Environment Sensors

Humidity and Temperature

There are many generic humidity and temperature sensors that are cheaply available. Some connect to a smartphone via Bluetooth and provide a graph of data while others incorporate a smaller LCD to display current readings

Light Sensors

"Quantum" sensors are able to measure the intensity of a light source accurately but are very expensive. Alternatively, ‎there is an ios only app called Korona - Plant Light Meter that can measure PPFD