Neat idea to go with the theme! I liked the pixel art and the overall presentation. For me, something felt a little off about the game balancing, especially in the first level. Maybe it would have helped if the aphids moved a tad slower at first? Or allow the player to move faster? However, as I got better with the controls, I managed to find better ways to defeat them, so maybe the difficulty curve is alright. I know this is probably beyond the scope of what you could have done for the jam, but if you were to continue past two levels, I can see some potential for progression like facing more and stronger enemies while also allowing the player to have a faster rate of fire. There were some funny (perhaps unintentional?) moments, like when the aphids got stuck behind trees it looked like they were trying hide and sneak around. Also, if you die when the plant still has a lot of health, you can only lay there helplessly as the aphids wreck the poor little plant until the game over screen comes. Anyway, nice work!