Tips for Growing Surfinia Summer Double Petunias
Suntory Flowers has reinvented double petunias with a new series bred for performance — Surfinia Summer Double. The Summer Doubles are a spinoff of the world-leading Surfinia petunias that created the entire vegetative petunia class nearly 25 years ago.
Advantages growers will find in the Summer Doubles series include earliness, uniformity, heat and weather tolerance and a superb presentation. Compact plants flower profusely and early, presenting excellent coverage in a 4-inch pots and in baskets. The series is uniform across three colors — Pink, Rose and White. While double petunias are typically later than single-flowered, Surfinia Summer Doubles are the earliest to bloom in the double petunia category.
In the garden, Summer Doubles are tolerant of heat and weather. The flowers remain double even at 90°F. While traditional doubles get soggy in rain, the Summer Double flowers are smaller and tightly held to shed rain with ease. As the season progresses, new flowers emerge to bury old ones, reducing the need for deadheading. Gardeners enjoy three seasons of blooms from spring through fall.
For propagators, Surfinia is a dream to root, in three to four weeks on the bench. Pot rooted cuttings into 4-inch to 6-inch pots or hanging baskets. One liner per pot is recommended using a free-draining, open soil. Temperatures at this stage should be between 55 and 60°F.
• 4-inch pots: four to six weeks with one liner and one pinch.
• 6-inch pots: seven to eight weeks with one liner and two pinches.
• 10-inch baskets: 10 to 12 weeks for 10-inch with three liners and two to three
For larger containers and baskets, plant liners in odd numbers — three or five.
Surfinia petunias will require pinching to encourage the right habit and breaks to get a bushy and spreading plant. The first pinch should occur two weeks after potting.
Irrigation and Fertilization
Keep growing media pH between 5.5 and 5.8. Overwatering will lead to root rot. A little-and-often regime is encouraged when plants are young. As they grow, Surfinia petunias become heavy feeders. Using slow-release fertilizer is recommended as they grow in addition to liquid fertilizer.
Controlling Plant Growth
Surfinia petunias respond to plant growth regulators. Apply B9 or other daminozide products at a rate of 2,500 to 5,000 parts per million. A Bonzi drench can be applied at 1 to 3 parts per million. Apply as needed. Surfinia grows rapidly in high light and high heat.
Pests and Diseases
Key pests to monitor are aphids, fungus gnats, mites, shore flies, thrips and whiteflies. Diseases include Botrytis, Phytophthora, Pythium, powdery mildew and Rhizoctonia.