Plant of the Month: Trailing Petunias

Original Wave Petunias

Original Wave Petunias

Whether you call them trailing petunias or groundcover petunias, these plants make a major impact for very little money–always a valuable attribute for annuals. The two major U.S. trade styles are Wave™ petunias, developed by Ball Horticultural, and Supertunias®, a Proven Winners® introduction. Also available are the Plush petunias and Ramblin petunias, from Syngenta Flowers, and Suntory’s Surfinia® petunias. All of the petunias are extremely aggressive growers, although the Supertunias are said to be slightly less competitive with other plants, making them perhaps better candidates for mixed container plantings. If you want your trailing petunias to co-exist with other plant material in containers, pair them with equally aggressive annuals:  Potato Vine (Solanum jasminoides), Sweet Potato Vine (Ipomoea batatas), Bacopa, or Proven Winner’s Superbena® verbena. If in doubt, look for the words “vegetative growth” or “spreading” in any descriptive material on the potential container plant partner.

Although Suntory claims that the Surfinia petunias can be grown in full sun or partial shade, assume that any of these petunias will grow best with at least 6 hours of sun per day. Also, petunias are long-day plants–they need long days to flower most abundantly. The Shock Wave petunias and the Syngenta petunias are said to be less day-length sensitive. Other than the Syngenta petunias, all of the trailing petunias are self-cleaning, meaning that deadheading isn’t required.

Waves were bred as groundcover petunias (although they perform well in containers), and they have longer internodes than the Supertunias, so the greater distance between growth points–and flowers–gives them a more open look. Waves also have more slender, flexible internodes than vegetatively propagated petunias, which translates to possibly greater wind resistance. My Wave petunias (shown in the photo) have endured some punishing winds with no stem breakage.

Color selection for Waves, Supertunias and Surfinias include a broad range of pure colors–reds, blues, purple, white, pinks, and even some yellows. Supertunias and Surfinias offer picotees:  Supertunia’s “Pretty Much Picasso” is particularly stunning with its deep pink base color surrounded by a thin, apple-green edging. Easy Wave “Burgundy Star” is a purple and white striped petunia, while Tidal Wave “Silver” is white with a purple throat and veins.

Waves, Supertunias and Surfinias are classically shaped petunia flowers with the exception of Surfinia “Lime” and Surfinia “Yellow”, both of which have lily-shaped flowers. Double petunias are available in all three lines. The Surfinia doubles are especially lovely with their delicate, papery petals resembling bougainvillea bracts.

Supertunias and Surfinias are all vegetatively propagated; Wave, Plush and Ramblin petunias are propagated from seed. Since the Syngenta petunias, Plush and Ramblin, are not self-cleaning, come in limited colors, and rather miserably failed a field test by Cornell University, I’m not going to include any additional information on them here.

Wave Basics

Wave Petunias have been on the market since 1995. They can be grown from seed or propagated from cuttings. There are five varieties of Waves:

Variety                              Height                    Spread                    Bloom Size

  1. Original Wave             5″-7″                      36″-48″                       2″                                                                                 13-18 cm               90-121 cm                   5 cm
  2. Easy Wave                   6″-12″                   30″-36″                       2″                                                                                 15-30 cm               75-99 cm                     5 cm
  3. Tidal Wave                  16″-22″                 30″-60″                       2 1/2″-4″                                                                   40-55 cm               75-152 cm                   6-10 cm
  4. Shock Wave                 7″-10″                   30″-36″                       1 1/2″                                                                          18-25 cm              75-90 cm                     4 cm
  5. Double Wave               6″-8″                     18″-24″                       2″                                                                                 15-20 cm               45-60 cm                     5 cm

The Shock Waves have the smallest flowers and are supposed to bloom earlier and longer than other Waves.

Surfinia Basics

All Surfinias are propagated vegetatively. There are three varieties of Surfinias:

Variety                              Height                    Spread                    Bloom Size

  1. Mounding                    12″                          12″-18″                       1 1/2″                                                                         30 cm                     30-45 cm                    4 cm
  2. Trailing                        5″-7″                      48″                               2″                                                                               13-18 cm              121 cm                        5 cm                                      (Note: “Giant Blue” and “Giant Purple” have 3″/7 cm blooms.)
  3. Summer Doubles        12″-16″                  40″-48″                      1 1/2″                                                                          30-40 cm               102-121 cm               4 cm

Supertunia Basics

Supertunias entered the retail market in 2006. They are propagated vegetatively. There are four varieties of Supertunias:

Variety                              Height                    Spread

  1. Regular                        6″-12″                    8″-24″                                                                                                             15-30 cm              20-60 cm                                                                  (Note:  The spread depends on the particular color selected.)
  2. Minis                            4″-8″                      8″-24″                                                                                                             10-20 cm               20-60 cm                                                                   (Note:  Minis have smaller flowers than the Regular Supertunias. They are claimed to tolerate light shade. Like the Regulars, the spread of the Mini depends on the color selected.)
  3. Doubles                        6″-10″                    8″-12″                                                                                                              15-25 cm               20-30 cm
  4. Vista®                          16″-24″                  18″-24″                                                                                                            40-60 cm               45-60 cm

 I couldn’t find bloom size information on the Supertunias, but online photographs indicate sizes similar to Waves or Surfinias of like height and spread.

Planting and Care

When planted in the ground, add a 6-month slow-release, balanced fertilizer to the soil. Supplemental monthly fertilizer should be a fast-acting variety high in nitrogen and also including iron. Space plants 12″-18″ (30-45 cm) apart. Plants need at least 1″ (3 cm) of water per week–or more if flowers appear to droop.

Trailing petunias planted in containers are most effective in large pots (at least 12″/ 30 cm diameter). Use three plants per 12″/30 cm diameter container. Fill containers with a lightweight potting soil, adding a sprinkling of water-holding crystals and 6-month slow-release, balanced fertilizer every 4″ (10 cm). Supplemental weekly or bi-weekly fertilizer should be a fast-acting variety high in nitrogen and also including iron. Water thoroughly, but sparingly while plants are still young. Once plants start to trail (about 4 weeks after planting), you may need to water daily. When plants achieve full growth, you will almost certainly need to water daily if there is no rain.

Whether planted in the ground or in containers, if plants start to appear leggy, they can be sheared back up to 3″ (7 cm) in mid to late July. Container plants can also be pinched early to promote more compact growth.

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