March 2003

Culture Tips for Petunia Double Wave By Carrie Burns

The Double Wave series’ spreading habit makes this petuniagreat for basket production and for mass planting in outdoor beds. Cousin tothe popular Wave series, the Double Wave series shares many of the samecharacteristics. Long-day plants are covered in medium-size flowers thatpossess excellent weather tolerance, but these flowers are fully double.

Double Wave starters are offered as lighted 105-cell trayliners in seven colors: Lavender, Misty Lilac, Pink, Purple, Rose, White and,new for 2003, Blue Vein. They are available in two forms: as a rooted cutting(RC) and a tissue culture liner (TC). Rooted cuttings are the cheaper of thetwo options, but TC liners produce multiple shoots and grow rapidly to fillbaskets and large containers with fewer liners.

Scheduling

Total crop time.Total crop time is 12-16 weeks in the spring and 9-13 weeks in the summer.

Transplant to flower.During the spring, transplant to flower for Double Waves is 5-10 weeks underlong days. With one plant per 6-inch pot, finish time in the spring is 5-7weeks. With four plants RC or two TC per 12-inch basket, finish time is 7-10weeks. During the summer, time is sped up by one week at 4-9 weeks under longdays with high light and a minimum night temperature of 65° F. With one plantper 6-inch pot, finish time in the summer is 4-6 weeks, while a 12-inch basketwith four RC plants or two TC plants finishes in 6-9 weeks in the summer.

Growing On

Double Waves work best in containers four inches or largerwith one plant per 4- to 6-inch pot. Twelve-inch baskets require 3-4 plantsusing the RC form and two using the TC clump liners.

Use a well-drained, disease-free, soilless media with a pHof 5.5-6.3 and an initial nutrient charge. Night temperatures should be55-65° F, day temperatures 65-75° F.

Double Wave petunias are long-day plants, requiring dayslonger than 12 hours to initiate flowering. The plugs will have been lightedduring their rooting stage, but they may require additional supplementallighting after transplanting if the days are less than 12 hours. Double Waveswill sometimes begin flowering with less than 12 hours in high light areas.

Both HID and incandescent lights are equally effective forflower induction; however, plants grown under incandescent lights will stretch moreand need more PGRs to control plant size. Incandescent lights will also affectplant habit by causing shoots to be more upright than they would be under shortdays. Plants will resume their normal spreading habit under natural lightconditions in the garden. Keep light levels as high as possible whilemaintaining moderate temperatures. High light levels or PGR applications maycause pink splashes or stripes to appear on the blooms of ‘Double Wave White’.

Fertilizers and Growth Regulators

Double Waves require more fertilizer than is usuallyrecommended for petunias. Apply a balanced fertilizer with every irrigation ata rate of 200-250 ppm nitrogen. An optional top dressing with slow-releasefertilizer can be applied 10 days before shipping.

For 6-inch pots and hanging baskets, a B-Nine spray at3,000-5,000 ppm 7-10 days after transplanting, followed by another applicationseven days later, is recommended. For 6-inch pots, use a Bonzi drench one timeat 5 ppm, 3-4 weeks after transplanting or when shoots have reached the edge ofthe pot. Follow with a Bonzi spray one time at 30 ppm after visible bud foradditional control. For hanging baskets, use a Bonzi spray one time at 30 ppm,3-4 weeks after transplanting. If necessary, a second Bonzi spray can be applied.

Another option for 6-inch pots is to apply a Bonzi spray at50-60 ppm or a tank mix of 30 ppm Bonzi and 2,500 ppm B-Nine 2-3 weeks aftertransplant, with a possible repeat application 10 days later. For baskets, aBonzi drench at 3-5 ppm may be used as an alternate application. Repeatdrenches are not advised, as they are found to hold plants longer than desired.

The Double Wave Series is available from TwyfordInternational, Apopka, Fla.