I really liked this one. It took me a few minutes to figure out how to play, but after that I had very little issue with the gameplay (just the need to step off of farmland occasionally to make it realize I'm on the farmland and can plant more). Enjoyed running back and forth planting and selling stuff!
If you keep working on this project, I'd suggest maybe adding some way to see that you're moving when going through the center of the play area. Maybe a slight texture for the ground, or a few small objects. Just so you can tell you're moving. After I finished my first playthough, I immediately played it again to try for a better run.
I loved the art, and the base idea (as well as how you implemented it) is a great. Farming and wave-based combat? Good combination!
I really enjoyed this entry. Nice job! :D