Introduced to the market in 1995, the Purple Wave petunias took the gardening community by storm with its cascading waves of color that often grow to several feet in length when grown in hanging baskets. Later additions include Pink Wave, Misty Lilac Wave, Rose Wave and Coral Wave. These hardy plants create a blanket of rich color as they tumble over walls, pour out of containers or serve as free flowing ground covers. With similar growing needs to bedding petunias, these prolific plants thrive in summer sun and require attention to both watering and proper fertilization to support their abundant blooms.
Select an area that receives all-day sun. While petunias grow in partial sun, reduced sun inhibits blooming and reduces growth rate.
Prepare the site by tilling the soil to a depth or 8 inches and amending with 2 to 3 inches of well-rotted manure or compost to improve drainage and supply slow-release nutrients to the soil. Container-grown petunias require a lightweight soil mixture. Mix equal parts peat moss, potting soil and either vermiculite or perlite to make your own potting mixture.
Plant wave petunias in the spring after the danger of frost has passed in your area. Although starting them from seed in the home eight to 12 weeks prior to transplant time provides healthy young plants for spring planting, seed is expensive and seedlings require long-term care. Purchasing seedlings in the nursery provides plants ready to transplant to the garden.
Place four to six petunias seedlings in a 12- to 14-inch pot or space 6 to 12 inches apart when planted in the soil. Firm the soil down with your hands and water to thoroughly moisten the soil.
Fertilize with water-soluble fertilizer designed for flowering plants following the recommended application rate on the container. Apply once a week during periods of rapid growth. Wave petunias require adequate nutrients to support their rapid growth.
Keep soil moist. Wave petunias tolerate dry soil, but thrive when provided adequate water. Container-grown petunias typically require frequent watering, often daily, depending on the size of the container and weather conditions. In-ground petunias require deep watering to moisten the soil to a depth of 6 inches or more once a week and more frequently during hot dry spells.