i never got past it to.

this is the hint imaloser

Rooftop is hard I know!
But I beat the game.

You need sunflowers, pots, corn, cabbage, squash, potato bomb, and chile peppers.

Plant sunflower first. When you see the first zombie coming plant a potato bomb in its
path. the plant more sunflowers. repeat this process for a few zombies. once you have a
good economy plant a corn in the path of a zombie. then continue planting corn and cabbage
(don't forget to add your pots)

I usually do 2 rows of sunflowers
row of corn (start planting pots)
row of cabbage (continue planting pots)
another row of corn
then I start digging up a row of sunflowers and planting corn (only do this if you have
enough sun build up to maintain your spot kills AKA pepper, and squash)

Hope that helps

easy