The player can only plant in the first five columns on the first time, because the Flower Pot has not been obtained yet when you play for the first time. When replaying this level, the player can plant the aforementioned plant themselves because he/she has already obtained it.
Bungee Zombies can come down and take the player's plants. On the final wave, they also spawn more zombies.
If the player decides not to buy Roof Cleaners and all the Flower Pots are gone (assuming that they played it for the first time), it is impossible for them to complete the level since the zombies will go down to the chimney and eat their brain, which will result to the loss of the level.
Plant two columns of Sunflowers while planting Potato Mines to kill the first few zombies. Once you have enough sun, start planting Cabbage-pults and Wall-nuts to attack the zombies and shield your plants.
Plant Squashes and Cherry Bombs when zombies get too close to your house.
Replace plants that Bungee Zombies takes, or use instant-kills to kill any Bungee Zombies that drop down. This is not advisable, since it is likely that all the Bungee Zombies will be spread out.
This strategy is similar to the first one but allows you to have more Cabbage-pults. You will need the same plants as the first one. At the beginning of the level, plant a Sunflower. You will get enough time to get 100 sun before any zombies show up. When the first zombie shows up, plant a Cabbage-pult. When you have enough sun, plant the next Cabbage-pult where the next zombie appears. Then collect 100 sun and start the first strategy from planting the Cabbage-pult.
The first part of the dialogue at the start of the level