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Indoor Farming | Temperature and Humidity Sensors in Agriculture

Temperature and humidity sensors in agriculture

For a vegetable grower at any skill level, there's nothing better than walking to your garden and seeing what's shaping up to be a bountiful harvest.

That's weeks of hard work and careful attention about to pay off.

Though indoor agriculture is markedly different from traditional agriculture, hard work and constant attention still apply – especially when it comes to keeping conditions exactly where they need to be. 

While all elements of an indoor climate matter for optimizing the growth of vegetables, there are two that can be considered more important as their negative effects can be drastic: temperature and humidity. In short, both …

Whether you're designing a climate control system for a  smart greenhouse or a large vertical farming operation, having temperature and humidity sensors for agriculture indoors is an absolute must.

In this article, we'll dig into:

  • Agricultural temperature sensors
  • Agricultural humidity sensors
  • Placements for both sensor types
  • Sourcing the best indoor agriculture sensors
  • & much more

5 Must Spots for Indoor Agricultural Temperature Sensors

Temperature sensors in indoor vegetable growing operations are used in several key areas to ensure optimal growing conditions:

  1. Near plant canopies: To monitor the microclimate affecting the plants directly.

  2. In the growing medium: To assess the root zone temperature, which influences nutrient uptake and root development.

  3. Air inlet and outlet points: To regulate and adjust the indoor air temperature.

  4. Near lighting systems: To prevent heat stress from artificial lighting sources.

  5. In water reservoirs: To control the temperature of water used for irrigation, affecting plant hydration and nutrient absorption

Agricultural Temperature Sensors for Indoors

Let's get right to it.

In  controlled environment agriculture for vegetables, temperature has a big impact on the growth and development of healthy, fruit-bearing plants.

By maintaining precise control over temperature – whether it's the ambient conditions or directly in the growing media – you can:

  • Optimize plant health
  • Enhance growth rates
  • Improve yields

In a certain respect, that's no different than what happens in the natural environment. Suppose temperatures go to extremes on either side of the thermometer or put undue stress on a plant for an extended period of time. In either case, that's a fast recipe for crop underperformance or outright failure.

What's more, without proper temperature cycling that mimics nature (or additional controls), unchecked temperatures can create optimal environments for plant diseases and molds.

While there are many different types of temperature sensors used in indoor farming, those designing controlled environment systems often choose between two types: NTC thermistors and RTD temperature sensors.

Let's look at both types.



What is an NTC Thermistor?

An  NTC (negative temperature coefficient) Thermistor is a type of resistor whose resistance decreases as the temperature increases. NTC thermistors are made from semiconductor materials that change their resistance with temperature changes. Due to their high sensitivity to temperature changes, they are widely used in measuring and controlling temperature in applications where precision and immediate reactivity matter most.

With their ability to accurately monitor slight changes in temperature, NTC thermistors are invaluable for maintaining the exact conditions needed for optimal plant growth in indoor agriculture.

What is an RTD Temperature Sensor?

RTD (resistance temperature detector) Temperature Sensors operate using the principle that the resistance of a metal increases with temperature. RTD sensors leverage the predictable change in electrical resistance of certain metals, such as platinum, as they are exposed to varying temperatures. This characteristic allows for precise and stable temperature readings over a wide range, making them well-suited for helping to maintain the conditions required in indoor agriculture.

NTC Thermistors vs. RTD Temperature Sensors in Indoor Agriculture

While both types of temperature-measuring sensors provide the same type of data used for triggering climate control systems, NTC thermistors remain the more popular choice.


Several reasons: 

  • Cost-Effectiveness: NTC thermistors are generally less expensive than RTDs, making them a more cost-effective option for indoor farming operations of all sizes.

  • Ease of Deployment: NTC thermistors are easier to deploy than RTDs. Their small size and flexibility in terms of packaging options allow for easy installation in various parts of an indoor farming setup, including direct placement in soil or integration into irrigation systems.

  • Resistance-Based Measurement: NTC thermistors utilize resistance to measure temperature changes, which is particularly advantageous in the dynamic environment of indoor agriculture. Their high sensitivity allows for the detection of small temperature changes, enabling more precise control over the growing environment. This level of control is crucial for optimizing plant growth and health.

