Where the Sun Don't Shine

Strategy
Usually there are some Squashes, Peashooters, and Smow Peas with the Sunflowers. The zombies that are availible to you are the Normal Zombie, the Buckethead Zombie, and the Football Zombie. You should always place the zombies on the column right next to the red line. If there are no pea shooting plants in a row, put a normal zombie there. If there is a Squash, put two but space them out or else the Squash might kill both zombies. If a row has only Squashes, just use four normal zombies. If the defences are below the minimum defence (see below), use a normal zombie. Anything above, use a buckethead zombie. If you have a row full of snow peas, maybe a footbal zombie is recommended. Usually you shouldn't have to use a football zombie at all.

Obstacles that can kill a normal zombie (minimum defence):

2 Peashooters on the first two colomns left of the red line

1 Snow Pea on the second colomn left to the red line with Sunflower in the front

1 Peashooter on the third colomn left of the red line and nothing on the other two colomns

1 Squash