Cannabis is a tropical plant, which means that it’s sensitive to heat, and temperatures that are too low or too high can kill or seriously hurt your harvest. Cannabis likes to grow between 67 and 78 degrees Fahrenheit, on average. Basically, if it’s comfortable for you, it’s comfortable for your plants. However, cannabis plants need bright light, and that comes with heat control issues if you’re growing inside. If you’re growing cannabis indoors, your grow room setup is key to helping you control heat.
Be Aware of Light Heat
Your lights are going to be the main source of heat for any indoor grow operation. When choosing your lights, remember that the right grow lights can make or break your grow room setup. There are tons of lights out there to choose from, so do some research before you buy anything.
The cooler your grow lights run, the less work you’ll have to do to keep your grow room at a safe temperature for your plants. Some lights, especially HPS and MH grow lights, throw off a lot of heat for the intensity of light they produce. Others, like fluorescent and LED lights, can be much cooler. Cooler lights tend to be more expensive up front, but they have significantly longer lifespans and save you money elsewhere.
For example, LED grow lights may cost a little more up front to set up, but they last three times as long as an HPS grow light. LEDs also don’t heat up nearly as much as HID lights, only reaching about 107 degrees Fahrenheit, compared to HID lights that can reach 200+ degrees. It’s simpler to spend the money on LEDs than an entire extra cooling unit for your grow tent.
Step Up the Ventilation
No matter what, you’ll need to have ventilation to control heat while growing cannabis. Even the coolest lights still run twenty to thirty degrees above what cannabis plants prefer. In an enclosed environment, things can heat up quickly. This can cook your plants, and it’s why ventilation to remove heat from your grow tent is very important.
Even the smallest tent should have at least one fan. Six inches is the preferred minimum size. This keeps the air moving throughout your grow area, and ensures that the temperature is consistent throughout the room. It also prevents diseases like powdery mildew that thrive in still environments.
You should also have an exhaust fan, one that pulls hot air out of your grow room and pulls in fresh cool air from somewhere else. Ideally, the exhaust fan should be rated for the volume of your room. For example, in a room 10 feet wide by 10 feet deep by 10 feet tall, your exhaust fan should be able to handle 1000 cubic feet per minute. You might consider looking for one with a carbon filter if you’re worried about the smell.
Install Some A/C
If ventilation isn’t enough to keep temperatures down in your grow room, you can look into portable air conditioners. These units will pump cool air directly into the room and help keep temperatures reasonable. The thing to keep in mind with an AC unit is that they generate heat that must be vented. Direct the vented heat away from where your ventilation system takes in cool air, because otherwise you’re just making the problem worse.
Heat is important to keep your plants healthy, but too much is definitely bad for your crop. If you choose your lights, ventilation, and AC well, you can keep your temperature under control. By keeping a watchful eye on your grow room temperatures, you can have a safe, healthy crop without heat stress, and your harvest results will be better for it.