  • Packaging and Versatility: Whether it's monitoring air temperature or being embedded directly into the soil to measure root-zone temperature, with the right packaging NTC thermistors can be adapted to a wide range of applications – say, put directly in soil.

Humidity Sensors for Agriculture Indoors

Like temperature, humidity can make or break the success of indoor vegetable growth.

When kept inside an optimal range, humidity  levels can:

  • Prevent plant dehydration
  • Encourage root growth
  • Limit fungal diseases

On the flip side, high humidity levels (above 80%) create the ideal environment for mold and other pathogens to thrive. By contrast, if humidity levels are too low (below 30%), plants will experience stress as they struggle to absorb water through their roots.

5 Must Spots for Indoor Humidity Sensors for Agriculture

Humidity sensors in indoor vegetable growing operations should be placed in several key areas to ensure optimal growing conditions:

  • Above the plant canopy: To monitor the humidity level that directly affects transpiration and photosynthesis.

  • Near ventilation systems: To assess and control the humidity of incoming and outgoing air.

  • Inside the growing medium: To measure soil moisture levels, which influence water uptake and root health.

  • In propagation areas: To ensure high humidity levels needed for seed germination and cutting propagation.

  • Storage and processing areas: To maintain humidity levels that preserve the freshness and quality of harvested vegetables. 

Types of Humidity Sensors for Agriculture

There are several types of humidity sensors used in indoor agriculture. The two main types that indoor agriculture system designers typically choose between are:

  • Capacitive Sensors – These sensors detect humidity levels by monitoring changes in electrical capacitance, which occur by the absorption of moisture.

  • Resistive Sensors – Humidity measurement through these sensors is based on alterations in the electrical resistance of hygroscopic materials in response to moisture.

It's worth noting there's a third, less-used option:

Thermal Conductivity Humidity Sensors – These sensors determine humidity by measuring the thermal conductivity of the air, which changes with moisture content. The principle relies on the fact that the thermal conductivity of air varies with the amount of water vapor present. These sensors are less commonly used for humidity measurement in typical indoor agriculture or HVAC applications due to their operational complexity and the specific nature of their sensitivity to humidity changes.

While they offer a unique approach to measuring humidity, thermal conductivity sensors are more specialized and may not provide the same level of convenience or cost-effectiveness as capacitive or resistive humidity sensors.



Capacitive Vs. Resistive Humidity Sensors for Indoor Agriculture

In most cases, capacitive sensors are the go-to choice, as they offer: 

  • Enhance Accuracy and Stability: Because of their functionality, capacitive sensors offer more precise humidity readings that are repeatable.

  • Longer Lifespan: Compared to resistive sensors, capacitive types are designed for extended use without significant performance degradation.

  • Less Prone to Drift Over Time: Capacitive sensors maintain their accuracy over longer periods, reducing the need for frequent recalibration.

  • Reduced Susceptibility to Contamination: Capacitive sensors are less affected by dust, chemicals, and other contaminants, ensuring consistent measurement accuracy.

  • Cost-Effectiveness Over the Long Term: Despite a potentially higher initial cost, their durability and minimal maintenance requirements make capacitive sensors more economical for indoor farming.

In contrast, while resistive sensors are simpler and may be lower in cost initially, their lower accuracy, greater susceptibility to contamination, and tendency to drift over time make them less suitable for the precise and consistent humidity control required in indoor agriculture.


Capacitive Humidity Sensors

Resistive Humidity Sensors


High, typically within ±2% to ±5% RH

Lower compared to capacitive sensors

Reliability & Stability

Highly reliable with excellent long-term stability

Less stable over time, prone to drift

Sensitivity to Humidity Changes

Very sensitive, allowing for precise humidity control

Less sensitive, which may affect precise monitoring

Susceptibility to Contamination

Less susceptible, making them more reliable in varied conditions

More susceptible, potentially affecting accuracy


Longer, with minimal need for recalibration

Shorter, may require more frequent recalibration


More cost-effective over the long term due to durability

Initially lower cost, but less durable over time

Suitability for Indoor Agriculture

Highly suitable due to precision and reliability

Less suitable for applications requiring precise humidity control

Sensors for Precision Agriculture: Livestock

While indoor livestock operations are far different than those for growing produce, the need for robust and reactive agricultural sensors to monitor temperature and humidity remains the same.

