Leaf and Bud Temperature Sensor

Provides on-site, real-time warning of radiation frost events

Beeservices  leaf and bud temperature sensor (formerly called the radiation frost detector) is an innovative temperature sensor designed to mimic leaves and flower/fruit buds, which can sometimes drop well below the ambient air temperature due to long-wave radiation loss on clear, calm nights. Knowing exactly when a radiation frost event is occurring allows you to activate frost protection equipment in time to protect your crops and eliminates starting frost protection too early, which wastes money.

Monitor Radiation Frost Events

On calm, clear nights surface temperature, including leaf and bud temperatures, can drop well below air temperature due to a net loss of longwave radiation to the clear sky. A radiation frost occurs when frost forms at the surface before the air temperature reaches freezing (0 C). Under cloudy and/or windy conditions, radiation frost events do not occur. The Apogee radiation frost detector is a combination of two high accuracy thermistors mounted in a single housing. One sensor is designed to mimic a leaf and sensor is designed to mimic a bud, providing estimates of leaf and bud temperatures and a direct means of monitoring radiation frost events.

Figure1: Leaf and bud temperature approximations measured with an Apogee SF-110 compared to air temperature (top panel) and wind speed (bottom panel) on the evening of April 28, 2012. Leaf and bud temperatures were both below air temperature after 8 P.M. and reached freezing 6 (leaf) and 4 (bud) hours before the air temperature.

Wide Range, Accurate Measurements

Thermistor accuracy is ± 0.1 C across a range of 0 to 70 C, providing accurate measurements at temperatures near zero where frost damage is likely to occur.

Typical Applications

Applications include leaf and bud temperature estimates in cropped fields, orchards, and vineyards. Leaf and bud temperatures returned by the detector can then be used to alert growers to the potential of frost damage to crops.

Output Options

Analog and digital output options are available. Analog version is an un-amplified voltage output. Digital version is SDI-12 communication protocol.


The AM-220 mounting bracket is designed to orient sensors at varying angles to satisfy all applications. The bracket can be mounted to a mast or pipe, while the sensor bracket will accommodate the sensor.

Warranty and Support

All Apogee products are backed by an industry-leading four year warranty and outstanding customer support.