So the time has finally come and you’ve decided on fulfilling that dream it seems you’ve had forever of growing your own cannabis plants. You went to your local growers supply store and purchased things like a grow tent, grow lights, extractor fans, and even a special air conditioner and humidifier so you can fine-tune the space to have the ideal temperature and relative humidity of your space. Now that you’re at this juncture you’re now probably asking yourself, when growing marijuana just what is the ideal grow room temperature?
How does the temperature of the grow room affect the plants?
It’s no secret that having the right temperature when growing cannabis is vital for your plant to undergo photosynthesis correctly and at the least stay alive. If you don’t provide enough heat and the temperature in your grow room is too low, it will stunt the growth of your cannabis plants as it will lessen the evaporation through the leaves and cause the suction force to shrink, which affect how nutrients are consumed by the roots. In this scenario the nutrients that aren’t consumed will stay in the growing medium and over time dissolve in the root system. This will create highly acidic environment that will stunt the growth of your marijuana plants.
On the other hand, high temperatures that are above optimal will increase the risk for pests like spider mites and diseases like powdery mildew and root rot. This is because these pests and bacteria thrive at higher temperatures and coupled with high humidity can set the stage for a troublesome ordeal that can cause nightmares to cannabis growers both experienced and novice.
What may have started off as something that did not seem like a big deal could become a major problem in multiple areas of the plant which can only produce those terpene-rich buds your seeking if they are all functioning correctly in unison. With that being said, it is necessary to have the right temperatures in your growing space so that none of these processes are thrown off. So, let’s go into more detail about the best temperature and how to properly control the environment.
Does marijuana grow room temperature influence the potency of the plant?
From the vegetation stage all the way into the flower stage, growing cannabis is not a “set it, and forget it” ordeal. If you want terpene-filled buds teeming with trichomes covered in THC and other cannabinoids it is vital that you educate yourself and get the proper equipment to ensure your indoor grow room is at the optimal temperature. If things such as air circulation and humidity levels are neglected as well it’s safe to say your grow will turn out less exciting than you expected.
What is the ideal temperature range for a grow room?
There are many things that determine the overall temperature in your indoor marijuana grow room. You might not have thought about it, but exactly where your grow room is situated in the home is critical. For instance, have you ever noticed how much cooler it is in the basement than it is in the attic? Also, room size, air flow, how many grow lights you have and how good the rate of air extraction is are important. You will need to consider these factors when creating a grow room.
When the grow light is on, the best temperature to promote plant growth for seedlings and cuttings is from 68°F to 77°F. Once your plants mature, they can handle even more and the temperature could rise to as much as 82°F. If the light is off, the temperature needs to be kept at around 62°F to 72°F. One other critical point is that the temperature changes between day and night and can never be too high. When the temperature is 82°F in the daytime, it should never drop below 64°F at night.
Measuring the temperature
The temperature in your room should be measured with a thermometer. You can find both digital and analog thermometers either online, your local gardening store, and if you’re looking for something fancy your local indoor growing specialty store should offer top of the line solutions. To monitor temperature and humidity in grow rooms, thermostat / hygrometers have been developed over the past few decades. Thanks to their sensors, these devices give information about humidity and air temperature in your growing area. With a practical display, they provide a clearly legible indication of the measured values at all times and even work in Celsius and Fahrenheit. Try to at least get a thermometer that has a temperature sensor on a wire, so that way you can hang the display outside of the grow room and you can easily monitor the temperature when the lights are off.
Remember only to measure the temperature in a shaded area and different parts of the grow room. Put a few fans in the room for good air flow as this will also help in maintaining optimal temperatures in the entire room. Lamps will not change the air temperature, but it will usually be a little warmer under the lamp than it is in the shaded areas. This is nothing to worry about, just be sure there is enough space between the lamp and the plant. You do not want the tips of the plant to get burned. The lamp heat will influence the room temperature unless you are using LED lights.
How to lower the temperature
More often than not, much heat can easily become an issue in the grow room. Most of the popular lamps used to grow create so much heat! With fluorescent lights, it is not so much of an issue. However, HPS lamps may raise the temperature to extreme levels of 122°F, which could kill your plants! You have to understand the range of the grow room. With 600-watt HPS lamps, use a space no less than 3.2 ft. x 3.2 ft. x 6.5 ft. to avoid these issues.
To extract heat, use this easy method; the amount of watts divided by two = extractor in cubic meters (feet). So, 2 x 600 watt HPS needs an extractor fan of 600 m3. Extractor fans blow the hot air out of an area and bring in fresh air. You can even add a carbon filter to ensure the marijuana smell doesn’t go out of your room. Using ballasts placed outside of your grow room also creates plenty of heat, so check to make sure that the warm air outside doesn’t affect the degrees Fahrenheit inside the grow room.
The simplest way to make sure the temperature remains low is to keep the extractor fans on at night. The lamps will come on for a few hours once the sun sets and go off a couple of hours after the sun comes up. Doing it this way keeps the lights on during the cooler parts of the day. Some experienced growers will also use an air conditioning unit for lower temperatures in order to run it throughout the day and night.
Raising the temperature
You do not have to raise the temperature if the lights are on. The lamps will do that on their own. It is critical that the air is moved throughout the grow room equally so that you have the same temperature all over and minimize potential heat stress. You can get swivel fans for this purpose and face them between the lamps and the plant. Any fresh air from outside needs to be moved throughout the space so there are no cold spots. This is definitely the case in the winter when the temperatures fall below freezing in some parts of the world.
It can also become cold in the room when the lights are off. To raise the temperature it’s ok to use something like your old space heater with thermostat to heat up your grow room. Just keep in mind that they use a lot of electricity. Also, radiators with thermostats are good as well. You can even turn off the extractor fan when the lights turn off. You can do this with a fan controller that has a thermostat, or a timer.
Managing airflow and humidity levels
This simply wouldn’t be a comprehensive guide if we did not to talk about humidity (the amount of water vapor in the air). Temperature and relative humidity are intertwined and produce different effects when one, or both, are too high or low.
The optimal relative humidity is around 40-60% humidity in the grow room. Staying closer to the lower end is important during the flowering stage. Grow room temperature and humidity must be controlled together for optimal cannabis production. As previously mentioned too high of humidity can create a breeding ground for pests and bacteria which can kill your plants in the link of an eye. When you have lower humidity and your plants will not only be stunted in their growth but they will begin to show symptoms similar to that of a plant that isn’t watered enough such as a wilting and nutrient burn.
Want to learn more?
Educating yourself as much as possible on the subject of growing cannabis as well as indoor grow rooms will only further improve your chances of a successful grow. A free and easy way to get started is to search for more articles on the subject of growing here at grasscity.com which are written by reliable sources who know a thing or two about growing. If you’re looking for a book you can order, look no further! our forums are filled with helpful info and users feedback on a wide variety of texts on the subject, including the best place to buy them. Click Here to learn more.