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Need Cheap Heat Source To Keep My Plants Warm

Discussion in 'General Marijuana Growing' started by jessie.diamond, Nov 13, 2009.


    jessie.diamond Member

    Hi All,

    My plants are in a pre-fab grow room in an attic, and now it's getting cold. That's no problem when I was in the vegetative stage, because both of the CFL's (85 watt and 100 watt) kept the little pre-fab grow room warm enough. (I ran the lights 24 hours a day, which they seem to like just fine--as have a previous grow.)

    But now, I'm getting near the 12/12 time . . . and it's going to get much too cold inside the pre-fab room during the 12 hours the lights are off.

    I'm sure someone will have an easy, cheap, and maybe even creative way to keep that little grow room warm during the lights-off time.

    My second question is whether the plants look about a week away from 12/12, or are they ready now?


    I know they grow about 1/3 bigger during the 12/12, and that would close to fill the little grow room if I started now. (I know the front plant isn't doing as well as the other two, but that's mainly because it got planted about two weeks later.)

    My third question is this: these were from a mixed bag of feminized seeds. Can anyone identify the plants, yet? Or will we have to see them in full bud, before someone with a good eye could tell.

    So, any ideas for heating it? Would you give them another week before 12/12. And are identifiable to anyone yet?



    Phatoptimo Member

    Looks like you got 2 cross breeds and 1 heavy indica. I like to rub the stems and smell your fingers. Is it a sweet smell or funk? Each plant will have a diff smell. This can give you an idea what its gonna be like. Not sure what to do about your heating issue. Maybe move your tent or make a bigger tent where you can get a heater in there IDK never used a tent soo...

    jessie.diamond Member

    As mentioned, my pre-fab grow tent is in the attic and 1) it's getting cold up there, and 2) I'm getting close the the 12/12 stage. So, when my lights go off for twelve hours, the temp will drop quickly . . . maybe to 40- or 50-degrees.

    What can I stick in the tent that would keep it a bit warmer while the lights are off?




    super2200 Well-Known Member

    What room is below the spot in the attic? is there not a way to block some of the venting in the attic to keep the wind from blowing right through, if there was a way to vent any of the heat from the room below into the tent it may help, the resivour is what I would worry about more than the foliage, the tank may get too cold, possibly an aquarium heater in the tank would maintain the roots at warm temperature, the foliage may be able to handle it fine if your tank is warm

    MaintMan Well-Known Member

    Hey man just do what I do, heat with your lights( well a new one) I know your like I have to keep it dark. Yes you are right but there is no rule that says you can't build a small box for your plants to sit on with a light inside ( box be light proof of course) the box light comes on when thenlights go out and keep the tent warm with somewhat of radiant heat.

    I use two lights for mine bc I'm in a basement and it's veging cold here too and the wals and floor are cold. I throw a 600 on when lights are on and a 250 with lights off but I have a 14long by 7+ tall by 4 ft wide room to heat.

    Trust me it wil work and u won't Need much, cfls will give you enough heat without causing a fie hazard bun to be safe I'd take temp readings in the box after x amount of hrs over a diff period of time

    riddleme Well-Known Member

    a small space heater, you can get em at wally world for as little as $15

    super2200 Well-Known Member

    Looked like hydro, so you should start with the aquarium heater to ensure you mantain root temperature. The foliage can take it probably as long as there is no open wind on them in the attic

    MaintMan Well-Known Member

    Small space heaters will suck the humidity right out of the tent and prob kill his plants. To combat that he would need to have an evaporitive type humidifier ( steam and electronics don't mix in small spaces) which will blow coldish air defeating the purpose of the heater for the mist part. Not to mention that almost all those heaters are 1500 watts on high and around a thousand on low. If you are infact running straight hydro and not a feeding system, then I'd say I'd agree with an aquarium heater. I still think a 4-6 inch tall ply wood box that will cover the grow area with maybe 2-4 13 watt bulbs spaced out 1- 2 on each side. A 4x8 sheet of plywood is 6-7 bucks max and a couple of cheep lamps from the salvation army or resale store or yard sales a will power the lights so you don't need to wire anything in you just need a outlet for two more plugs, so a power strip will prob be needed bc I know most houses gave limited uf any power in attic. You should be able to build and power the box for less than 25 bucks and it will only draw tfe wattage of the lights! Not 1000-1500 watts

    uwill3 Member

    Ebay has heating pads wet/dry going for about $25, which is less of a fire hazard, and will keep your reservoir at the desired temp...

    I would recommend the heating pad be set to MED, and put on a timer (while lights are off), although I leave my heating pad on for my clones continuously, and its a small dome compared to the big reservoir, but no matter what you decide, your plants will adapt to their environment, as long as it is consistent.

    If the light is keeping the plants warm enough, with your 24 hrs of light, then keep the two smaller ones in VEG, and put the one big one into flower in a different area w/ a heated pad... This will also be doing you a favor in the end... because right around the time your going to harvest, you will be ready to throw the next plant into flower.... Always remember to seal open holes to the top of your reservoir, any light getting in, will cause harm to the existing plants roots, causing all kinds of unwanted bacteria to grow in there.

    Your plants wont show their sex until the flower stage, unless something goes wrong with your lights, etc... White or green balls, are a bad sign, if they have already popped open your other plants might yield seedy pot. Hairy tops, are a good sign.

    One last thing to add to this... It looks like your using a full spectrum flood light, which works for VEG, but for Flowering, they suck... I know from personal experience, that the Floros just don't put out enough red spectrum light... I know they are expensive, but a HPS (high pressure sodium) light will put out enough red spectrum to almost double your yield... You will be lucky to get 7grams from a plant w/ floros only, but with a hps, you can get 14 to 18 and more, if you use substitute nutrients for the flowering state (such as a product called 'enormous' hence the name).

    Good luck

    jessie.diamond Member

    I solved the heat issue: I got a long length of tube, ran it to where the heat collects in our house, and my little computer fan draws the hot air in while the lights go off.

    As for the Kelvin issue, thanks for the tips. I bought two big CFL's (85 and 100 watt): one is in the lower end and one on the higher end of the spectrum for mj. Giving so much info on the kelvin issue, some of which is contradictory, I've been running both lights for both stages.

    I'm sure I'll learn a lot as I go along. It's only my second full grow, and I'm enjoying the learning process.


    alisonW Member

    Great idea on the recycled heat from your computer! I'm doing my first grow, so much trial and error going on. I just put a crock pot full of water in my room and I'm watching the temp to see the result. It seems like a little tropical paradise in there!
    Good luck..


    Woomeister Well-Known Member

    Dog whelping blanket heat pads and aquarium heaters for the reservoir.

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