What’s the Best Grow Room Temperature and Humidity Level?

Ideal grow room humidity and temperature varies depending on the phase of plant life. Cloning requires higher humidity and temperature than vegetative growth and flowering plants have different ideal atmospheric conditions too. In order to master the craft of marijuana growing, dialing in the proper environment at the ideal time remains the most essential ingredient for success. So, what is the best grow room temperature and humidity level?

In order to properly measure temperature and humidity, you’ll need a thermometer and hygrometer. Better to invest in a digital one that can give you current readouts as well as highs and lows when you’re not within the room. These may be outside or inside the growing space based on the size of your area and how much the temps and moisture levels fluctuate. A humidifier and a dehumidifier may be employed to raise and lower humidity prices. Larger grow rooms may benefit from a controller that uses a sensor to keep tabs on temps and humidity and turns on the appropriate appliance to regulate and maintain them within your set parameters.


Since cannabis cuttings root best in warm conditions with high humidity, the affordable trays with clear plastic domes work remarkably well.  In cool conditions, a heat mat should be placed underneath the trays to maintain an optimum temperature of 74-78 degrees F. and relative humidity at 75-85%.  No matter where and to what medium you intend to root your clones, maintain heat and higher humidity on your priority list. Clones allowed to get dry or cold will perish quite quickly. Too much humidity (over 90%) may also lead to mold and rot, so cut a quarter-sized hole or two in your clear plastic dome to allow some air movement and flow.

The Vegetative Stage: Greatest Grow Room Temperature

The best grow room temperature during the vegetative stage of growth is 70-78 degrees F. when the lights are on during the “daytime” and no longer than 10-15 degrees cooler at “night” with a relative humidity of 45-55%. With these settings, your plants will be able to convert light into energy for growth. This is the time when the plant puts on branches and leaves and expands it’s root system during your growing medium. If it gets too cold or hot, growth ceases and you eventually risk losing your plants altogether.

The Flowering Stage: Greatest Grow Room Temperature

The best grow room temperature during the flowering period of growth is 68-75 degrees during the day and no longer than 10-15 degrees cooler at night. If you’re supplementing with CO2, daytime temps are often as large as 75-82 or so. During flowering, you should lower your relative humidity to 35-45percent and even lower (30%) for the last few weeks before harvest. This will help you avoid issues with mould, bud rot and PM (Powdery Mildew) that could arise in higher humidity.

The drying room is a place that must be carefully monitored. Bear in mind that your plants will be giving off a large quantity of moisture to the room as they dry. It’s important to pull wet air out and keep air circulating in the room without really having fans blowing right on your hanging branches, which may dry them out prematurely leading to a harsh taste and burn. Also, growers in dry areas like Colorado struggle to expand their drying time with humidifiers, while farmers in more humid climates like Northern California use dehumidifiers to pull water from the air to be able to avoid mold growing on their buds.

The ideal temperature for a drying room is between 65 — 74 degrees Fahrenheit and humidity between 45 — 55% in a dark well-ventilated room. Cannabinoids, terpenes, and flavonoids can vanish and be released at temperatures over 80 degrees, decreasing the odor, flavor and potency of your buds. Within 6 — 10 times your branches should snap rather than bending and the buds should feel popcorn tender on the outside. This is the time to lower the person buds out of the branches and put them into glass jars to start the curing process. Heal your buds in a cool (68-72 degree F.) and dark place.

Released at Mon, 28 May 2018 16:30:38 +0000

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