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No matter how well-equipped or thoughtfully laid-out your grow room may be, it’s important to remember that plants are plants and you need to be careful about the sort of environment they’re growing in.

This includes lighting, proper air cycling, and perhaps most importantly, temperature management. For a good part of the year, most of the country faces weather that doesn’t exactly contribute to plant growth, and even if your plants are growing indoors you still need to keep them insulated from the cold or sheltered from the extreme heat. Knowing how to control the temperature in your grow room will go a long way towards keeping your plants healthy and productive, even if it’s roasting or freezing outside.


The first thing you should look into is finding out what temperature your plants need. The majority of indoor plants should be kept between 70 °F and 80 °F during the day, and 65 °F to 70 °F at night, although this may vary for certain varieties or strains of plant life, so further research may be required on your part. Even if you’re not working with a ton of space in your grow room, it’ll be worth installing some separate thermometers both inside and outside the grow room so you can keep a close eye on its current temperature and make adjustments as needed.


After establishing a safe temperature for your plants, you’ll then need to ensure proper ventilation in your grow room. If you have central air and/or central heat in your house, it may require a bit of a balancing act – you don’t want any of your plants close enough to the vents to dry them out, but you also don’t want to block airflow. Move your grow room shelving around to ensure better airflow, and make sure nothing is taking the full brunt of the vent when the heat kicks on.

Similar to ventilation, you’ll also want to regulate the temperature on any incoming air. If your grow room has a ventilation system of any kind, from a fancy intake setup to a simple box fan pointed back out into the hallway, make sure there’s not any drastic temperature differences between the grow room and the room behind it, as this can prove detrimental to the health of your plants over time.


Even if the thermometer is cooperating, there’s still the chance of external factors affecting your temperature, such as proper placement of lights. If you use grow lights or overhead LED lights in your grow room, you’ll need to make sure your plants aren’t too close to the lights, as this can cause temperature fluctuations and may dry them out prematurely. Check your taller shelves or greenhouse pan racks to make sure they’re not close enough to get affected by any lights or any change in temperature near the ceiling. (This also applies to drying racks, as you don’t want your plants to be too dry.)


Finally, you also need to remember to keep an eye on the humidity of the room. No matter what the weather is like inside or outside your grow room, relative humidity (RH) is a crucial factor. Plants growing in an environment where the air is hot and dry will tend to have much slower, stretched growth, whereas cool and overly humid rooms will tend to restrict a plant’s growth and can encourage the development of mold or fungus.

With all of these tips in mind, you can manipulate the environment of your grow room to encourage better, more healthy plants no matter what time of year it is.

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