Melon-y Lane

This can be achieved easily in the Survival Levels, especially in Survival: Endless and Survival: Roof, Last Stand and all three-wave daytime levels.

Strategy
Playing Last Stand can let you get this achievement since you have enough sun to plant 6 Winter Melons but you must put 1 in each lane. To speed up the process simply place a lot of Sunflowers and an Imitater Sunflowers.

Trivia

 * You can get this achievement without keeping the Winter Melons alive.
 * You can't get this achivement on the GOTY edition or Ipad edition.