Fun! I was impressed with the movement and animations given the development time frame.
You've got a compelling atmosphere and interesting visuals, and a decent gameplay loop.
Some notes on possible improvements:
Variety of play: there's no strategy to placing plants anywhere, I found the best way to play was to just hold all the buttons and put down as many as you can in one place.
Orientation: I didn't feel any motivation to keep me drawn in -- there's no story hook, and there isn't really a positive feedback loop for defeating enemies. You get more "power" but it feels secondary to the game and unimportant.
Feedback: All the little interactions in this game should have feedback -- there's sounds for being attacked and hitting enemies (plus the particles, those are great), but I found myself just mashing Q trying to pick up plants, not even knowing what I was picking up or from where (highlight pickup radius? highlight pickable plants?).
Given the 1 week we had to develop, y'all did great. Love that this game feels well put together in an atmospheric sense and that there's a relatively satisfying moment to be had once you've got a large group of enemies and a lot of plants. My critiques are just the sticking points I noticed were holding back your strong points. Keep working!