With Winter upon us this subject seems to be coming up often with newcomers. I thought I would gather my notes and document how I manage to maintain my temperatures in my cold climate.
With this setup I can maintain temps in the mid 70Fs with 50% rH in an uninsulated, unheated metal shop in the Pacific NW with outside temperatures as low as the upper 20Fs.
5’x5’x8’ Gorilla Grow Tent Original • Spider Farmer SF4000
The tent sits on four 3’x4’ 1/2” thick rubber stall mats. These are found at any farm, tractor supply store. They are VERY heavy, dense rubber mats for animal stalls and insulate from the cold concrete. They also make 4’x6’ 3/4” version but my bad back can’t handle that weight and I was in a hurry. Did I say they were HEAVY.
I use 7 gallon fabric pots in 16” saucers and up on 2” risers. The pots air prune the roots (no roots wrapping around pot) and it’s hard to overwater because they help dry out the soil faster. I’m doing Nature’s Living Soil so I want all nutrients to stay in the pot. Therefore I remove the risers to water, and once the runoff in the saucers wicks back into the pot (usually the next day), I put back the risers to speed up drying out. Watering ended up being veg 2-3 days and flower 3-4 days.
This seems to help manage the correct level of humidity, I do not use a humidifier or dehumidifier at this time. Things may change when the hot weather comes. I do have a small portable air conditioner that might be useful then. We used it in our camping trailer but that’s gone.
Environment: First Grow - Fall and Winter
I started the grow 01 October and quickly found I wasn’t keeping temps and rH where they needed to be when temps plummeted in the middle of the month from the 50s at night to the 30s. I struggled for nearly 2 months to get a working system and my plants were shocked and stunted. I was afraid I would loose them, they looked terrible. All yellow and twisted leaves. By late November things were being dialed in and the plants were starting to look better.
Equipment Setup
My instruments are set to maintain the numbers in this GWE chart.
I keep it on my phone.
AC Infinity T8 fan and carbon filter maintains consistent environment when things get too high. I know that’s not what these fan are designed for but it works awesome and periodically brings in fresh air.
NOTE: this is the OEM controller that came with my fan in September 2020. I’m upgrading to the new Controller 67 for my next grow and will update this section once I have it.
750w Oil-Filled Radiator with Inkbird Temp Controller Programming the Inkbird 308 VIDEO
1500w Milkhouse Heater with Inkbird Temp Controller
Floor 8” Oscillating Fan
Ceiling 6” Clip-On Fan
8 Outlet Surge Protector with Mechanical Timer
Control Wall
The two Inkbird sensors, the ACI sensor and the Govee hygrometer all hang banded together above the canopy using a standard ratchet rope hanger so I can raise the height. This maintains a consistent reading for all 4 sensors.
Calibration: All controllers have calibration settings to bring them all to the same temperature number. They should be together when doing this so they are all reading from the same spot in your tent.
Rh is usually not a problem here in the great north-WET, but on occasion when it drops low I either water the plants or place some water in the saucers to evaporate and that puts it right.
This is the control wall. You can see the rope hanger holding all the sensors at top right. I originally had them spread out but found better control with them all together sitting at top the canopy.
In these images, you can see the radiator in front of the intake window, the milkhouse heater to the left of it and the floor fan to the right of it. The milkhouse heater is not facing the plants so as not to dry them out to much. The floor fan oscillates in a 90 degree path, from along the heater wall, across the room and to the back wall. It is angled slightly up to blow the branches and leaves.
The upper fan is straight up from the floor fan and angled to push the air down towards the opposite corners and walls.
Note: after this grow I plan on moving the ACI fan setup to along the opposite wall of the heaters and straight up above the water wand. This was the first piece of equipment I installed upon setting up the tent and I’ve found I would like to expose more of the ceiling poles for the light hangers.
Outside the tent to the right is a 4’ table with a 20 gallon food-grade water barrel with brass spigot, 10’ garden hose and water wand. The hose enters the tent at the bottom through one of the sock openings. It’s gravity fed. Both the spigot and water wand have turn-off valves to prevent accidental flooding. I keep it hung using the cable hanging from an upper sock opening. The ACE brand wand is the best I’ve ever owned. The shower setting with the mild flow of water gets everything evenly wet without washing the soil around. Note: the only negative points in its review were some people cracking the threads in the handle from connecting and disconnecting the hose. I added a brass quick disconnect from ACE to prevent this from happening. Be sure to use plumbers teflon tape on all threads.
Images from my weather app and the Govee hygrometer.
Here they are today, week 7 into flower.
With this setup I can maintain temps in the mid 70Fs with 50% rH in an uninsulated, unheated metal shop in the Pacific NW with outside temperatures as low as the upper 20Fs.
5’x5’x8’ Gorilla Grow Tent Original • Spider Farmer SF4000
The tent sits on four 3’x4’ 1/2” thick rubber stall mats. These are found at any farm, tractor supply store. They are VERY heavy, dense rubber mats for animal stalls and insulate from the cold concrete. They also make 4’x6’ 3/4” version but my bad back can’t handle that weight and I was in a hurry. Did I say they were HEAVY.
