The other day I came across the Raspberry Pi NoIR camera module (see https://www.raspberrypi.org/products/pi-noir-camera/). If you haven’t heard about it (that would surprise me!), the Raspberry Pi is a credit-card sized computer that comes with a fully functioning operating system (although there are different operating systems that can be installed on it, depending on your use-case). It is also extensible and comes with different modules (such as the NoIR camera) which can be programmed to do what you want/need.
The NoIR camera has the ability to collect infrared images so can be used for monitoring plant health. This is down to the fact that plants generally reflect near-infrared wavelengths more than they do light in the visible part of the spectrum. If a plant is stressed, the amount of reflected infrared light will be lower than usual. Although some calibration of the sensor would be required, there are other location and environmental monitoring modules that can be used with the Raspberry Pi so a relatively cheap and very customisable sensor pack could be yours to monitor your greenhouse, garden, shower mould etc.
I think it’s time that we at Geoger got hardware hacking!