and am having a hard time getting it to flower. Its been 2 weeks now and nothing. Its an Afgani.

    OldManPot New Member

    88 is to high, and 66 is to low for 88.

    you shouldnt have more tha a 10 degree drop in temp between day and night. even better if you can keep the temp within 5 degrees of daytime temps.

    shoot for a daytime high of 80 to 82

    nighttime 70 to 72

    if feeding CO2 you can raise the daytime temps some.

    LittleJohn Member

    I have been pondering this myself, Under the assumption that heat (in excess) will stunt or slow growth. Is a room that is 82-84F on average during the day with a Humidity of around 38-40% in any way going to slow/stunt growth? are these good growth conditions for the plant?

    nrusso23 Member

    my temps get about 86 f with my fans on anout 100 with the lights off humidy is about fourty

    wannaquickee Well-Known Member

    having temperatures fluctuate like that slower down growth. but they will still grow..

    iNFID3L Well-Known Member

    Id ALSO like to see an answer for this Q

    droman Active Member

    right now i am at 84degrees with 42% humidity. i am running an ac in there and if i urn the ac off after lights out the temp actually rises at night. curious if that is bad.. should i run ac all night? or will running a vent fan make this better than running ac all night

    Tlocsmokes Active Member

    I want to know the answer to this guys question ^^^.

    MEGAyielder420 Active Member

    High temp will most def slow down bud developement and high humidity will slow down production of trichomes as well. IMO ideal temps are about 70-75 and RH should not go under like 40 or over 60. This is the way I run my grows and have always had great success.
    puertorrican diesel likes this.

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