By Heather Kirk-Ballard

LSU AgCenter Horticulturist

Are you looking for reliable, easy-care color for the landscape this summer? Look for new and improved petunias that tolerate the heat. Petunias of the past couldn’t handle the heat, but newer varieties have improved tolerance.

The LSU AgCenter Louisiana Super Plants program has promoted two such improved varieties. First is the Supertunia Vista Bubblegum petunia. This is one of the best-performing petunias in the landscape. In trials at the LSU AgCenter Hammond Research Station, Supertunia Vista Bubblegum was a top performer. The flowers are bright pink and prolific.

Supertunia Vista Mini Indigo is also a Louisiana Super Plant selection. Featuring smaller blooms, Supertunia Vista Mini Indigo adds a splash of deep purple to the landscape. Another great petunia I am particularly fond of is a new release for 2022: the Capella Hello Yellow. This is a true yellow — not a typical color for petunias. Pair it with the indigo and you have a great purple and gold combination.

Supertunias are durable, outstanding annual bedding plants for all of Louisiana. Petunias are one of the most popular annuals in home gardens. A French botanist named Petun discovered these flowers in Argentina in the mid 1800s. This is how the flower got its name. Petun started the flowers from seeds he collected and brought back to Europe, where they became popular.

Supertunias are easy-care plants that need little routine maintenance. They grow best in full to partial sun in well-drained soils. Petunias prefer an acidic soil in the pH range of 5.5 to 6.5.

Plants grow to an average height of 6 to 12 inches and can trail up to 2 to 3 feet. Space plants in the garden 12 to 24 inches apart. Mulch with pine straw, leaves or pine bark to help maintain a clean appearance of the landscape bed, to minimize moisture loss and to help control weeds. Mulches also insulate the soil, keeping roots warm when temperatures drop.

Petunias perform well in both landscape beds and in container plantings. Plants will produce the most flowers if an application of controlled-release fertilizer is incorporated into the soil at the time of planting for both landscape and container plantings.

Petunias in containers will need to be fed more regularly, as nutrients leach from the containers with every watering. You can feed with a liquid fertilizer every 14 days, or you can apply a controlled, slow-release fertilizer about every two months. All varieties of Supertunias are heavy feeders.

Supertunias have a vigorous growth rate with a mounding, trailing habit. Petunias have been used for their beautiful flowers and colors in the landscape to attract pollinators such as butterflies and hummingbirds. Supertunias are continuous bloomers and are self-cleaning, meaning they do not have to be deadheaded to encourage new blooms. Plants are most commonly used as an edging plant or ground cover in the landscape and as filler and spiller in container plantings. They are also excellent selections for hanging baskets.

If your plant begins to look thin, leggy or a bit tired, an allover trim can be beneficial. Use a sharp pair of pruners or scissors to trim back up to one third of the plant. After trimming, it is a good practice to apply a water-soluble fertilizer to provide plants a jump on new growth and to encourage branching and robust flowers.

Petunias look great when mass planted in the landscape bed for a striking display of color. Plants should be spaced with 18-inch centers. Petunias work equally well in containers and hanging baskets where the flowers can cascade over the edges. Always plant the transplants at the original cell pack or pot depth. Both Louisiana Super Plant varieties can commonly be found in 4- or 6-inch pots at garden centers.

The more heat-tolerant petunias — including Supertunia Vista Bubblegum and Supertunia Mini Vista Indigo — can be over-summered successfully.

There are eight series of Supertunias on the market, and they are categorized by their flower and foliage sizes. The Supertunia Charm and Mini Vista series have miniature flowers with a global trailing habit of 2 feet and 4 feet, respectively. The Supertunia Trailing series has medium-sized flowers with a 6-foot trailing habit. Suptertunia, Supertunia Double, Supertunia Picasso and Supertunia Vista all have large flowers and trail up to 4 feet. Supertunia Giant has giant flowers with a vigorous trailing habit of 6 feet.

There are many types of Supertunia hybrids available at garden centers. The newest cultivars offered are Honey, Really Red, Picasso, Latte, Royal Velvet, Bordeaux, White, Limoncello, Raspberry Rush, Lovie Dovie, Trailing Strawberry Pink Veined, Black Cherry, Daybreak Charm, Blue Skies, Trailing Silver, Giant Pink, Trailing Blue Veined, Trailing Rose Veined, Royal Magenta, Bermuda Beach, Mulberry Charm and Trailing Blue. Also look for the Double petunia hybrids, Priscilla and Sharon.

Supertunia Vista Bubblegum is an excellent landscape bedding plant that tolerates the heat. Photo by Heather Kirk-Ballard/LSU AgCenter

Hello Yellow is a new release for 2022 that is a true yellow petunia. Photo by Randy LaBauve/LSU AgCenter

Supertunia Mini Vista Indigo is a Louisiana Super Plant selection. Photo by Craig Gautreaux/LSU AgCenter