Best Grow Room Temperature For Growing Weed

What is the best grow room temperature for growing weed? Temperature control is important for growing marijuana but so is knowing where to take it.

My grows have always done OK but my temperatures always seemed to be on the high end of things. I use air cooled hoods and fans but because my grow area is small I would sometimes get readings in the 90s. That is just fine if you are running  CO2, but not good for a standard grow.

Since yields were decent I really wasn’t too concerned, but things change. I am now growing some Hells Angel OG and will likely be growing some other OGs and these girls like cool temperatures. Also since OG strains are not known for their high yields to start with, it becomes even more important to dial in the grow room.

Grow Room Temperature Affects Yield And Quality

High temperatures during flowering can affect bud density, potency and smell and reduce yield. Low temperatures will result in slower plant growth, reduced nutrient absorption and you guessed it, lower yields. To get top yields it is important to dial everything in. A grow room that gets out of wack whether it is from temperature or humidity will never produce top yields.

Also if you grow hydroponically your water temperatures are very important and the temperature of your grow room will affect this. Too high a water temperature will result in less oxygenation, poor nutrient absorption and can lead to root rot.

Wide swings between day and night temperatures will promote internodal stretching. So keeping temperature a few degrees cooler at night than during lights on can be used to help control plant size.

What Is The Best Temperature For Growing Weed?

I have always heard the best grow room temperature is 80 to 82 degrees and you should take temperature at canopy level, but this can be misleading because you really want to measure room temperature and not radiant temperature. Surfaces will absorb radiant heat from the lights and be warmer than actual room temperature.

If the room feels comfortable to you it is probably OK for your plants too. Leaves under your lights will be warmer than air temperature because of radiant heat from the lights. That is OK because they are designed to absorb energy from the sun they can handle more heat.

The problem is that when we try to take temps under the lights our thermometers, digital or otherwise will give false readings because they are absorbing heat. So if you do take temperatures here you need to shade the thermometer.

I started hanging mine between my two reflectors just below the top of the glass and my readings are now totally different. I figured that heat rises so placing the thermometer higher up would give a better reading of my grow room temps. My thermometer is now above the canopy, between it and the glass and for the most part shaded. I now get readings in  the 78 to 82 degree range which is just about perfect.

Grow Room Temperature Control For Top Yields

Want to get 2 pounds per light? Top grower tells you how in this video. It’s all about  grow room temperature and humidity control.

It is interesting that this grower says it really doesn’t matter what nutes you use if you control your growing environment. I haven’t really touched on humidity control in this article, but it is equally important to getting top yields. If plants can’t breathe right they wont be happy and won’t give you the yields you want.

So the greatest yield increase will come from proper grow room design and grow room setup and not from some overpriced, over hyped bottle of nutrients.