great game! here's my tips for an update from my experience:
1. Nerf rocket plants:
Rocket plants are too op they should have less HP and damage
2. The insta-grow glitch should get patched:
Using insta-grow on an already grown plant will cause the rocket plant to fully recharge
3. Flying enemies and missile bells:
The flying enemies are extremely weak same applies to missile bells being boring and only one-use
4. New plants:
I've though of a effect within a 5 tile radius where all coins are automatically collected or at least 50% of the original value
(Same with a instant damaging effect)
5. Another rocket plant "glitch"
If a rocket plant kills an enemy off the screen we are not able to collect the coins from the enemies, two solutions:
The coins get automatically collected off the screen
Enemies spawn in a already-see area
6. More stats would be cool
"Money for beating 22th lvl" HP displayed on enemies,
7. Game lore expanding; more to explore like more items ground enemies and so
Somehow a technique to unlock more area for plants...
i could go on forever