When the level begins, the belt will only give Peashooters and Chard Guards. A Cave Zombie will come in both the third and fifth rows, while a Conehead Cave Zombie comes in the fourth row.
Plant Peashooters in the first column to take out the Cave Zombies out, and place a Chard Guard in the fourth row to stall the Conehead Cave Zombie. Once another Peashooter is given, plant that to take care of the Conehead Cave Zombie.
Continue to build your defenses, placing a Chard Guard in each of the following spots:
Fourth column, third row
Fourth column, fourth row
Fourth column, fifth row
Build Peashooters behind the Chard Guards, making sure that the top two rows are defended to protect against Dodo Rider Zombies. Save the given Chard Guards to heal the already planted ones when they are low on leaves.
About halfway through the level, the Peashooters will stop coming through the belt. Instead, Threepeaters will replace them. Also, Hot Potato begins to be given.
You can now begin digging up the Peashooters to make room for the Threepeaters. Recommended places to place the Threepeaters are in the second, third, fourth rows, so that all of the heads of the Threepeater can fire. Remember to continue to heal your Chard Guards when they are low on health. If the Hunter Zombies or winds freeze your plants, use Hot Potato to thaw them out.
By the time the final wave hits, you should have most of your Peashooters replaced with Threepeaters. Use any remaining Plant Foods wisely, and you should have no problem finishing the level. Congratulations, you win. More chilling levels await you in the Frostbite Caves.