So this will be quite a fun bit! And we [yes I know it's just me lol] get started on this quite quickly! What kind of sensors will we need? Will we want to record all the sensor data to a mySQL database? We'll want to to output sensor data to a screen locally, And also output to a a smart phone too. And a not-smart phone via SMS. I imagine we can do something with Microsoft Azure IOT platform too.

Anyway, so the zones we have which require sensors are:

• Lighting zone, i.e. LED lighting
• Plant zone, i.e. the leaves and stems. Would also include the baskets the plants are housed in
• Root zone, i.e. yup the roots which are exposed in this zone
• Water-supply zone/reservoir

Well, for the plant zone we need to monitor gases, and temperature. We could also take images of the plant leaves. We don't need to monitor light since we know what the LEDs will output. Perhaps we should monitor relative humidity here?

For the root zone, we need to again monitor gases. Although since the plant-zone and root-zone are not hermetically sealed the gases are going to be the same. We mostly need to monitor relative humidity. And temperature too. 

For the water-supply zone, we need to monitor the water-level in the reservoir, pH in the reservoir, and TDS (total dissolved solids) in the reservoir too.

Anyway, so we can get this all prototyped fairly easily! 

Now the hardware for this, I think, is going to be a GrovePi+ HAT for the Raspberry Pi, and using the Grove sensors. They have a really extensive range of gas sensors [see https://wiki.seeedstudio.com/Sensor_gas/]