Growing Weed: Creating the Environment Your Cannabis Plants Crave

By Cory Hughes
Published: February 21, 2018 | Last updated: April 23, 2021 12:02:36
Key Takeaways

​Environmental control in the growroom can drive you crazy if you let it. It is simple in theory, yet it can be difficult in practice. Balancing the factors that create a formidable environment can, at times, make you want to give up, but hang in there. Examining your environment and taking a simple, analytical approach to solving problems is the most effective way to provide high-quality cannabis indoors.

So, the time has come. You’ve waited for this your whole life, and now it’s finally here. Cannabis is legal and you want to get to work setting up your own indoor grow. While anyone can drop a clone into some grow media and hope for the best, to grow the best-quality plants and maximize your yields, you really need to focus on the basics. This includes figuring out how to maintain a proper indoor environment. Achieving and maintaining the optimal growing environment is, in my opinion, the single most important factor in producing quality cannabis.


Maintaining the optimal grow room environment simply means putting processes in place to deal with all the outside factors that interact with your plants and have the potential to shape their growth, or lack thereof. A grow room’s environment includes more factors than just dialing in your temperature and humidity levels, but this is where growers should start. If you can maintain proper temperatures and moisture levels, you will save yourself a slew of problems with pests and diseases.

The Right Temperatures for Indoor Cannabis

Cannabis plants thrive in temperatures around 67-78°F. Sounds easy enough, right? Just set the AC and forget it? Not so fast! The temperatures and humidity levels in your grow are affected by numerous factors, which can, at times, make you feel like you are constantly juggling things that are out of your control.


Your light system is a major player when it comes to affecting the heat in your room. For years, cannabis growers have been using grow lights with built-in ducting for HVAC, which was required to cool the bulbs. Large HVAC units blowing through your lights is a great idea in theory, but depending on where the air is coming from, you could be contaminating your entire grow with pests. If the HVAC pulls air from outside, you will not only be sucking in the outside air, you’ll also be sucking in mites, mildews and more.

The alternative to complex, HVAC-vented lighting systems is to go with a cool-running LED, or plasma system, or a double-ended, compact system that uses HPS bulbs. The majority of double-ended lighting systems are designed around the concept of no direct cooling through venting. They typically have a smaller frame, and removing the cooling system from the equation allows the lights to be hung higher, which provides more space between the light and the plant canopy. The great thing about raising the lights is that you get more plant coverage per light than you do with a vented system. The downside is that your room’s AC needs will increase dramatically, which will cost you. Luckily, to better manage everything, there are a ton of plug-and-play tools to help you monitor everything from your phone while you are on the go.

The Right Humidity Levels for Indoor Cannabis

Humidity refers to the amount of water in the air and can be tricky to master. You want to maintain a humidity level of around 40-50% during the flowering stage, while your clones and veg plants should start at around 70% humidity and drop over time. The biggest factor affecting your grow room’s humidity levels is where you live.


While indoor grows are supposed to be isolated from the outside, there is no escaping the effect varying outdoor temperatures have on the indoor environment. Whether it’s due to leaky doors or windows, a drip in the roof or a myriad of other factors, outside air can always creep its way indoors.

If you live in a desert-like climate, you are going to need a swamp cooler. Of course, there are other cheap ways to increase humidity levels if you stay diligent. Leaving one or more buckets of water around is probably the easiest and cheapest method. If you are more into the mechanical stuff, a swamp cooler is probably your best bet.


If your humidity levels are too high, you are—beyond a shadow of a doubt—going to run into pest and mold problems. In higher humidity grows, powdery mildew becomes prevalent if you’re not careful, as do spider mites, which flourish in hot, wet environments. If you are having a hard time maintaining your growroom’s humidity levels, it’s worth it to invest in a high-end maintenance and monitoring system.

No matter what it takes, you need to shield your indoor environment from the outside as best you can. If this means fixing that leak in the roof, it means fixing that leak in the roof. And if it all leads to healthy plants at the end of the day, it will all have been worth it.


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Written by Cory Hughes | Commercial Grower

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Cory Hughes is a former police officer turned full-time commercial grower in Denver, Colorado.

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