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Growing in the cold.

Discussion in 'General Marijuana Growing' started by JoeyV, Nov 3, 2013.


    JoeyV Active Member

    So what happens if a grow room cools to 60-65 degrees F (or lower) during the dark hours? I think the temp with the lights on will be in the mid to upper 70's, but as it's a new grow room it has yet to be tested.

    I know things get arid in an unvented closet. 2012's closet grow ended in May. Temps fluctuated between 78 and 90 from dark to light hours and the plants regularly thirsted for water as they were always warm.

    But a grow room a in basement that's not particularly well heated and winter on it's way, that's a new experiment. I've read on these pages that the cool damp environment could cause mold or bud rot, if I'm not mistaken. But I'm very leery of using a space heater for the dark hours.

    Any advice?

    hockeyrichard Active Member

    Eh I'm not sure but In my exp i set a sun beam warmer to 85 and pumped heat in no mold problems. Just Make sure it doesnt get to hot in there bc the Warmers using the Basement temp n not tent temp.Midwest location shitty winter and a shitty basement. Good weed though :)

    ~CReePeR~ Active Member

    Like ^hockey^ said, get a heater w/ a thermostat and set it to where you want the temp

    BustinScales510 Well-Known Member

    Some strains are more susceptible to bud rot than others, indica dominant plants with tight internodes and close clusters of dense buds are the most likely to get rot in cool damp conditions. 65 degrees during lights out isnt bad but below that (especially if humidity is high) could be troublesome. I have a dehumidifier running while my lights are out and I have the room exhaust slowed down..so the heat from that helps keep the temp in range.

    kermit2692 Well-Known Member

    90 degrees is too hot...probably won't have that problem in the basement but just a heads up..

    weedow Member

    if the cold weather already sets in, some growers are using heater in the grow room. marijuana plants love to grow in a temp. range of 21 to 29 degrees celsius. temp. hotter than this especially in mid to late flowering, photosynthesis can slow down. so, you still have to be very careful when using a heater

    JoeyV Active Member

    yeah, fighting the heat in a 2.5' x 5' closet with no way to vent the it was a bit of a challenge, even in the winter. There were days, and situations, that required the outer room to be closed. Temps in there, a 10'x10' room, got into the balmy mid 80's.

    It was nice in the dead of winter with temps below zero outside to have a warm zone in the house. But the space in the basement is roughly 3 times the square footage.

    Unfortunately, or perhaps fortunately, the room in the basement has a duct above it, which cuts the height from 7 to 6 ft... so not much vertical space, but we've gotten pretty good a keeping the height of our girls under control.

    The duct may be the answer to our heating needs. We gotta cut away some drywall and mount a vent and make it look nice and all... OR - some kind of heater. Anyone have any suggestions for a safe low wattage space heater?

    Uggg! more money and more work. At least this hobby has a definite payoff in the end...:eyesmoke:

    Turbanator Active Member

    Juzt keep it dry.i just rN 24 in celler under 3k hid no issues but u must keep shit dry

    GroErr Well-Known Member

    I'm in a cold area and growing in a cold room, in the basement. Keep them off the cold floor somehow, cabinet, skids etc. Lot's of air flow, humidity in the 35-45% range, temps in the 75-85F range. 60-65F lights off is no problem as long as you keep the other factors in check. They don't care where they are, they just care about temps, humidity, and water. These plants (pics) are in a cabinet, in a cold cellar, temps in cold cellar are 55-60F during the night when lights are on, 61-66F during the day when lights are off. Temps outside are 25-35F during lights on (at night), 40-50F outside during the day when lights are off. I'm now heating the cold cellar the cabinet is in to maintain the room temp and in turn cabinet temps to a minimum of 61F.

    Flipped them to 12/12 a week ago, cabinet lights on temps are 81-84F, lights off temps 61-65F, they're happy….

