EasyBloom is a sensor that you can stuck into the earth close to a plant or where you would like to grow something. Various sensors then measure various parameters (temperature, light, humidity) that can be downloaded via USB after 24h. Recorded sensor data is then compared with the requirements of 5000+ plants on the EasyBloom website, which then tells you whether this spot is suitable for a particular plant and can recommend alternatives.

http://www.easybloom.com/learn/overview.html