Growing INDOORS has some basic principals that should be considered no matter what the design (tent, room, attic, garage, basement, even in a window).

Most setups with grow lights will require that you vent out hot air using a fan and/or an exhaust system. If you’re worried about the smell of cannabis, make sure any air being vented outside grow room/house gets filtered to remove the scent of cannabis. For example, many growers choose to get a carbon scrubber to “scrub” all odors before the hot air is blown outside. By creating good suction with an efficient exhaust system and adding a carbon scrubber, you can basically eliminate all smells from the grow room, inside and outside of the grow area.

When the humidity is too low (air is dry), it’s important to make sure you provide plenty of fresh water to your plants at all times. You may need to reduce the amount of nutrients you’re providing as the plants will drink more water and therefore absorb more nutrients through their roots than when the humidity is not as dry.

When it comes to controlling humidity indoors, you may need to use a humidifier and/or a dehumidifier to keep the humidity in the optimal range. A humidifier adds moisture to the air while a dehumidifier takes moisture out.

Controlling your grow room humidity is one of the tricks that separates the expert growers from the beginners.

You can get some pretty fancy humidity gauges to place in your grow room, and products to help change the humidity are commonly found at department stores, hardware stores, or most stores that sell home appliances. There are also some DIY options discussed in our complete article about controlling indoor humidity.

Here’s the most important things to keep in mind when it comes to the humidity of your cannabis grow room.

  • Ideally, your grow room will have a humidity of 60%-70% during the vegetative stage, and should be lowered to below 45% during the flowering stage.
  • As your buds fatten up, it is beneficial to continue to drop the humidity of the grow area, if you can, to increase resin production and cause your plant to product more terpenes (the stuff that makes your buds smell great), though lowering the humidity too low can increase the chance of your plant running into problems.
  • During the last 2-3 weeks before harvest, use of a dehumidifier to dramatically drop the humidity of my grow area as low as possible to help prevents bud rot during the last few weeks.
  • As an added bonus, dropping the humidity this way during the last few weeks of your plant’s life increases trichome production, so you harvest sparkly, crystal-covered extra-potent buds.

With the right tools, the task of maintaining humidity can be close to automated, and you will see huge benefits compared to the amount of time and money you invest.

When the air feels moist or humid (or a humidity monitor alerts you to high humidity), it’s extra important to ensure that plants get plenty of air circulation and have lots of air movement. You also want to avoid letting leaves touch each other during periods of high humidity. You can fix constantly too-humid conditions with an exhaust system, fans, and possibly a dehumidifier.

When the air is too dry indoors, you can either choose to let your plants grow hardened to the arid air, or you can use something like a “swamp cooler” to add humidity while also reducing the temperature of your room.

An oscillating fan will circulate air in the room as well as provide a gentle breeze for your plants, reducing hot spots from forming