Freezer grow first grow- help with temperature control

*I first posted this in the indoor growing section but realized this would be a better location for my question.

My setup-
20"D x 27"W x 60"H vertical freezer
6" Vortex S-line 347cfm inline exhaust fan
4" ducting for exhaust
Titan controls zephyr1 temp controller
Currently 1 3" Passive intake
CAN33 carbon filter
5- 2ft HO T5 6500k grow lights
Will add 2 or 4 clamp on CFL bulbs in flowering (Possibly LEDs down the road)


I'm about ready to start my first grow in my brand new used rebuilt freezer grow box. I have a few questions regarding ventilation. I realize my exhaust fan and carbon filter is probably overkill right now but longterm I will have a bigger spot to flower and will use the freezer to maintain a mother.

The freezer is in my garage which is currently not tempeture controlled. So it will be using the ambient air in the garage
at this time it's not ideal to run ducting from house to garage) The next few months will range anywhere between 50° highs 0° lows. So I'm afraid I will he fighting to keep my box warm enough all winter. I'm open to suggestions to combat this problem.

Does my exhaust fan need to run 24/7 to constantly exchange the air inside the freezer? Or can I use a thermostat that will control the exhaust to turn on when the temp hits say 80 degrees? I would have a small desk fan running to circulate the air inside. My concern is when my lights are off the temp will either drop too low and damage my plants or the exhaust fan would not turn on and my plants would not receive enough fresh air. Any suggestions or helpful tips would be appreciated. Thanks.

I had a similar issue when I first started. I bought an autopilot environmental controller ($180). You can then buy a small heater, which you plug in to the air conditioning outlet on the controller. You can set a range for the temperature to be at, and the controller will power on and off the heater accordingly. It's always good to have some sort of circulation in your room, so if it's very cold then maybe an exhaust fan isn't necessary. You can keep a small fan inside the fridge for circulation, and maybe keep the hole for you exhaust fan open. or put some sort of filter on it so it can vent but not allow the penetration of light inside the fridge while their sleeping! Hope this helps you, if you have anymore questions just ask

FLOOR TEMPS! A small fan in there is gonna be a must.

I vegged in a garage for a bit, even CFLs in the small space should keep the air pretty warm. Just make sure the freezer is on towels or something that will keep the floor temps from getting too low, especially if youre DWC, as your rez will get too cold.

Get better spectrum for flowering. You dont need HID, no matter what the masses say. IMO you definitely want 2700ks when its time to flower. Appollo horticulture sells some good priced monster CFLs in 2700k. Nugs wont be dense, but you can get the bulb up close, lower bud sites get pretty good growth.

If your freezer isnt 100% airtight from the modifications, I wouldnt worry about your plants not getting enough fresh air at night. They are much more resilient in veg, especially if you can get them transplanted from seedlings prior to putting em' in "the chamber". I dont have experience with these, but maybe just get a Co2 bag?

IamLordeYaYaYa said:

FLOOR TEMPS! A small fan in there is gonna be a must.

I vegged in a garage for a bit, even CFLs in the small space should keep the air pretty warm. Just make sure the freezer is on towels or something that will keep the floor temps from getting too low, especially if youre DWC, as your rez will get too cold.

Get better spectrum for flowering. You dont need HID, no matter what the masses say. IMO you definitely want 2700ks when its time to flower. Appollo horticulture sells some good priced monster CFLs in 2700k. Nugs wont be dense, but you can get the bulb up close, lower bud sites get pretty good growth.

If your freezer isnt 100% airtight from the modifications, I wouldnt worry about your plants not getting enough fresh air at night. They are much more resilient in veg, especially if you can get them transplanted from seedlings prior to putting em' in "the chamber". I dont have experience with these, but maybe just get a Co2 bag?

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I'm not sure if you can tell from the pictures but it's a commercial freezer, that being said all the "guts" are stored below rather than up top or inside compared to household freezers. There is at least 12 inches from the inside floor of the freezer to the concrete floor. Do you still think this will be an issue?

I plan to switch out 3 of the 5 T5 bulbs to 3500k spectrum when flowering begins, in addition to 2 clamp on lights with splitters also holding 3500k Cree LED bulbs. May even add a reptile UVB bulb per fishdeth's thread.

