Hi,
this sounds like a really interesting project - the plants are really beautiful and they deserve a good-looking, clean, modern website.
I think Wordpress would be a good choice for your store, it would allow you to easily add new products and change the existing, along with keeping the website multilingual without a hassle. I could completely redesign your website and create a custom responsive Wordpress theme and transfer all of your existing data. We could start with a simple mock-up and then improve it further until you're completely happy with how it looks before starting with coding. I would also create a written guide with screenshots, explaining how to manage the website from the admin area.
You can check out my Freelancer portfolio to see some of my work and if you're interested in a quick mock-up to show you how your new website could look just let me know.
I'd love to hear if there are any websites you like that could serve as an inspiration? Let me know if you're interested or if you have any questions, I'm looking forward to hearing from you.
Best,
Djordje