    Grow2-wk12-Day83-Wk1-Day6-Flwr-1.jpg Grow2-wk12-Day83-Wk1-Day6-Flwr-2.jpg

    JoeyV Active Member

    It' a new grow room. Gotta learn how to take advantage of the new setup. Running some preliminary tests now. So far the 324w T5 fixture is keeping the temp in the new room at 74F after an hour. Got the exhaust fan/filter on a thermostat set at 80F. It should kick on and keep the temp to around 78. However, it's not cold outside... low 50s. We'll see what happens in a few weeks.

    On another note, apparently my dumb-ass over watered the seedlings, so now they're stunted. They're barely growing at all. I'm gonna let the soil dry out before giving them any more water. But after two weeks they're only 2 inches tall, and a couple of them have barely broke through the top of the soil.

    Should've known better. This isn't the first time dealing with over watering. :wall:

    Oh well, I guess this grow is gonna take longer than I figured. Time to go smoke a bowl...

    spek9 Well-Known Member

    I like 65-67 at lights-off, and 77-80 lights on, never had an issue.


    DemonTrich Well-Known Member

    im a consistent 70-73* lights on and lights off. I grow in a basement, plus I have ac running when lights are on. my basement is 73-74* and 40% r/h :) perfect for growing and harvesting.

    JoeyV Active Member

    Got a digital thermometer with a high/low temp memory. It recorded a low of 50.2f last night. No lights, no fans, just a hepa filter fan on low. The temps dropped to the mid thirties outside last night.

    So, would wrapping the pots with some kind of bubble wrap or insulation help to keep the roots from getting too cold? They'll be about a foot off the floor once they start growing for real. They're in a small seedling cabinet right now but they got stunted a bit. Light Warrior runs out of nutes fast and I was slow to transplant. (must've been stoned...) Hopefully they'll recover and begin growing. Time is irrelevant, so a slow grow isn't a big deal to me, however, keeping the girls (and boys) healthy is. I plan on topping several times and trying to make them bushy, but since they were regular seeds, I don't know which are male or female. Hopefully I'll end up with 3 out of 6 female. It would really suck if none were female, thought that's pretty low odds. (less than 3%, i think)

    What about watering? My guess is they're not gonna need as much as if they were in a 90f closet.

    Always learning...

    RedWhiteBlueGreen Well-Known Member

    Thats quite a big room u got there to heat, and i never done as big myself (sadly!) but if they're worthwhile, i can offer 2 possible cheap-ish solutions.

    Firstly, have a browse for tubular heaters - i got one off ebay for £20 that runs at only 80W!! Its a 2ft long metal tube, with brackets & it gives off a good steady heat source - if u had 4 of those positioned correctly in room, they'd keep any chill at bay & raise it a few degrees certainly. They wouldn't blast it out if u needed big heat though, but i know u can buy 3 or 4ft ones that only cained about 100W as well. I'm in UK but guess u got same tho & probably cheaper in States.

    Second idea, was if u can't heat the whole room, then ur right that the most important thing to actually keep warm is the roots. If u can keep ur soil/pots/roots warm, then the plant can tolerate its body being alot colder, and will not suffer so much growth delay that cold could possibly cause to unheated roots. Could u maybe wrap ur pots in some sort of insulating jackets, or put them on mild heat mats? Its a cheap solution, tho to be fair it won't negate mould issues too well directly, but it will certainly ensure plant stays more healthy & vigorous enough to better resist infections in general.

    And maybe a combination of the 2 would be a cheapish, low power consumption option? Otherwise, i'll step aside for the big boys who actually know how to kit out whole rooms!

    Findaway New Member

    Im in a similar position I heard oil heaters are best because they can heat the air in a way that doesn't dry it out.
    Gonna put one on a heating thermostat that knocks off at an acceptable temp.
    Then just leave it and it only comes on when it needs to.
    Na meeen
    Clown Baby

    Clown Baby Well-Known Member

    get a dehumidifier and run your light cycle at night when it's coldest

    JoeyV Active Member

    Done! I was thinking of maybe getting a heated foot pad from amazon, but I'm not sure if it'll gas off or not. I really don't want to deal with the smell of that. That tube heater sounded nice, but it doesn't look like they have them here in the states. I can hang a 60 or 100w ceramic bird heater lamp in the room...I don't know...I'll figure something out. Thanks for the advice all.

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