--- title: "Greenhouse IoT Sensors over MQTT: Climate & Substrate | ConnectMQ" description: "Stream greenhouse temperature, humidity, CO₂, PAR light and substrate moisture and EC to your climate computer and grower app over MQTT, with alerts per zone." url: "https://connectmq.com/use-cases/greenhouse-iot-sensors/" language: "en" --- Use case # Every greenhouse zone, measured live Wireless sensors and gateways in each compartment publish temperature, humidity, CO₂, PAR light and substrate moisture and EC over MQTT. The integration with your climate computer, the grower app and your dashboards subscribe — and threshold rules alert the grower when a zone drifts out of range. [Try it free](https://app.connectmq.com/signup) [See pricing](https://connectmq.com/pricing/) No card required Used in - [Agriculture](https://connectmq.com/industries/agriculture/) Example message PUBLISH greenhouse/site-1/house-3/zone-2/climate ``` {"t":23.4,"rh":81,"vpd":0.55,"co2":780,"par":412,"ts":1761120000} ``` QoS 1 · TLS 8883 · PUBACK The problem ## One measuring box for a whole compartment The climate computer usually steers on one or two measuring boxes per compartment, while the crop sees cold corners, wet spots and slabs that dry out faster than the rest. Growers add wireless sensors to see that variation, but every vendor brings its own gateway and app, and the data rarely reaches the climate computer, the grower’s phone and the cultivation records together. ## How it works 1. 1 ### Sensors measure the crop climate Wireless sensors in the canopy and in the substrate measure temperature, humidity, CO₂, PAR light, substrate moisture and EC in every zone. 2. 2 ### Gateways publish over MQTT A gateway per house publishes the readings to ConnectMQ over TLS — on change or every minute — and a Last Will marks the gateway offline if it drops. 3. 3 ### Climate computer and apps subscribe An integration service feeds the readings to your climate computer or control strategy, while the grower app, dashboards and cultivation records subscribe to the same topics. 4. 4 ### Alerts reach the grower Threshold rules watch for high humidity at night, CO₂ far below target or a slab drying out, and notify the grower so they can act early. ConnectMQ ## What it needs from the broker ### One topic tree per site Site, house, zone and sensor in one hierarchy: the grower subscribes to a whole house with a wildcard, an advisor to a single zone. ### Retained last values A dashboard or app opened in the middle of the night shows every zone’s current climate at once, without waiting for the next reading. ### Threshold rules and alerts Rules on temperature, humidity, CO₂, EC or moisture send a notification when a zone leaves its range, and the live dashboard shows which one. ### Separate credentials per party Sensor gateways, the climate computer integration and crop advisors each get their own credentials and topic ACLs, so everyone sees only what they should. ## What you get - The microclimate visible zone by zone - Sensor data from several vendors in one place - Alerts on the grower’s phone, not only in the office - Readings ready for cultivation records and analysis Example topics ``` greenhouse/site-1/house-3/zone-2/climate (retained) greenhouse/site-1/house-3/zone-2/substrate (retained) greenhouse/site-1/house-3/gateway/status (retained) greenhouse/site-1/house-3/alerts ``` ## Industries that run this use case [![](https://connectmq.com/images/industries/hero/agriculture.webp) Agriculture](https://connectmq.com/industries/agriculture/) ## Related solutions [ ### Smart Agriculture Soil probes, weather stations and irrigation Learn more](https://connectmq.com/smart-agriculture/) ## Frequently asked questions How do I connect greenhouse sensors to MQTT? Most wireless greenhouse sensors report to a LoRaWAN, Zigbee or vendor gateway. Configure that gateway — or a small Node-RED flow on an edge PC — to publish each reading to your ConnectMQ broker over MQTT/TLS, on topics such as greenhouse/site-1/house-3/zone-2/climate. Can MQTT sensor data feed my climate computer? Usually through an interface the climate computer vendor provides, such as an API, OPC UA, Modbus or a data import. A small integration service subscribes to the MQTT topics and writes the values through that interface. Check which external inputs your system accepts; the control logic stays in the climate computer. What should a greenhouse monitoring system alert on? Typical alerts are temperature outside the setpoint band, high humidity or low VPD (a disease risk), CO₂ far from target during dosing, low substrate moisture or EC drifting from the recipe, and gateways going offline. On ConnectMQ you set these as threshold rules on the sensor topics, and Last Will covers the gateways. ## Build it on ConnectMQ Start on the Free plan — no card required — connect your first devices today and upgrade when you go live. 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