Just as plants thrive in optimal indoor conditions within certain temperature and humidity ranges, so too do livestock. In a certain sense, the sensors used in a greenhouse also have a place in an indoor poultry farm.

With temperature and moisture sensors for indoor agriculture carefully integrated into climate control systems, you're able to better manage livestock:

  • Health and Comfort: Overheating or excessive moisture can lead to stress, illness, or even death, whereas an environment that's too cold or too dry can also have detrimental effects on animals.

  • Disease Prevention: High humidity levels can promote the growth of pathogens and parasites, which are harmful to livestock. By keeping moisture levels in check, the risk of diseases can be significantly reduced, leading to a healthier livestock population.

  • Productivity and Growth: The right environmental conditions can influence the feed conversion ratio, growth rates, and overall productivity of livestock. Animals in a stress-free environment with ideal temperature and humidity levels tend to grow faster and produce more, whether it's meat, milk, or eggs.

  • Ventilation Control: Just like in indoor vegetable farming, sensors can help manage ventilation systems efficiently in livestock buildings. By monitoring the indoor air quality and adjusting ventilation accordingly, farmers can ensure their animals are getting fresh air, while also conserving energy.

  • Waste Management:  By monitoring moisture levels, farmers can better control the drying and handling of waste, reducing odors and the potential for disease.

Selecting the Best Sensor Temperature and Humidity Sensors for Indoor Agriculture

For as delicate as controlled environments in indoor agriculture are, they are intense. 

Replicating the natural environment is no simple task and man-made indoor environmental conditions are always in motion and require constant monitoring. What's more, the data collected about a metric – say, soil moisture – needs to be accurate and reliable.

Suffice it to say, indoor agriculture sensor technology needs to be environmentally hardy – ready for not only the elements of a controlled environment but also to perform consistently over time.

When selecting temperature and humidity sensors for agriculture indoors, consider these factors:

  • Accuracy: Both temperature and humidity readings must be precise to maintain optimal growing conditions. Look for sensors with high accuracy ratings.

  • Response Time: The best sensors respond quickly to changes in temperature or humidity, which is crucial in the dynamic indoor farming environment.

  • Durability and Reliability: Indoor agriculture sensors need to withstand a range of environmental conditions for the long haul, including exposure to moisture, heat, and chemicals. Look for sensors with durable materials and proven reliability.

  • Cost-effectiveness: For indoor agriculture operations of all sizes, cost plays a role in sensor selection. Seek out high-quality sensors that provide the necessary accuracy and responsiveness at a competitive price.

  • Packaging and Integration Options: As we mentioned earlier, there are several types of temperature and humidity sensors available. Consider which options would best meet

  • Connectivity: An essential for modern indoor farming, look for IoT agriculture sensors. These sensors used in smart agriculture integrate with control systems’ remote monitoring and control, ensuring timely adjustments and data-driven decisions.

The best place to source the agriculture sensor technology you'll depend upon for your indoor farming?

Working directly with an advanced sensor manufacturer. With their technical expertise and experience, you can rest easy you're getting the best sensor technology for your operation and its climate control systems. As a bonus, your sensor manufacturer can create customized solutions to meet your exact requirements and applications, whether it's a greenhouse temperature sensor, a greenhouse humidity sensor, or even an entire greenhouse sensor system.

Temperature and Humidity Sensors in Agriculture | Improving Indoor Farming

Farming is changing, and it's largely becoming driven more by technology. The need for robust and accurate temperature and humidity sensors in agriculture indoors can't be overstated.

With the right agricultural temperature and moisture sensors in place, indoor farming operations can achieve greater precision, consistency, and efficiency in their climate control systems, leading to healthier plants or livestock and better returns on investment.

Upgrade Your Temperature and Humidity Sensors for Agriculture Indoors

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