Ideal grow room temperature and humidity varies depending on the stage of plant life. Cloning requires higher temperature and humidity than vegetative growth and flowering plants have different ideal atmospheric conditions as well. In order to master the art of marijuana growing, dialing in the proper environment at the right time remains the most essential ingredient for success. So, what is the best grow room temperature and humidity level?
Measuring and Changing Temperature and Humidity
In order to properly measure temperature and humidity, you’ll need a thermometer and hygrometer. Best to invest in a digital one that can give you current readouts as well as highs and lows when you’re not inside the room. To raise heat, you’ll need a heater and to lower heat, you’ll need an air conditioner. These can be outside or inside the growing space depending on the size of your space and how much the temps and moisture levels fluctuate. A humidifier and a dehumidifier can be employed to raise and lower humidity rates. Larger grow rooms can benefit from a controller that uses a sensor to keep track of temps and humidity and turns on the appropriate appliance to regulate and keep them within your set parameters.
Cloning
Because cannabis cuttings root best in warm conditions with high humidity, the cheap 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 into what medium you plan to root your clones, keep warmth and high humidity on your priority list. Clones allowed to get cold or dry will perish quite quickly. Too much humidity (over 90%) can also cause mold and rot, so cut a quarter-sized hole or two in your clear plastic dome to allow some air movement and circulation.
The Vegetative Stage: Best 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 more than 10-15 degrees cooler at “night” with a relative humidity of 45-55%. With these settings, your plants will best be able to convert light into energy for growth. This is the time when the plant puts on leaves and branches and expands it’s root system throughout your growing medium. If it gets too cold or hot, growth stops and you eventually risk losing your plants altogether.
The Flowering Stage: Best Grow Room Temperature
The best grow room temperature during the flowering stage of growth is 68-75 degrees during the day and no more than 10-15 degrees cooler at night. If you’re supplementing with CO2, daytime temps can be as high as 75-82 or so. During flowering, you should lower your relative humidity to 35-45% and even lower (30%) for the last couple of weeks before harvest. This will help you avoid issues with mold, bud rot and PM (Powdery Mildew) that can arise in higher humidity.
Drying and Curing
The drying room is a place that must be carefully monitored. Keep in mind that your plants will be giving off a large amount of moisture into the room as they dry. It’s important to pull wet air out and keep air circulating in the room without actually having fans blowing right on your hanging branches, which can dry them out prematurely resulting in a harsh taste and burn. Also, growers in dry places such as Colorado struggle to extend their drying time with humidifiers, while farmers in more humid climates such as Northern California use dehumidifiers to pull water from the air in order 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 percent in a dark well-ventilated room. Cannabinoids, terpenes, and flavonoids can evaporate and be released at temperatures above 80 degrees, diminishing the scent, flavor and potency of your buds. Within 6 – 10 days your branches should snap instead of bending and the buds should feel popcorn dry on the outside. This is the time to cut the individual buds from the branches and put them into glass jars to begin the curing process. Cure your buds in a cool (68-72 degree F.) and dark place.
FAQs
The best temperature and humidity for a grow room depend on the stage of growth. For seedlings: 75-85%% humidity, 70–85°F day temperature, and 65–80°F night temperature. For vegetation: 45-55% humidity, 70–85°F day temperature, and 60-75°F night temperature.
What is the ideal temperature and humidity for plants? ›
Temperature, Humidity and Other Important Factors
There are typically three main temperature points of plant growth. These refer to the minimal, optimal, and maximum temperature. Vegetative phase – 25 degrees Celsius and 60-70% humidity. Flowering phase – 28 degrees Celsius and 40-50% humidity.
Is 60% humidity too high for flowering? ›
Nearly three-fourths (73%) of respondents said the optimal humidity level in flowering rooms is in the range of 40% to 55%. Eighteen percent said 56% to 65%. While 3% of cultivators said that their ideal flower-room humidity level is in the range of 76% to 80%, none said that above 80% humidity was ideal.
What is the best Rh for flowering? ›
The ideal cannabis flowering humidity is between 40% to 60%. During flower, lowering your relative humidity level can help prevent mold and mildew from forming. To accommodate the lower RH, cooler temperatures will also help you maintain your ideal VPD.
Is 30% humidity too low for a grow tent? ›
Grow room humidity can't be that bad, can it? A little more or a little less humidity in your grow room won't hurt much as long as it's within 40-70%.
What is the best temperature for indoor grow? ›
For most grows, the ideal temperature range is between 65-80°F (18-26°C). Keeping temperatures within this range helps maximize plant growth and development and contributes to large and healthy buds.
What is the optimum temperature for plants to grow? ›
Thus, plants should generally be grown at warm temperatures of 70°F to 75°F to avoid excessively long production times. By growing cold-sensitive crops at warm temperatures, you can actually reduce the amount of energy used for heating — on a per-crop basis — than if they were grown at cooler temperatures.
Will mold grow at 55 humidity? ›
That's why experts recommend you keep humidity levels in your home at 55% or lower. Mold needs 55% or higher humidity in order to grow. Also, remember that reducing humidity below 30% isn't a good idea, either. This can cause health problems, making your eyes nose and skin dry, and exasperate lung and skin conditions.
Do plants grow faster in high humidity? ›
Data from published works concluded that the plant growth improved with increasing humidity, as higher humidity conditions help to keep the stomata open to maintain the photosynthesis process and minimize evaporation process of the plants.
What temperature should my grow room be when the lights are off? ›
Temperatures with lights on: 64-75 F° (lights off: minus 9-18 F°)
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What is the best bud hardener? ›
Available as Liquid KoolBloom or Dry KoolBloom, this additive is widely regarded as the best bud hardener out there.
What is the best flowering nutrient? ›
To stimulate blooming, choose fertilizers with a higher percentage of phosphorus compared to the percentage of nitrogen and potassium. Healthy flowers start with vigorous root systems, and a potassium boost can ensure your flowers get a good start.
Do fans help with humidity in grow tent? ›
You can also quickly bring humidity down with a small clip-on fan. These are pretty much a grow tent essential, as stale, stagnant air creates a breeding ground for molds and mildew.
What happens if humidity is too high in flowering? ›
This is because the flowers need to be able to absorb water through their petals, and if the humidity is too high, the flowers will be too wet and won't be able to absorb the water. If the humidity is too low, the flowers will dry out, and they won't be able to absorb the water.
Is 70% humidity too high for plants? ›
Humidity is a measurement of water vapor in the air (and is usually the culprit of bad hair days), but it's very important to plants, especially houseplants. Houseplants appreciate a humidity level between 60 and 80%, which would be difficult to maintain for an entire house—even more in the winter when the heat is on.
Do plants need cool or warm humidity? ›
Plants can benefit from both warm and cool-mist humidifiers, but the choice between the two depends on the needs of the specific plants and the environment they are in.
How much humidity is good for plants? ›
An ideal humidity level for most adult plants is 60% to 70%. Some tropical plants are used to humidity levels of up to 90%. Many succulents, such as cacti, only need 10% humidity. As a general rule, plants with thicker leaves can tolerate lower humidity levels.
What is the ideal moisture level for plants? ›
What is Soil Moisture and Why Does it Matter? Soil moisture is a measure of soil health, the water content present in a certain area of the ground. All plants need to be in a specific soil moisture range — the majority of plants thrive in soil with a moisture level that ranges between 20% and 60%.
