Vegetable is Alive is quite unlike any other game I've played, it's unique game-play and aesthetic makes for a pretty relaxing experience. I think you have made an excellent foundation to build up off. I am sure you've got some ideas for development but here are some suggestions: Look into and incorporate something like the Mycorrhiza Network (A fungal Network that connects trees to communicate and share resources as well as allowing dying plants to offload nutrients to other plants) Honestly it's really interesting and impressive stuff that could definitely flesh out the game play. This network can also be exploited with some plants like orchids hacking into the network to steal resources and other species like the black walnut can send toxic chemicals to sabotage the competition.
Things like this would really push your concept further. Also considering affects from weather or insects, I look forward to see your developments and thank you for such a unique game play experience!