I’ve set up a “headless” Raspberry Pi Zero to monitor my little garden, using a humidity/temperature sensor and a camera, it runs a minimal webserver (lighttpd) so I can view stats/images anywhere in the house from a web-browser.
Assuming you have the tools, the whole thing should cost less than 20 Euro.
You don’t need to know anything about Linux or Raspberry Pi to build this, but you will need to do some soldering, thou there might be a way to avoid this by using dupont-wires.
I’m not be an expert in the field, but if you have any questions, feel free to ask them in this thread, I’d also like to hear from you if there are details missing, or if you have an idea to improve the project.
The project is GPL3 and hosted on gitlab: https://gitlab.com/wildflower/rpi-garden
To build upon my previous response, I’d advice using template matching of plant leaves for instance, just as in this example, “Template Matching with Multiple Objects”, on the bottom of the page with the Mario coins.
Could be a good starting point if you’re interested on building this further.