Agricultural & Greenhouse Monitoring

You don't need WiFi or any internet connection — Blue Maestro loggers record to onboard memory and transfer readings over Bluetooth to the free bmLogger app whenever you walk within range, typically around 30m indoors and up to 100m in open space for the Disc Maxi. The Disc Maxi 3-in-1 stores 50,000 readings, so it keeps logging between visits to remote polytunnels and field sites. If one location does have internet, a BM Gateway can push that site's data to bmCloud for remote access.

For most growers it's the Disc Maxi 3-in-1 with Alerts ($43.50), which measures temperature, humidity, and dew point with a ±0.1°C Sensirion SHT4x sensor, stores 50,000 readings, and runs up to 5 years on one battery. Those three parameters cover both growing zones and post-harvest storage, and configurable alerts flag frost or heat events as they happen. For humid propagation areas, washdown zones, or outdoor polytunnels, the waterproof Disc Mini IP67 ($52.00) is the better fit.

Condensation forms whenever leaf or surface temperatures fall to the dew point, and wet foliage is a primary trigger for fungal disease. Tracking dew point directly shows how close your greenhouse is to condensation risk at any moment, which a humidity percentage alone doesn't tell you. Both the Disc Mini 3-in-1 ($33.50) and the Disc Maxi 3-in-1 with Alerts log temperature, humidity, and dew point together, and the Maxi can alert you when a threshold is crossed.

The Disc Maxi runs up to 5 years on a replaceable CR2477 coin cell, so a sensor in a polytunnel or grain store can log across multiple growing seasons without a maintenance visit. The smaller Disc Mini uses a CR2032 lasting about a year, and the Disc Mini IP67 has a sealed battery to preserve its waterproof rating. For remote agricultural sites, the Maxi's 5-year battery life is usually the deciding factor.

Blue Maestro loggers keep timestamped records you can export as CSV or PDF from the free bmLogger app, and where traceable accuracy is required, a UKAS/NIST-traceable calibration certificate is available for $65. Farm-assurance schemes set their own documentation requirements and grant certification based on your complete farm management system, so check your scheme's standard or ask your certification body what environmental-monitoring evidence they accept — exported logger records and calibration certificates are the kind of supporting documentation you can provide.

You can start free: bmCloud's free tier covers up to 5 sensors and 1 gateway, enough for a single cold store or small greenhouse. Beyond that, the Small Business plan is $1 per sensor per month up to 1,000 sensors, with unlimited gateways and team members, SMS and phone alerts, and scheduled reports for audit records. The BM Gateway itself is $89, connects up to 40 sensors over WiFi, and both the gateway and bmCloud are covered by a 30-day money-back guarantee.