I use 7 gallon fabric pots in 16” saucers and up on 2” risers. The pots air prune the roots (no roots wrapping around pot) and it’s hard to overwater because they help dry out the soil faster. I’m doing Nature’s Living Soil so I want all nutrients to stay in the pot. Therefore I remove the risers to water, and once the runoff in the saucers wicks back into the pot (usually the next day), I put back the risers to speed up drying out. Watering ended up being veg 2-3 days and flower 3-4 days.
This seems to help manage the correct level of humidity, I do not use a humidifier or dehumidifier at this time. Things may change when the hot weather comes. I do have a small portable air conditioner that might be useful then. We used it in our camping trailer but that’s gone.
Environment: First Grow - Fall and Winter
I started the grow 01 October and quickly found I wasn’t keeping temps and rH where they needed to be when temps plummeted in the middle of the month from the 50s at night to the 30s. I struggled for nearly 2 months to get a working system and my plants were shocked and stunted. I was afraid I would loose them, they looked terrible. All yellow and twisted leaves. By late November things were being dialed in and the plants were starting to look better.
Equipment Setup
My instruments are set to maintain the numbers in this GWE chart.
I keep it on my phone.
AC Infinity T8 fan and carbon filter maintains consistent environment when things get too high. I know that’s not what these fan are designed for but it works awesome and periodically brings in fresh air.
NOTE: this is the OEM controller that came with my fan in September 2020. I’m upgrading to the new Controller 67 for my next grow and will update this section once I have it.
- HT = Veg 86F - Flower 81F
- LT = OFF
- HH = Veg 61% - Flower 51%
- LH = OFF
750w Oil-Filled Radiator with Inkbird Temp Controller Programming the Inkbird 308 VIDEO
- Maintains the normal temperature of the tent.
- These are not great for fast heating of a room, they are best for maintaining heat without drying out the air from a fan constantly blowing.
- Sits in front of the only tent air inlet window I have partially open. This allows the cold air to be heated as it enters the tent.
- Inkbird HT setting Veg 77-80 and Flower 75-77 depending on outside temps.
- Optional: 1500w version
1500w Milkhouse Heater with Inkbird Temp Controller
- Maintains bottom temp and can quickly prevent lows from happening.
- Sits to one side of the radiator in the corner, not facing the plants.
- Inkbird HT setting both Veg and Flower 71-73 depending on outside temps.
- Heater is set to the 1500w setting.
Floor 8” Oscillating Fan
- Sits to one side of the radiator in the other corner.
- Slightly faces up to circulate air from the floor to around the plants and up.
- Blows air around heaters and plants.
Ceiling 6” Clip-On Fan
- Blows heat down into the tent to mix with lower air.
- Keeps hot air from accumulating up high.
8 Outlet Surge Protector with Mechanical Timer
- 4 outlets Always on
- 4 outlets controlled by timer, only SF4000 Light is hooked to this bank.
Control Wall
The two Inkbird sensors, the ACI sensor and the Govee hygrometer all hang banded together above the canopy using a standard ratchet rope hanger so I can raise the height. This maintains a consistent reading for all 4 sensors.
Calibration: All controllers have calibration settings to bring them all to the same temperature number. They should be together when doing this so they are all reading from the same spot in your tent.
Rh is usually not a problem here in the great north-WET, but on occasion when it drops low I either water the plants or place some water in the saucers to evaporate and that puts it right.
This is the control wall. You can see the rope hanger holding all the sensors at top right. I originally had them spread out but found better control with them all together sitting at top the canopy.
In these images, you can see the radiator in front of the intake window, the milkhouse heater to the left of it and the floor fan to the right of it. The milkhouse heater is not facing the plants so as not to dry them out to much. The floor fan oscillates in a 90 degree path, from along the heater wall, across the room and to the back wall. It is angled slightly up to blow the branches and leaves.
The upper fan is straight up from the floor fan and angled to push the air down towards the opposite corners and walls.
Note: after this grow I plan on moving the ACI fan setup to along the opposite wall of the heaters and straight up above the water wand. This was the first piece of equipment I installed upon setting up the tent and I’ve found I would like to expose more of the ceiling poles for the light hangers.
Outside the tent to the right is a 4’ table with a 20 gallon food-grade water barrel with brass spigot, 10’ garden hose and water wand. The hose enters the tent at the bottom through one of the sock openings. It’s gravity fed. Both the spigot and water wand have turn-off valves to prevent accidental flooding. I keep it hung using the cable hanging from an upper sock opening. The ACE brand wand is the best I’ve ever owned. The shower setting with the mild flow of water gets everything evenly wet without washing the soil around. Note: the only negative points in its review were some people cracking the threads in the handle from connecting and disconnecting the hose. I added a brass quick disconnect from ACE to prevent this from happening. Be sure to use plumbers teflon tape on all threads.
Images from my weather app and the Govee hygrometer.
Here they are today, week 7 into flower.
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