Soil Temperature Probe 

 At soil temperatures less than 6 degrees Celcius, most ryegrass stops growing.

Although it doesn't transmit the temperatures, it will show the highest and lowest temperatures over a time period, so you can also use it to check the operation of coolstores and refrigerators.

It will also measure the temperature of cooked goods - once outside the oven.

Measures from -50 to +200 degrees Celcius, (Fahrenheit option) with an error of +/- 1 degree Celcius. It shows readings in 0.1 degree increments. It updates the screen every 0.7 seconds, and can respond to a change in temperature from 25 degC to 100 degC in 8 seconds. It comes supplied with an LR44 battery installed, and the battery life is 5,000 hours.