Temperature plays a vital role in nearly all processes in cannabis production, including seed germination, drying, curing, and product quality. Growing conditions influence the growth, development, yield, quality, plant health, flower development, and the incidence of diseases or insects. Plant structure, branching, and stem and branch internodes are all affected by temperature.
When cannabis grow facilities, or personal use growers fail to grasp how temperature influences other environmental conditions, they produce substandard crops.
In this article, you'll learn why cannabis is affected by temperature and what you can do to properly control temps in your grow room for the best possible product.
Why Temperature Matters When Growing Cannabis
Temperature is one of the key environmental factors for cannabis cultivation. Certain strains are more sensitive to temperature, affecting the plants' yield and potency.
Ideal conditions for the cultivation of cannabis plants vary depending on the stage of plant life. The requirements for successful cloning are higher for both temperature and moisture than for vegetative growth and flowering plants. To master the art of cannabis growing, you have to understand the environment your plant will be in and be able to dial it in to cater to the specific needs of that plant. How should Growers adjust the humidity level and temperature of a grow room then?
Temperature and Humidity Measurement and Change
You will need a thermometer and hygrometer to measure temperature and humidity accurately. As well as a heater to raise the temperature and an air conditioner to decrease it. These can be placed outside or within the growing space depending on room size and fluctuation levels.
To increase and decrease humidity levels, growers can use humidifiers and dehumidifiers. It may be beneficial to use a controller that can monitor temperature and humidity and turn on the right appliances to maintain the proper levels in large grow rooms.
It's important to note even without CO2 enrichment, cannabis plants of all stages can grow at slightly higher temperatures under bright lights (such as LEDs or HPS 600W and brighter) as long as there is low relative humidity and plenty of air movement.
Best Temperatures for Cloning
Warm conditions with high humidity are ideal for cannabis cuttings to root. Since clones lack roots yet, all their water comes from the transpiration of leaves until root systems are formed. As a result, clones prefer humid conditions, characterized by abundant evaporation of water in the air. Therefore, humidity domes or cloners are used to raise the humidity artificially for clones. Plastic trays and domes, like the Floraflex Incubator Kit, are perfect for this. During cool weather, Growers should place a heated mat with a piece of carboard on top of it beneath the trays to maintain an appropriate temperature of 76-79°F in addition to 64-68% relative humidity inside the dome.
It would be best if you prioritized warmth and high humidity wherever and in whatever medium you plan to root your clones. Crops exposed to cold or dry conditions are likely to perish quite rapidly. But remember, too much humidity (above 90%) can also cause mold and rot. Floraflex Incubator Domes allow growers to control airflow for the perfect conditions.
Best grow room temperature for the vegetative stage
During the vegetative growth stage, the ideal temperature is 82-86 degrees Fahrenheit during "daylight hours" and no less than 77 degrees during the "night," with a relative humidity of 72-78%. By setting your system to these settings, your plants will have the best chance of capturing light as energy in order to grow. Plants grow leaves and branches at this time and expand their root systems throughout the growing medium. Overheating or being too cold will prevent growth, and the plants might even die.
Best grow room temperature for the flowering stage
At night, it should not be more than 5-10 degrees cooler than 82-86 degrees during the flowering stage. You can have daytime temps of 72-81 if you supplement with CO2.
Growers should reduce the relative humidity to 65-70% during early flower, 55-65% in mid flower and 45-50% for the last two weeks before harvest. Doing so will avoid issues like bud rot, mold, and powdery mildew, which are often a result of higher humidity.
Best Temps For Harvesting Cannabis
It is important to monitor the drying room carefully. As your plants dry, they will release a great deal of moisture into the room. Air must circulate in the room to rid the room of wet air without having the fans blow directly on the branches, which would cause them to dry out prematurely, resulting in buds with a nasty taste and harsh burn.
Ideally, a drying room should have a temperature between 55 and 65 degrees Fahrenheit and 55 - 65 percent humidity in a well-ventilated dark room. Cannabis compounds such as cannabinoids, terpenes, and flavonoids are susceptible to evaporation and release at temperatures above 80 degrees, which will decrease the flavor, potency, and scent of your buds.
The buds will feel popcorn dry on the outside after 6 - 10 days and your branches will snap instead of bending. This is the time to start cutting off the bud and putting it in jars. You should cure your buds in a dark and cool place (68-72 degrees Fahrenheit).
The temperature in a grow room affects what else?
- Color of Buds - Your plants' buds and leaves are affected by the temperature they experience. If your strain has the genetics to produce blues, purples, or pinks, the temperature either suppresses or brings them out.
- Growing Patterns of Plants - Your plant's growth can actually be affected by temperature fluctuations. In general, warmer nighttime temperatures slow growth upward. During the night, cannabis tends to grow best if it's cooler. Keeping your plants at a lower temperature during the dark period will encourage their growth.
- Humidity - Your growing area's relative humidity is greatly influenced by the temperature.
For Your Grow Area, Choose Proper Grow Lights
There is concern among many cannabis growers regarding the temperature of their grows room as a result of their indoor grow lights. This section will go over everything you need to know about heat production from grow lights.
Growing under High-Pressure Sodium (HPS), Metal Halide (MH) and LECs
It is well known that MH/HPS/LEC grow lights use a great deal of electricity and produce a great deal of heat.
250 Watts of HPS light will produce close to the same amount of heat as 250 Watts of CFL lights, but you will get more light and more efficient results using HID lights. Another advantage of HIDs over smaller lights such as CFLs is that they come with pre-engineered exhaust systems to allow for proper cooling.
LEDs
A coveted toll for growing cannabis, LEDs are known for needing just a little electricity to produce a lot of light. And unlike HID grow lights, they produce little heat. Another advantage of LEDs is they use very little power to run, which means you can use fewer of them. LEDs also last longer than HID grow lights.
LED grow lights are increasingly becoming popular with commercial cannabis growers. The lights use specific wavelengths that have been shown to increase THC production.
Depending on the wavelength of light they are exposed to, cannabis plants respond differently. Cannabis plants in the vegetative stage respond best to blue light between 400 and 500 nm. Plants are encouraged to grow large, healthy, and strong leaves at 460 nm. For the highest yields, red light from 620 to 780 nm can be used in the flowering period. Photosynthesis and plant growth can be impacted by choosing a growing light spectrum of ideal wavelength 660 nm.
Conclusion
Temperature affects cannabis plants in many ways. Adverse conditions, such as cold, heat, drought, and high humidity, can negatively affect the quality and quantity of resin produced.
The growing of cannabis is a very complex process, and there are many variables that can affect yields. Among these variables are the growing conditions, which include the temperature and humidity of the grow room, as well as photoperiod, ventilation, lighting, use of nutrients, and pest control. For optimal results, growers must carefully monitor all of these variables throughout the cloning, flowering, and harvest stages.
