New Grow Tent = Unhappy Plant

joeg235

joeg235

Member
I've had to move flowering plants to the garage. Purchased a 4x4x7 grow tent and 400W HPS light. Have a mall fan blowing fresh air in from one of the vent hoods near the floor.
Issues: Temps in garage are in 50 - 60 range (until summer).
Using a small space heater - can only keeps temps in the high 60's (day)
Run light at night -
Plant is not liking this - some heat stress.

Questions:
1. Suggestions for other heat sources? Would a small oil-heater work better? I'm guessing all the hot air is bad for the plant. Or an electric blanket in the bottom of the tent? Or electric floor heat mat?

2. When summer comes (soon) I'm guessing daytime temps (no light) can go about 80 (or higher). Will I need to plan to exhaust the air? Possibly just exhaust the heat from the light? I was going to get a second 400W light (to accommodate 4-6 plants) but now thinking an investment in decent reflector + exhaust system for light will keep it cool enough (lights 9pm to 9 am) and allow the light closer to the plants. I still plan to run a fan to bring cool air into the tent.
Or, can I simply draw air from the tent via the light and its exhaust? (i.e. not a "closed' system) Or does the light exhaust have to be a "closed" system (in from one vent out via the other).
 
meetzu

meetzu

Well-Known Member
Are your plant's sitting on a cold floor? I wouldnt put anything electric actually touching the ground. I have nothing that uses electricity on the ground just for safety sake (water). You could buy styrofoam sheets and use those to insulate the bottoms of your plants if they are indeed on a cold floor and you think that could be causing the problems.
 
joeg235

joeg235

Member
not directly on the cold floor - there are two layers of tent materials between the pot the plant is in and the floor. I could add styrofoam, but I think soil temp is not the real issue.
The issue is the ambient tent air can drop below 60 AND we have high humidity (>50%) so mold becomes a factor.
I'm pretty sure I need to heat the tent -= at least till summer.

Looking for suggestions on how best to heat it.
 
Ian Singerdale

Ian Singerdale

Well-Known Member
joeg235 said:
I've had to move flowering plants to the garage. Purchased a 4x4x7 grow tent and 400W HPS light. Have a mall fan blowing fresh air in from one of the vent hoods near the floor.
Issues: Temps in garage are in 50 - 60 range (until summer).
Using a small space heater - can only keeps temps in the high 60's (day)
Run light at night -
Plant is not liking this - some heat stress.

Questions:
1. Suggestions for other heat sources? Would a small oil-heater work better? I'm guessing all the hot air is bad for the plant. Or an electric blanket in the bottom of the tent? Or electric floor heat mat?

2. When summer comes (soon) I'm guessing daytime temps (no light) can go about 80 (or higher). Will I need to plan to exhaust the air? Possibly just exhaust the heat from the light? I was going to get a second 400W light (to accommodate 4-6 plants) but now thinking an investment in decent reflector + exhaust system for light will keep it cool enough (lights 9pm to 9 am) and allow the light closer to the plants. I still plan to run a fan to bring cool air into the tent.
Or, can I simply draw air from the tent via the light and its exhaust? (i.e. not a "closed' system) Or does the light exhaust have to be a "closed" system (in from one vent out via the other).
Click to expand...
well problem number one is that you are using a space heater at all. 400W HPS can give off a massive amount of heat already. Have you actually measured the temps in the cab while the light is on? if it's 40 degrees outside the cab should be like a perfect 75 degrees in there. I bet it's just too hot for them.

Second of all, go and buy a decent inline duct fan asap. They are suffocating, they need constant air exchange. the heater is just making it much worse. If you use ANY heater at ALL (only if cab temps drop below 65 during lights on) make sure it is electric ONLY.

you will need at least 150 - 250 cfm (cubic feet per minute) fan running constantly. the more cfm the better, especially if it gets to 80 ambient in the garage.

honestly though, if it gets that high temp in your garage and you can't get AC in there, I'd say fuck it or grow somewhere else. No matter how good of a fan you get

80 degree air temps plus 400W HPS = over 100 F

you are going to cook them alive
 
joeg235

joeg235

Member
You make very good points - thank you for stopping and helping.

Right now I run the lights by themselves at night (no heater) and I think the temps are fine ( will measure and check again. I have my temp probe in amongst the branches of the plant.)

The issue is when the light is NOT on. I run lights 9pm - 9am. During the day (9am - 9pm) the temps can be in the mid 60's or lower right now.

I am mostly using the space heater during the day. I realize I will have to vent during the summer (and am planning on that now).

I am wondering what to do now during the day while the light is not on.
 
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