Temperature and Relative Humidity in Greenhouses and Cannabis Production

There’s a saying: “An ounce of prevention is worth a pound of cure,” and this is no different with your sensors and controls of the greenhouse/indoor farming equipment that you use and rely upon everyday. Similar to any controlled environment, it is vital to monitor and proactively interpret the pressure, temperature, relative humidity, carbon dioxide (CO2) supplementation, and irrigation of your growing space. Losing control of your environment can lead to cultivation headaches ranging from poor air flow to extreme temperatures; additionally, high humidity and low irrigation rates can lead to the spread of disease and viruses. 

Fall is a peak season for humidity-related diseases in greenhouses. Sunny days increase the transpiration of moisture from leaf surfaces and evaporation from soil. The warm air holds the moisture in the vapor form. At night as the air cools to dew point, condensation occurs and water droplets are formed on cooler surfaces. Do you know what your greenhouse indoor air quality looks like?

Carbon Dioxide Transmitter, Series CDWP

Proper control of temperature and relative humidity is ever changing from the early stages of development all the way through the cultivation and curation process. Accurate, reliable, and sustainable solutions equal efficient and healthy harvests. The Dwyer Series RHP relative humidity and temperature sensor, Series CDT carbon dioxide sensor, and Series CDWP carbon dioxide sensor are excellent solutions for monitoring and controlling your process.

From seedling to final product, temperature and humidity are key. Here are some optimal conditions that Dwyer sensor solutions can help with.


Seedlings and clones like high humidity levels of 65-70% 

Temperatures with lights on: 68-77 F° (lights off: 8-9 F° lower) 

The increased humidity levels allow seedlings to take water in through the leaves while their root systems are developing.


Humidity levels can be lowered by 5% each week (acceptable range: 40-70%)

Temperatures may be increased slightly if desired.

Temperatures with lights on: 71-82 F° (lights off: 8-9 F° lower)

As the roots are now more developed, they’re able to perform most of the needed water uptake with evaporation through the leaves now cooling the plants.


Humidity levels need to be lowered to 40-50%

IMPORTANT– Never above 60% humidity!

Temperatures with lights on: 68-79 F° (avoid high temperatures)


Whichever method you choose for trimming your product, suitable conditions for your drying room are important. You’ll want a cool, dark environment with temperatures in the range of 59-71°F and humidity at or near 50%. Even after the growing process is completed, it’s necessary to be concerned with temperature and humidity.


On top of the need for specific temperature and humidity controls throughout the growing process, the humidity level during the drying process is equally important to the quality of the final product.


Monitoring during the manufacturing and supercritical CO2 extraction process. Accurate level control helps achieve the best quality product and indoor air quality and safety of production staff.

Monitoring your growing operation’s conditions is essential. It is not possible to make the right decisions without having the right information. Temperature and relative humidity need to be monitored in every greenhouse. Light levels should be checked at least periodically to make sure covering materials are performing adequately. Ideally, light levels need to be checked on a regular basis in order to know the optimal temperature regime for the crop.

Temperature/Humidity Transmitters, Series RHP

Dwyer Instruments’ innovative sensors are used in commercial greenhouse operations around the world to directly monitor the plant’s conditions. Our products help give growers access to continuous measurement of a wide range of aspects of plant growth. The integration of this information into production decisions is rapidly providing better data about growing conditions and helping to prevent plant stress occurrences.

Planned and predictive control of the greenhouse is the ultimate aim of a controlled environment horticulture and greenhouse solution. The most important benefit is the efficiency and effectiveness of your management decisions to save money and result in a better crop. Other benefits include greater energy and labor efficiency, more efficient use of water and fertilizers and fewer pesticides.

If you have any questions about selecting products for your application, the Dwyer Applications Engineers are available to assist by phone at (219) 879-8868 x6402, or by email at tech@dwyeromega.com.

To learn about how Dwyer products are used in other agricultural applications, please visit our website: https://info.dwyer-inst.com/2023-agriculture