I am currently working on a Visual Recognition App (VizRec - check the webpage at www dot VizRecApp dot com).
There is a part of this app which will work perfectly for your plant recognition needs.
Relevant Skills and Experience
I have some very useful visual recognition development skills, and some software already developed that will take a photograph, then match it against a database of similar images.
Proposed Milestones
$150 USD - Project startup milestone. Covers Freelancer's commission taken at the start
$150 USD - Agreed project scope and design
$500 USD - First deliverable showing a working framework of the app, with main features already included
$500 USD - Main features completed, and tested to customer satisfaction
$200 USD - App delivered to customer, or uploaded successfully to the Apple AppStore
Additional Services Offered
$50 USD - I can provide all the necessary app graphics and icons
$100 USD - I can provide an online database, such that multiple users can access the same data.
My current visual recognition app takes a photo (in this case of a users face), then matches it against a database of similar images. It provides the closest match available, along with basic data (an ID) which allows the app to look up an online database of information.
In the case of your project, it would match the plant photo against a database of all your plants, then look up the necessary plant watering information.
My current app works successfully, and would suit your needs well. Of course it would need small modifications to be completely suitable.
Please feel free to contact me to discuss.
Thank you