The plants are the protagonists of Plants vs Zombies, and also your only method of defending your home from the incoming zombie horde. In order to plant these Plants, you need sunlight.This is automatically earned when the sun is shining, but must be gained from other plants during the nighttime. Sunlight is also gained through Plants as some will generate Sunlight over time.
In Plants vs Zombies, the area is divided into day, night, pool area, fog and roof top. Each of these changes affect the gameplay as during nighttime, sunlight will not generate naturally and you must rely on special plants. Depending on the area, specific plants must be used in order to defend yourself effectively