Growing Organic Cannabis: Part 12 Environment


Growing Organic Cannabis: Part 12

( Photo Credit: u/savemesomeforlater, Red Hot Cookies )


Cannabis is like every other plant, it has a sweet spot for environmental factors where it grows like crazy.

Several factors go into the environment, the first being the soil, the second being the water, but there are also factors like temperature, humidity, air-flow and light intensity to consider as well.

If you remember nothing else from this article, remember these two figures that Cannabis prefers:1. Cannabis likes temps from 70-85 F, outside that range growth/bloom can be affected if it is not a hardy strain.2. Cannabis likes RH, Relative Humidity, in the range from 50-60% for pretty much its whole lifespan.

There are several pieces of equipment that can help you with environmental controls that won't break the bank. I'll list those pieces of equipment at the end of the article.


Cannabis prefers temperature ranges from 75 to 85 for vigorous growth, some varieties from the highlands of the Himalayas are very resistant to cold temperatures, and certain other In-Bred Lines like ErdPurt are also extremely resilient to the cold. There are a few strains that have adapted themselves to very hot, arid climates from places like Afghanistan and Egypt. But mostly Cannabis likes that cool spring like weather that is not too hot or too cold. Too hot and the plant can't pull enough water through itself to keep itself cool and it wilts and dies. Too cold and the flow of nutrients through the plant slows to a crawl and so does growth, and if the plant freezes, the formation of ice particles inside the plants tissues will certainly kill it.

If you are like me and grow indoors, you can adjust your light and dark periods to line up with the parts of the day that give you the best temperatures you can create. I run my lights at night in both summer and winter: in the winter it keeps the plants from getting too cold, and in the summertime, I'm not cooking them by running the lamps during the hottest part of the day.

Of course if you growing in the middle of winter and there is a blizzard outside, you might need to use your household heating system to raise the temps -- but you can protect your plants from sudden temp dips by placing an electric heating pad underneath the run off tray, this will keep roots warm.
And if you are growing in the middle of a hot muggy summer, you will probably need to bring air conditioning into the situation somehow. You can grow plants in the heat, but their buds will be loose, low density, their quality will suffer, so do what you can to control temperatures and keep that optimum range going.


Cannabis has a preferred humidity range that is relative to its current stage of life. Seedlings prefer a lot of humidity, like between 60-70% Relative Humidity (RH). Vegetative plants are okay with a little bit less humidity, generally being happy between 45 and 55 humidity. And during flowering stage... well there is an ongoing argument in the community about the exact RH that is perfect for plants, there isn't a full consensus yet, but the general theory is between 55 and 65 RH for flowering.

If humidity goes above 70% and stays there you are risking the formation of powdery mildew, mold, bud-rot (botrytis) and other unpleasant plant diseases. If humidity goes below 45% this puts a strain on the plants transpiration process forcing it to drink excessive amounts of water to compensate for the dry environment. Also, apparently spider-mites and other bugs seem to prefer hot and dry climates.

Air Flow

Plants breathe CO2 and exhale O2. Just like with fish in an aquarium, if you have your plants enclosed in a space with poor airflow, you could be smothering them a bit and hurting your end yields.
If you use a carbon canister filter, make sure that the filter is not clogged and has good airflow. If you use a tent, maybe remove one or two of the ventilation patches to increase airflow.

I bought a pair of cheap clip on desk fans for each of my grow tents. They work great to keep the air circulating.

Good airflow can also help temperature control, and if your plants are subjected to a constant breeze they will develop strong branches that will be able to hold heavier yields.

Light Intensity

Plants need the right amount of intensity of light for the stage they are in.

Seedlings are delicate, fragile creatures, you don't want to blast them with 1000W bloom lamps, but if you have nothing else, then make sure the lamp is raised to the max and your seedlings are lowered to the max.

During vegetative growth phase, you can lower the lights within 12-18 inches of the tops of the plants. A good minimal pruning that selectively culls large fans that would obscure the light source for budding sights below helps to maintain maximum light penetration into your canopy as well.

If you notice your plants stretching or getting really lanky and your lamp is more than 20 inches away, the plants are probably stretching towards the light because they want more of it. Move the light a bit closer to plants that look like they are stretching a bit, or raise the plants up closer to the lamp. Stretching is bad as it creates weak points in the stems that will inevitably fail.

( Photo Credit: u/MiniEggsQuattro, unknown strain )


There are some handy tools that will help you grow great weed that won't cost you too much money. Depending on the climate where you live and whether you are growing indoor or outdoor, you can often pull a decent crop on a very frugal budget, especially outdoors. But sometimes the low-cost solutions aren't effective enough and you gotta pull out the big guns (like using air conditioning, or buying upgraded grow lights) to get a top-shelf-quality harvest.

  • Temperature control: Fans are really good, really cheap way to increase air-flow, and to curb the higher ranges of the temperatures. Also, you can change up the time the indoor lights kick on. I keep my timers set for nighttime to keep my heating/cooling costs low -- and my electric bill low too -- middle of the night is "non-peak" hours for electrical billing. Of course if you live in a very hot or very cold climate, you may need to rely on your house heating/air-conditioning systems to help you control temperature.

  • Humidity control: There are very inexpensive humidifiers that work as advertised, I use small desktop sized units for my grow tents since my space is limited and anything larger than that would be absolute overkill and fog out my tents with like 95% humidity. I have to keep the small desk-sized units set to low inside my tents, or even they are too much humidifier in too tiny of a space. If too much moisture is your problem, then there are dehumidifiers that will pull atmospheric moisture out of the air and reduce the RH -- note: these units collect pure water which can be used for watering, and their catch-basin will need to be emptied regularly or they will shut off.

  • Air Flow: Fans work great, so does carbon-filtration systems. I've never needed to inject CO2 into my growspace, just a fan in there blowing air around and the ventilation ducts opened up is enough to keep the air from getting "stale". There is another side benefit to using fans -- in nature if a tree is protected from wind, its branches will be so weak that it will break under its own weight as it gets older, more massive. The same is true for Cannabis -- small, gentle, but constant, agitation with a fan will strengthen your branches so that later when they are blooming they won't break under the weight of their own resins.

In part 13 of this series we'll discuss growing techniques!

If you liked this post, then hit that upvote button! Subscribe and follow, and if you're feeling chatty, drop me a line in the comments.

Until then, happy toking ya bunch of potheads!

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