Stage 4-3

Uh-oh. A new Zombie. Your cactus should take care of it though.

Plants

 * Sun-shroom
 * Sea-shroom
 * Puff-shroom
 * Cactus
 * Plantern
 * Lily Pad
 * Anything else is OK.

Zombies

 * Zombie
 * Conehead Zombie
 * Ducky Tube Zombie
 * Balloon Zombie

First...
Plant Sun-shrooms, Puff-shrooms, and Sea-shrooms as normal, adding Lily Pads if necessary. Use the Planterns to kill the fog, and Cacti to deal with the Balloon Zombies. Implement your strategy for anything else you added.

Then...
Use Blovers instead of Cacti and Planterns. Anything elso won't change.

Result

 * Blover
 * Stage 4-4