I am interested in adding Co2. I haven't done much research on this yet. Fishdeth also grows in a freezer and he made a homemade Co2 bubbler. I may go that route to begin with. Thanks for tips.

Krusher said:

I'm not sure if you can tell from the pictures but it's a commercial freezer, that being said all the "guts" are stored below rather than up top or inside compared to household freezers. There is at least 12 inches from the inside floor of the freezer to the concrete floor. Do you still think this will be an issue?

I plan to switch out 3 of the 5 T5 bulbs to 3500k spectrum when flowering begins, in addition to 2 clamp on lights with splitters also holding 3500k Cree LED bulbs. May even add a reptile UVB bulb per fishdeth's thread.

I am interested in adding Co2. I haven't done much research on this yet. Fishdeth also grows in a freezer and he made a homemade Co2 bubbler. I may go that route to begin with. Thanks for tips.

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Krusher, take it slow with the CO2. Not every situation calls for it, as there is CO2 naturally in the air.

your not putting out enough light to need supplemental CO2 DONT WASTE YOUR MONEY! There is a way for you to control it all with a thermostat an AC contactor and a 24 volt transformer witch can all be configured to turn on and off with temp. Ill post the schematic if you want. its very easy and straight forward wiring.

Thanks for the advice fellas. I purchased a small space heater and I have the thermostat dialed in about where I want it. I think I have the temp under control for now. Lights on high is 80, lights off low is 74. Humidity has been 28 high and 12 low.

I have also increased the intake hole from 3" to 4" and I've added a dryer exhaust with vents that close when the fan isn't running. After doing this there was quite a bit of light leaking from the intake. I had some flat black spray paint so I painted the inside of the duct and also the backside of the flaps. That worked great. I will also be adding a filter to the intake to keep pests out and smell down when the fan isn't running. It's the kind they sell at Home Depot that has the layer of carbon built in.

The freezer is now sealed up, light leaks are fixed, and (hopefully) climate controlled. I'm ready to put some ladies into thier new home. I'll start a new post if anyone wants to follow along and help a noob out with his first grow.

Quick question on the Co2. I realize I don't have enough light output at this point to add Co2. But I'm planning to veg and train them for at least 4-5 weeks and by then uncle sam might give me some of my hard earned money back. I've been looking into some lighting upgrades. Either DIY cobs or I like the California Lightworks Solarstorm 220. At that point would Co2 be beneficial?

Krusher said:

Quick question on the Co2. I realize I don't have enough light output at this point to add Co2. But I'm planning to veg and train them for at least 4-5 weeks and by then uncle sam might give me some of my hard earned money back. I've been looking into some lighting upgrades. Either DIY cobs or I like the California Lightworks Solarstorm 220. At that point would Co2 be beneficial?

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No need for co2. You need to get yourself a hps which will give warmer light and better buds. If you are willing to spend on co2 you'll must have funds for a hps grow light. You can get good results with a 100-150 hps from Home Depot or something

Hps or Mh is not an option in this case. For such a small space the heat would become a major issue come warmer weather. I'm stuck on LEDs for for these reasons, less heat, less energy consumption, highly efffecient, and they're fairly priced for my application (small space). From what I've read LEDs can achieve specific spectrums of light that the plant will thrive off of. The same can not be said for any HID light.

This is the type of CO2 setup I am referring too. This picture is from fishdeth first freezer grow.

Krusher said:

Hps or Mh is not an option in this case. For such a small space the heat would become a major issue come warmer weather. I'm stuck on LEDs for for these reasons, less heat, less energy consumption, highly efffecient, and they're fairly priced for my application (small space). From what I've read LEDs can achieve specific spectrums of light that the plant will thrive off of. The same can not be said for any HID light.

This is the type of CO2 setup I am referring too. This picture is from fishdeth first freezer grow.View attachment 3568850

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Led is great. But I said hps to add heat for now. You can get a hps for really cheap. Your adding a heater which in turn is using more energy to do what a small hps will do plus better light...then in the summer get your led or use the t5.