Any fertile soil with excellent drainage.
Full sun to partial shade.
Very slight. Established plants in a sheltered location can sometimes survive winter in mild climates.
Mix a standard application of a balanced organic fertilizer into the soil prior to planting along with a generous helping of well-rotted compost. Fertilize established petunias monthly from midsummer to fall.
Pepper, Asparagus, Tomato, Beans, Basil and Corn. The most vigorous petunias like to sprawl, so they make great foreground plants for upright neighbors like sunflowers or zinnias. They also make excellent flowers for mixed containers.
Single Plants: 11″ (30cm) each way (minimum)
Rows: 9″ (25cm) with 1′ 1″ (35cm) row gap (minimum)
Sow and Plant
Many excellent petunia varieties can be grown from seed, or you can start with plants grown from rooted cuttings. Petunia seeds are small but easy to handle. The seedlings need bright light to grow well. Most gardeners buy petunias as inexpensive bedding plants, set out in spring as soon as danger of frost has passed. Large varieties may need wider spacing, or you can grow them in 14-inch (35cm) diameter containers.
Petunias come in many colors and bicolors, and some varieties have frilly double blossoms. The more petals in a petunia blossom, the more likely it is to become heavy with rain and smash to the ground.
Petunias bloom longer and stronger when old blossoms and seed capsules are snipped off every week or so.
Few pests bother petunias, which are members of the nightshade family. Mites, leaf miners and budworms cause occasional problems.