I'll admit I got a bit of a fright when the plants started coming after me, and I thought it was really interesting. It's a very cool mechanic, growing your own enemies and building your own waves that way.
I'd love to see you take the idea of different enemies further, each with their own characteristics, and also improve the overall feel of the combat. One thing that would help tremendously is some kind of hit indication, like the character flashing white. I also missed having a few sound effects to reinforce the combat side of things.
Overall, I think the game has potential! You should definitely keep working on it!