Petunias plants are prolific bloomers which is why they are enduringly popular.
Whether the petals are single or double todays varieties are much more weather resistant than the old strains and will repeat bloom all summer long. They do enjoy a bit of dead heading which will increase the number of flowers produced over a longer period.
Petunias look spectacular planted en masse in beds, borders or containers but they are just as effective planted into baskets and window boxes with other bedding and container plants. Combine them with showy fuchsias, frothy bacopa or lobelia and foliage plants such as trailing nepeta or lysimachia for a truly show stopping display.