Native to South America, the first petunia (Petunia multiflora) specimen was collected by an explorer at the mouth of the Rio de la Plata and was white in color. The original varieties were hardy plants that had trailing 2-3 inch stems and incredible scents. These scents have been lost in many of the modern-day varieties. Fortunately many of the heirloom varieties are still available to gardeners interested in growing petunias. The trailing types are suitable for growing in hanging baskets. Plants grow 10-18 inches tall. Self-seeding annual.
Petunias require full sunlight to thrive, but will tolerate some shade. The more shade they receive, the fewer flowers they’ll produce. Soil should be average to rich and well-drained. Prior to planting work a shovelful or two of organic matter, such as compost or well-aged manure, into the soil. This helps condition the soil, which improves drainage, and will also increase the ability of lighter soils to hold water and nutrients.
How to Plant:
Petunias may be grown from seeds or seedlings. If growing from seeds, sow indoors on the surface of the soil, 8-10 weeks prior to last frost. Pinch off the top inch before planting to encourage good branching and transplant when the danger of frost has past. For good ground cover, space 12-18 inches apart. Fertilize monthly with a balanced organic fertilizer to promote healthy growth and remove spent flowers on a regular basis to extend the blooming period.
Insects and Disease:
Petunias do not have many insect or disease pests. Watch for aphids, flea beetles and slugs, which can occasionally attack plants and use natural pest controls, if necessary. Avoid wetting the foliage when watering to help prevent plant disease.
Seed Saving Instructions:
Petunias are self-seeding. You can save the seed if you’re interested, but the flowers won’t always come true to type. They usually revert to a mix of small white, lavender and rose flowers.